For many, fitness trackers have become indispensable tools for monitoring how many calories they’ve burned in a day. But for those living with obesity, who are known to exhibit differences in walking gait, speed, energy burned and more, these devices often inaccurately measure activity – until now.
Scientists at Northwestern University have developed a new algorithm that enables smartwatches to more accurately monitor the calories burned by people with obesity during various physical activities.
The technology bridges a critical gap in fitness technology, said Nabil Alshurafa, whose Northwestern lab, HABits Lab, created and tested the open-source, dominant-wrist algorithm specifically tuned for people with obesity. It is transparent, rigorously testable and ready for other researchers to build upon. Their next step is to deploy an activity-monitoring app later this year that will be available for both iOS and Android use.
“People with obesity could gain major health insights from activity trackers, but most current devices miss the mark,” said Alshurafa, associate professor of behavioral medicine at Northwestern University Feinberg School of Medicine.
Current activity-monitoring algorithms that fitness trackers use were built for people without obesity. Hip-worn trackers often misread energy burn because of gait changes and device tilt in people with higher body weight, Alshurafa said. And lastly, wrist-worn models promise better comfort, adherence and accuracy across body types, but no one has rigorously tested or calibrated them for this group, he said.
“Without a validated algorithm for wrist devices, we’re still in the dark about exactly how much activity and energy people with obesity really get each day — slowing our ability to tailor interventions and improve health outcomes,” said Alshurafa, whose team tested his lab’s algorithm against 11 state-of-the-art algorithms designed by researchers using research-grade devices and used wearable cameras to catch every moment when wrist sensors missed the mark on calorie burn.
The findings will be published June 19 in Nature Scientific Reports.
The exercise class that motivated the research
Alshurafa was motivated to create the algorithm after attending an exercise class with his mother-in-law who has obesity.
“She worked harder than anyone else, yet when we glanced at the leaderboard, her numbers barely registered,” Alshurafa said. “That moment hit me: fitness shouldn’t feel like a trap for the people who need it most.”
Algorithm rivals gold-standard methods
By using data from commercial fitness trackers, the new model rivals gold-standard methods of measuring energy burn and can estimate how much energy someone with obesity is using every minute, achieving over 95% accuracy in real-world situations. This advancement makes it easier for more people with obesity to track their daily activities and energy use, Alshurafa said.
How the study measured energy burn
In one group, 27 study participants wore a fitness tracker and metabolic cart – a mask that measures the volume of oxygen the wearer inhales and the volume of carbon dioxide the wearer exhales to calculate their energy burn (in kilocalories/kCals) and resting metabolic rate. The study participants went through a set of physical activities to measure their energy burn during each task. The scientists then looked at the fitness tracker results to see how they compared to the metabolic cart results.
In another group, 25 study participants wore a fitness tracker and body camera while just living their lives. The body camera allowed the scientists to visually confirm when the algorithm over- or under-estimated kCals.
At times, Alshurafa said he would challenge study participants to do as many pushups as they could in five minutes.
“Many couldn’t drop to the floor, but each one crushed wall-pushups, their arms shaking with effort,” he said, “We celebrate ‘standard’ workouts as the ultimate test, but those standards leave out so many people. These experiences showed me we must rethink how gyms, trackers and exercise programs measure success – so no one’s hard work goes unseen.”
Health workers have long relied on Body Mass Index as a way to measure whether people are within a healthy weight range. Now, a collection of top researchers have made the case for a new way to understand and diagnose obesity. In part two of this special Spotlight series, we take a look at what this new framing might mean for South Africa.
If we are going to tackle the global rise in obesity, our understanding of the condition needs to change. That is according to a Lancet Commission convened by a global group of 58 experts from different medical specialties. While we have historically thought of obesity as a risk factor for other diseases like diabetes, the commission’s recent report published in the journal Lancet Diabetes and Endocrinology concludes that obesity is sometimes better thought of as a disease itself – one that can directly cause severe health symptoms (see part one of this series for a detailed discussion of this argument).
By categorising obesity as a disease, public health systems and medical aid schemes around the world would be more likely to cover people for weight-loss drugs or weight-loss surgery, according to the report. At present, these services are often only financed if a patient’s obesity has already led to other diseases. This is given that obesity is not viewed as a stand-alone chronic illness.
But if we’re going to redefine obesity as a disease, or at least some forms of it, then we need good clinical definitions and ways to measure it. For a long time, this has posed challenges, according to the Lancet report.
The perils of BMI
At present, health workers often rely on Body Mass Index (BMI) to gauge whether a patient is within a healthy weight range. BMI is measured by taking a person’s weight in kilograms and dividing it by their height in meters squared.
A healthy weight is typically considered to be between 18.5 and 25. A person whose BMI is between 25 and 30 is considered to be overweight, while someone with a BMI of over 30 is considered to have obesity. But according to the Lancet report, this is a crude measure, and one which provides very little information about whether a person is actually ill.
One basic issue is that a person can have a high BMI even if they don’t have a lot of excess fat. Instead, they may simply have a lot of muscle or bone. Indeed, the report notes that some athletes are in the obese BMI range.
Even when a high BMI does indicate that a person has obesity, it still doesn’t tell us where a person’s fat is stored and this is vital medical information. If excess fat is stored in the stomach and chest, then it poses more severe health risks than when it is stored in the limbs or thighs. This is because excess fat will do more harm if it surrounds vital organs.
The lead author of the Lancet report, Professor Frances Rubino, says that the pitfalls of BMI have long been understood, but practitioners have continued to use it.
“BMI is still by and large the most used approach everywhere, even though medical organisations have [raised issues] for quite some time,” he tells Spotlight.
“The problem is that even when we as individuals or organisations say BMI is no good, we haven’t provided an alternative. And so, inevitably, the ease of calculating BMI and the uncertainties about alternatives makes you default back to BMI.”
To deal with this problem, the report advocates for several alternative techniques for measuring obesity which offer more precision.
The first option is to use tools that directly measure body composition like a DEXA scanner. This is a sophisticated x-ray machine which can be used to distinguish between fat, bone and muscle. It can also be used to determine where fat is concentrated. It’s thus a very precise measurement tool, but the machines are expensive and the scans can be time-consuming.
Alternatively, the report recommends using BMI in combination with another measure like waist-to-hip ratio, waist-to-height ratio or simply waist circumference. If two of these alternative measures are used, then BMI can be removed from the picture.
These additional metrics are clinically useful because they provide information about where fat is stored. For instance, a larger waistline inevitably indicates a larger stomach. Indeed, studies have found that above a certain level, a larger waist circumference is linked to a higher chance of dying early, even when looking at people with the same BMI.
The report thus offers a more accurate way to measure obesity in the clinical setting. But its authors argue that this is only the first step when making a diagnosis. The second is to look at whether a patient’s obesity has actually caused health problems as this isn’t automatically the case. They acknowledge for instance that there are some people with obesity who “appear to be able to live a relatively healthy life for many years, or even a lifetime”.
The report refers to these cases as “preclinical obesity”. Such patients don’t have a disease as such, according to the report, but still have an increased risk of facing health issues in the future. As such, the report’s authors argue that they should be monitored and sometimes even treated, depending on factors like family history.
By contrast, cases of obesity which have directly caused health problems are referred to as “clinical obesity”. These cases, according to the report, should be treated immediately just like any other serious disease. It lists a series of medical symptoms associated with clinical obesity that would allow health workers to make an appropriate diagnosis.
The recommendation is thus for health workers to determine whether a person has obesity through the metrics listed above, and then to determine whether it is clinical or preclinical by evaluating a patient’s symptoms. This will inevitably guide the treatment plan.
How does this relate to SA?
Professor Francois Venter, who runs the Ezintsha research centre at WITS university, says the Lancet report offers a good starting point for South Africa, but it has to be adapted for our own needs and context.
“It’s a big step forward from BMI which grossly underdiagnoses and overdiagnoses obesity,” says Venter, who adds that additional metrics like waist circumference are a “welcome addition”.
The view that clinical obesity is a disease that needs to be immediately treated is also correct, according to Venter. Though he adds that the public health system in South Africa is not in a financial position to start handing out weight-loss medicine to everyone who needs it.
“The drugs are hugely expensive,” says Venter, “and they have side effects, so you need a lot of resources to support people taking them.” But while it may not yet be feasible to treat all cases of clinical obesity in South Africa, Venter believes we should use the diagnostic model offered by the Lancet Commission to begin identifying at least some people with clinical obesity so that they can begin treatment.
“You have to start somewhere, and for that you need a good staging system,” he says. “Let’s use the Lancet Commission and start to see if we can identify a few priority people and screen them and start to work on the drug delivery system.”
Yet while Venter believes that the commission makes important contributions, he also cautions that we need more data on obesity in Africa before we can apply all of its conclusions to our own context.
“If you go to the supplement of the Lancet Commission, there’s not a single African study there. It all comes from Europe, North America and Asia. It’s not the commission’s fault but [there is a lack of data on Africa].”
This is important as findings that apply to European or Asian populations may not necessarily hold for others. Consider the following case.
As noted, the commission states that BMI is not sufficient to determine whether someone is overweight and must therefore be complemented with other measures. But it states that if someone’s BMI is above 40 (way above the current threshold for obesity), then this can “pragmatically be assumed” without the need for further measures.
But this may not hold in Africa, says Venter.
“The commission says that if your BMI is over 40, which is very big, you can infer that this person has got obesity and they are sick and need to lose weight. I don’t know if we can say that in Africa, where we often have patients who are huge, and yet they are very active, and when you [look at] their blood pressure and all their metabolics, they’re actually pretty healthy,” he notes. “So, I think they’re sometimes jumping to conclusions about African populations that we don’t have data on,” adds Venter.
Is South Africa ready to move past BMI?
Another concern is that while the Lancet Commission may offer useful recommendations for advanced economies, its starting assumptions may not be as relevant for countries like South Africa.
For instance, while specialists agree that BMI is a crude measure of obesity, direct measures like DEXA scans are “out of our reach economically”, according to Professor Susan Goldstein, who leads PRICELESS-SA, a health economics unit at the South African Medical Research Council.
And while supplementing BMI with the other metrics like waist circumference may be doable, health experts told Spotlight that at present healthcare workers in South Africa aren’t even measuring BMI alone.
Dr Yogan Pillay, a former deputy director-general at the national health department who now runs TB and HIV delivery at the Gates Foundation, told Spotlight: “I can’t tell you how few people in the public sector have their BMI monitored at all. Community health workers are supposed to be going out and measuring BMI, but even that’s not happening”.
Goldstein also suggests that the monitoring of BMI in South Africa is limited. “If you go into the clinic for your blood pressure, do they say: ‘How’s your BMI?’ No, I doubt that,” says Goldstein. “It’s just not one of the measures that [gets done].”
She adds that South Africa could introduce the combination of metrics proposed by the commission, like waist circumference combined with BMI, but says it would simply require “a lot of re-education of health workers”.
Prevention vs treatment
For Goldstein, the commission is correct to regard clinical obesity as a disease which needs to be treated, but we also shouldn’t view medication as the only way forward.
“We have to remember that prevention is very important,” says Goldstein. “We have to focus on food control, we have to look at ultra-processed foods, and unless we do that as well [in addition to medication] we are going to lose this battle.”
The National Health Department already has a strategy document for preventing obesity, but some of its recommendations have been critiqued for focusing on the wrong problems. For instance, to prevent childhood obesity, the strategy document recommends reforming the Life Orientation curriculum and educating tuck shop vendors so that both students and food sellers have more information about healthy eating. But as Spotlight previously reported, there are no recommendations to subsidise healthy foods or to increase their availability in poor areas, which several experts believe is more important than educational initiatives.
Venter also highlights the importance of obesity prevention, though he emphasises that this shouldn’t be in conflict with a treatment approach – instead, we need to push for both.
“The [prevention] we need to do is fix the food supply… and the only way you do that is to decrease the cost of unprocessed food.” But while this may help prevent future cases of obesity, it doesn’t help people who are already suffering from obesity, says Venter. And since such people comprise such a large share of the population, we can’t simply ignore them, he says.
“Even if you fix the entire food industry tomorrow, those [people who are already obese] are going to remain where they are because simply changing your diet isn’t going to do diddly squat [when you already have obesity],” he adds. (Part 1 discusses this in more detail).
Goldstein adds that increasing access to treatment would also inevitably reduce the costs of “hypertension, diabetes, osteoarthritis, and a whole range of other illnesses if it’s properly managed”.
One way to advance access to medication would be for the government to negotiate reduced prices of GLP-1 drugs, she says. (Spotlight previously reported on the prices and availability of these medicines in South Africa here.)
Funding
A final concern that has been raised about the Lancet commission is about its source of funding.
“I don’t know how one gets around this,” says Goldstein, “but there were 58 experts on the commission, 47 declared conflicts of interest.”
Indeed, the section of the commission that lists conflicts of interest spans over 2 000 words (roughly the size of this article). This includes research grants and consulting fees from companies like Novo Nordisk and Eli Lilly, which produce anti-obesity drugs.
In response, Rubino told Spotlight that “people who work in the medical profession obviously work and consult, and the more expertise they have, the more likely they are to be asked by somebody to advise. So sometimes people have contracts to consult a company – but that doesn’t mean that they necessarily make revenue if the company has better sales. You get paid fees for your services as a consultant”.
Rubino says this still has to be declared as it may result in some bias, even if it is unconscious, but “if you wanted to have experts who had zero relationship [to companies] of any sort then you might have to wonder if there is expertise available there… the nature of any medical professional is that the more expertise they have, the more likely that they have engaged in work with multiple stakeholders”.
For Venter, there is some truth to this. “It’s very difficult to find people in the obesity field that aren’t sponsored by a drug company,” he says. “Governments don’t fund research… and everyone else doesn’t fund research. Researchers go where the research is funded.”
This doesn’t actually solve the problem, says Venter, as financing from drug companies can always influence the conclusions of researchers. It simply suggests that the problem is bigger than the commission. Ultimately, he argues that the authors should at least be applauded for providing such granular details about conflicts of interest.
Rubino adds that while researchers on the commission may have historically received money from drug companies for separate research studies or consulting activities, none of them received money for their work on the commission itself.
“This commission has been working for more than four years since conception… An estimate of how many meetings we had is north of 700, and none of us have received a single penny [for doing this],” he says.
Disclosure: The Gates Foundation is mentioned in this article. Spotlight receives funding from the Gates Foundation but is editorially independent – an independence that the editors guard jealously. Spotlight is a member of the South African Press Council.
Eating a high-fat diet containing a large amount of oleic acid – a type of fatty acid commonly found in olive oil – could drive obesity more than other types of dietary fats, according to a study published in the journal Cell Reports.
The study found that oleic acid, a monounsaturated fat associated with obesity but also tentatively linked to cardiovascular benefits and often touted as a ‘healthy’ fatty acid, causes the body to make more lipid cells. By boosting a signalling protein called AKT2 and reducing the activity of a regulating protein called LXR, high levels of oleic acid resulted in faster growth of the precursor cells that form new lipid cells.
“We know that the types of fat that people eat have changed during the obesity epidemic. We wanted to know whether simply overeating a diet rich in fat causes obesity, or whether the composition of these fatty acids that make up the oils in the diet is important. Do specific fat molecules trigger responses in the cells?” said Michael Rudolph, PhD, assistant professor of biochemistry and physiology at the University of Oklahoma College of Medicine.
Rudolph and his team fed mice a variety of specialised diets enriched in specific individual fatty acids, including those found in coconut oil, peanut oil, milk, lard and soybean oil. Oleic acid was the only one that caused the precursor cells that give rise to fat cells to proliferate more than other fatty acids.
“You can think of the fat cells as an army,” Rudolph said. “When you give oleic acid, it initially increases the number of ‘fat cell soldiers’ in the army, which creates a larger capacity to store excess dietary nutrients. Over time, if the excess nutrients overtake the number of fat cells, obesity can occur, which can then lead to cardiovascular disease or diabetes if not controlled.”
Unfortunately, it’s not quite so easy to isolate different fatty acids in a human diet. People generally consume a complex mixture if they have cream in their coffee, a salad for lunch and meat and pasta for dinner. However, Rudolph said, there are increasing levels of oleic acid in the food supply, particularly when access to food variety is limited and fast food is an affordable option.
“I think the take-home message is moderation and to consume fats from a variety of different sources,” he said. “Relatively balanced levels of oleic acid seem to be beneficial, but higher and prolonged levels may be detrimental. If someone is at risk for heart disease, high levels of oleic acid may not be a good idea.”
Authors of a recent Lancet report argue that obesity should not just be seen as a risk factor for other diseases – but in some cases, should be seen as a disease itself. The position could change how we treat obesity globally. In the first of this two-part Spotlight series, we break down the debate around the issue, and its implications for health policy.
In 1990, just 2% of all young people around the world aged 5 to 24 were living with obesity. By 2021, this figure had more than tripled to over 6%. This is according to a recent study, which relied on Body Mass Index (BMI) data from 180 countries and territories around the world. It estimates that the rise in obesity among children and young people will only continue in the coming decades.
South Africa certainly isn’t immune to the crisis. A survey conducted in 2021/2022 found that 16% of all children aged 6 to 18 were “severely overweight”. Meanwhile, World Health Organization (WHO) data suggests that about 30% of all adults in South Africa are living with obesity, meaning a BMI of over 30, which is almost double the global level.
BMI, which simply looks at a person’s weight in relation to their height, is a crude measure of obesity. For instance, a person may have a high BMI simply because they have a lot of muscle rather than fat. But while it is agreed that BMI is a flawed indicator at the individual level, many experts recommend using it as a rough proxy for “health risk at a population level”.
For instance, a study which collected data on nearly three million people found that those who had very high BMI levels were, on average, more likely to die at an early age. The study also found that this was true of people with very low BMI levels (those who were underweight). In this context, the above figures paint a concerning picture.
Given the rising rates, experts argue that we need health systems to be able to track and respond to obesity urgently. But, according to a Lancet Commission published in January, health systems around the world may struggle to do this, because of a failure to accurately conceptualise and measure what obesity actually is.
The Lancet commission was developed by 58 experts from different medical specialties and though it has been the subject of debate, it has since been widely endorsed as a new way to understand obesity. Spotlight takes a look at what it concluded.
Delaying treatment for no reason
Obesity is often regarded as a risk factor for other diseases, for instance, type 2 diabetes. But according to the commission, there are certain cases in which obesity is not just a risk factor, but a disease itself – one that should be immediately treated.
One of the reasons for this is that obesity not only contributes to the emergence of other conditions but sometimes leads to clinical symptoms directly. For example, the cartilage that protects the joints in a person’s knees can sometimes become eroded when adults carry too much weight. In this case, a person could suffer from joint pain, stiffness and reduced mobility where obesity is clearly the cause.
Take another example. If fat deposits build up in the abdomen, this may limit how much the lungs can expand, causing breathlessness. Similarly, a build-up of fat around the neck can narrow a person’s upper airways, which can cause sleep apnoea.
Thus, obesity is not simply something which increases the risk of developing a separate disease in the future – but something which can directly (and presently) affect the functioning of organs.
More broadly, the commission argues that by hindering a person’s “mobility, balance and range of motion” obesity can in certain cases “restrict routine activities of daily living”. In these instances, obesity is a disease by definition, according to the commission. This is given that it defines disease as a “harmful deviation from the normal structural or functional state of an organism, associated with specific signs and symptoms and limitations of daily activities”.
But why does this conceptual debate matter?
Because at present, people often have to wait for other diseases to crop up before insurers or public health systems cover them for weight loss drugs or bariatric surgery – a procedure to help with weight loss and improve obesity-related health conditions. And when they do cover these services, it is often only after severe delay. Because obesity is only considered to be a risk factor, it isn’t typically treated with the same urgency as life-threatening diseases, according to the authors of the commission.
Professor Frances Rubino, the lead author of the commission, details how this problem manifests in the healthcare system.
“I’ve been doing bariatric surgery for 25 years in four different countries; in America, Italy, France and the UK,” he tells Spotlight, “In all of those countries, to meet the criteria for surgery people very often have to undergo six to 12 months of weight monitoring before their surgery is covered. So systematically you delay treatment”.
He continues: “Someone who has clinical obesity and has heart failure as a result of it is waiting for a year for what reason? That condition will only worsen and if the patient is still alive, the treatment [is] going to cost the same amount to the payer but it’s going to be less effective.”
Can’t people just diet?
One of the reasons that some academics have historically been reluctant to classify obesity as a disease is because of a fear that this may reduce people’s agency – instead of taking proactive steps to diet and exercise, people with obesity may simply view themselves as afflicted by a disease.
The belief that people with obesity can simply diet their way out of their situation is in fact partially why Rubino’s patients were forced to wait long periods of time before receiving bariatric surgery.
Rubino explains: “In America, many private payers [i.e. medical insurance schemes] have required weight monitoring programmes, where patients do nothing else other than see a dietician for 12 months, and if they skip one appointment, they have to start all over again. I think that in some cases, this has been misguided by the idea that you want to see if obesity can be reversed by somebody going on a diet.”
This, according to him, is a “misconception”, arguing that if someone faces such severe levels of obesity that they require surgery, diet is unlikely to offer a solution.
Indeed, research has shown that it’s very rare for people with obesity to lose large amounts of weight quickly without surgery or medication. For instance, a study on over 176 000 patients in the UK found that among men with “simply obesity” or a BMI of 30-34.9, only 1 in 210 were able to achieve a “normal” weight level within a year. Among men with morbid obesity or BMI of 35 or more, the chance was less than 1 than in 1000. Chances for women were roughly twice as good as men’s – so still exceedingly small.
Thus, if someone is severely obese and their excess weight is causing life-threatening symptoms, putting them on a diet for a year is unlikely to result in the urgent changes that may be required for them to get better. In fact, Rubino argues that they may simply die of their condition in the interim.
Taking a medical approach more quickly is easier now than ever before due to the regulatory approval of GLP-1 agonists like semaglutide and tirzepatide – Spotlight previously reported on the availability of these new diabetes and weight loss medicines in South Africa. An article by WHO officials from December states that because of the approval of these medicines “[h]ealth systems across the globe now may be able to offer a treatment response integrated with lifestyle changes that opens the possibility of an end to the obesity pandemic”.
Not all people with obesity are ill
There is a more scientific argument against categorising obesity as a disease. This is that while obesity can sometimes result in the negative health symptoms discussed above (like respiratory issues or reduced mobility) it doesn’t always do this.
In fact, the commission acknowledges that some people with obesity “appear to be able to live a relatively healthy life for many years, or even a lifetime”. One of the reasons for this is that excess fat may be stored in areas that don’t surround vital organs. For instance, if fat is stored in the limbs, hips, or buttocks, then this may cause less harm than if it is stored in the stomach.
Since obesity doesn’t always cause health problems, it isn’t always a disease. In order to deal with this conceptual hurdle, the commission classifies obesity into two categories – clinical and preclinical obesity.
If a person has pre-clinical obesity, this means they have a lot of excess fat, but no obvious health problems that have emerged as a result. In this case, obesity is not classified as a disease, though it may still increase the chance of future health problems (depending on a range of factors, like family history).
For a person to have clinical obesity, they must have a lot of excess fat as well as health problems that have already been directly caused by this. It is this that the commission defines as a disease.
This classification system, according to Rubino, ensures not only that we urgently treat people living with clinical obesity, but also that we don’t overtreat people – since if a person falls into the pre-clinically obese group, then they may not need treatment.
But if we’re going to treat clinical obesity as a disease, we’ll need clear methods of diagnosing people. Since BMI is deeply flawed and provides little information about whether a person is ill at the individual level, health systems will need something else. In part 2 of this Spotlight special series, we’ll discuss the options offered by the commission, and how this all relates to the situation in South Africa.
New research from the University of Sydney reveals that obesity, having a knee injury and occupational risks such as shift work and lifting heavy loads are primary causes of knee osteoarthritis.
The study also found that following a mediterranean diet, drinking green tea and eating dark bread could reduce the risk of developing knee osteoarthritis.
Using data from 131 studies conducted between 1988 to 2024, the researchers examined over 150 risk factors in participants ranging from 20 to 80 years old to determine which were associated with an increased risk of developing knee osteoarthritis.
“Our research found that while factors such as eating ultra-processed foods and being overweight increase the risk, addressing lifestyle factors – such as losing weight or adopting a better diet – could significantly improve people’s health,” Associate Professor Abdel Shaheed said.
Co-author Professor David Hunter, a researcher at the Kolling Institute and Professor of Medicine at the University of Sydney, said: “Women were twice as likely to develop the condition than men, and older age was only mildly associated with increased risk.”
Reducing the risk of knee osteoarthritis
Dr Duong, lead author and post-doctoral researcher at the Kolling Institute, said: “Eliminating obesity and knee injuries combined could potentially reduce the risk of developing knee osteoarthritis by 14 percent across the population.
“We urge governments and the healthcare sector to take this seriously and to implement policy reforms that address occupational risks, subsidise knee injury prevention programs, and promote healthy eating and physical activity to reduce obesity.”
Study links higher body mass index at various ages across adulthood with greater risks of developing different types of kidney cancer.
Photo by I Yunmai on Unsplash
Excess weight in mid-life is a known risk factor for kidney cancer, but new research indicates that weight patterns throughout life may also affect an individual’s likelihood of developing this malignancy. The findings are published by Wiley online in CANCER, a peer-reviewed journal of the American Cancer Society.
To assess weight patterns and their associations with kidney cancer and its different subtypes, investigators analysed data from 204 364 individuals from the NIH-AARP Diet and Health Study, including body mass index (BMI) data when participants entered the study (an average age of 61.6 years), and prior BMI recordings at 18, 35, and 50 years of age. The team noted that there were 1,425 cases of kidney cancer, or renal cell carcinoma (RCC), among the study’s participants, with 583 having aggressive RCC and 339 having fatal RCC. The researchers also recorded the different subtypes of RCC, including clear cell RCC (541 patients), papillary RCC (146 patients), and chromophobe RCC (64 patients).
Higher BMI at any of the ages assessed was linked with higher risks of overall RCC and all subtypes (except chromophobe RCC), with a 10-40% higher risk for each 5-unit increase in BMI. Similar increased risks were linked to weight gain during adulthood that resulted in overweight or obesity, compared with maintaining normal BMI.
Also, long-term excess weight was associated with higher risks of overall RCC, aggressive RCC, fatal RCC, and clear cell RCC, but not papillary RCC and chromophobe RCC. Weight loss in which BMI was reduced by at least 10%, particularly later in life, was associated with a lower risk of RCC. Specifically, weight loss from age 18–35 years and after age 50 years was associated with 21% and 28% reductions in RCC incidence, respectively.
“These findings emphasise that maintaining a healthy weight across one’s lifetime is important for reducing RCC risk. More importantly, weight loss, even later in life, may offer protective benefits,” said lead author Zhengyi Deng, PhD, of Stanford University School of Medicine. “We should support initiatives that promote healthy weight maintenance and weight loss strategies. Some of these include lifestyle interventions, weight-loss programs, and emerging medical treatments for obesity; however, individuals should consult with their healthcare providers prior to initiation of any plan.”
Although obese individuals are at greater risk of diabetes, high blood pressure or high cholesterol, not all obese people develop metabolic diseases of this kind. With around a quarter of all obese individuals are healthy, scientists are trying to work out why some obese people become unhealthy while others do not.
Now, a comprehensive study by researchers from Zurich and Leipzig has provided a vital basis for this work. Specifically, the researchers have produced a detailed atlas with data from healthy and unhealthy overweight people, on their fat (adipose) tissue, and on the gene activity in this tissue’s cells. “Our results can be used to look for cellular markers that provide information on the risk of developing metabolic diseases,” explains Adhideb Ghosh, a researcher in ETH Professor Christian Wolfrum’s group and one of the two lead authors of the study. “The data is also of great interest for basic research. It could help us develop new therapies for metabolic diseases.”
For this study, Ghosh and his colleagues used the Leipzig Obesity Biobank, an extensive collection of biopsies taken from obese individuals. Compiled by scientists from the University of Leipzig, these samples originate from obese patients who underwent elective surgery and consented to the collection of adipose tissue samples for research purposes. The collection also includes extensive medical information on the patients’ health.
Since the tissue samples were all taken from obese individuals with or without metabolic diseases, they allow comparison between individuals with healthy and unhealthy obesity. In samples from 70 volunteers, the researchers at ETH Zurich examined which genes were active, and to what extent, on a cell-by-cell basis for two types of adipose tissue: subcutaneous and visceral.
Scientists and medical experts assume that visceral fat, which lies deep in the abdominal cavity and surrounds the internal organs, is primarily responsible for metabolic diseases. By contrast, experts generally believe that fat located directly beneath the skin is less problematic.
For the study, it was vital that the adipose tissue cells were not all simply lumped together, as this tissue comprises not only fat cells (adipocytes) but also cells of other types. “In fact, the adipocytes are in the minority,” explains lead author Isabel Reinisch, a postdoc in Wolfrum’s group. A large part of adipose tissue is made up of immune cells, cells that form blood vessels, and immature precursor cells of adipocytes. Another cell type, known as mesothelial cells, are found only in visceral adipose tissue and mark its outer boundary.
Abdominal fat remodelled – and gender differences
As the researchers were able to show, there are significant functional changes in cells in the visceral adipose tissue of people with metabolic diseases. This remodelling affects almost every cell type in this form of tissue. For example, the genetic analyses showed that the adipocytes of unhealthy individuals could no longer burn fats as effectively and instead produced greater quantities of immunologic messenger molecules. “These substances trigger an immune response in the visceral fat of obese people,” explains Reinisch. “It’s conceivable that this response promotes the development of metabolic diseases.”
The researchers also found very clear differences in the number and function of mesothelial cells: in healthy obese individuals, there is a far greater proportion of mesothelial cells in the visceral fat and these cells exhibit greater functional flexibility. Specifically, the cells can switch into a sort of stem cell mode and therefore convert into different cell types, such as adipocytes, in healthy individuals. “The ability of fully differentiated cells to convert into stem cells is otherwise primarily associated with cancer,” says Reinisch. She was surprised, therefore, to find this ability in adipose tissue as well. “We suspect that the flexible cells at the edge of the adipose tissue in healthy obese individuals facilitate smooth tissue expansion.”
Finally, the researchers also found differences between men and women: a certain type of progenitor cell is present only in the visceral fat of women. “This could explain differences in the development of metabolic diseases between men and women,” says Reinisch.
Finding new biomarkers
The new atlas of gene activity in overweight people describes the composition of cell types in adipose tissue and their function. “However, we cannot say whether the differences are the reason why someone is metabolically healthy or whether, conversely, metabolic diseases cause these differences,” says Ghosh. Instead, the scientists view their work as providing the basis for further research. They have published all the data in a publicly accessible web app so that it is available for other researchers to work with.
In particular, this atlas now makes it possible to find new markers that provide information on the risk of developing a metabolic disease. At present, the ETH researchers are also looking for these kinds of markers, which could help to improve the treatment of such diseases. For example, there is a new class of drugs that suppress the appetite and promote insulin release in the pancreas – but these medications are in short supply. “Biomarkers that can be derived from our data could help to identify those patients who are most in need of this treatment,” says Reinisch.
Calorie content drives food preference despite similar taste in individuals with and without obesity
Source: Pixabay CC0
Higher calorie foods were preferred among individuals with and without obesity despite similar taste and texture, according to a study published December 17th in the open-access journal PLOS Biologyby Albino Oliveira-Maia from the Champalimaud Foundation, Portugal, and colleagues.
Eating sends signals to the brain with information about a food’s energy content, which can influence food preferences irrespective of flavor. People with obesity often have impairments in areas of the brain where dopamine is released, which may drive reward-related eating and a preference for energy-dense foods rich in fat and sugars. Weight loss due to bariatric surgery has been associated to a normalization of reward-related eating with a shift of preferences toward healthier options, but the underlying mechanisms are not well understood.
In this study, after examining a large group of healthy volunteers, researchers compared food preferences in three groups: 11 individuals with obesity, 23 post-bariatric surgery patients, and 27 non-obese control subjects. They gave participants sweetened low-fat yogurt with and without maltodextrin (a carbohydrate that adds calories to the yogurt with no impact on taste or texture). Participants ate the yogurt at home, alternating between the maltodextrin-containing and -free yogurt. All three groups ate more of the maltodextrin-containing yogurt, despite rating both as equally pleasant. Somewhat unexpectedly, the effects of maltodextrin on yogurt consumption were similar in individuals with obesity relative to their non-obese counterparts.
The study also used radioactive iodine labelling and single photon emission computed tomography to visualise dopamine receptors in the brain. Consistent with previous studies, individuals with obesity had lower dopamine receptor availability than non-obese controls. Dopamine receptor availability was similar in the surgical and non-obese groups and was associated with more restrained eating. These results suggest that obesity-related brain changes can be reversed after bariatric surgery, potentially impacting the amount of food consumed but not necessarily the types of food preferred.
The authors add, “We were very intrigued that, while behaviour was guided towards eating yoghurts with higher energy-content, this did not seem to be a result of explicit choices, since consistent changes in pleasantness of flavours enriched with carbohydrates were not found. Importantly, this behaviour was maintained in patients with obesity and after weight-loss surgery, even though there were important differences in their brain dopaminergic system.”
AI image made with Gencraft using Quicknews’ prompts.
Quicknews takes a look at some of the big events and concerns that defined healthcare 2024, and looks into its crystal ball identify to new trends and emerging opportunities from various news and opinion pieces. There’s a lot going on right now: the battle to make universal healthcare a reality for South Africans, growing noncommunicable diseases and new technologies and treatments – plus some hope in the fight against HIV and certain other diseases.
1. The uncertainty over NHI will continue
For South Africa, the biggest event in healthcare was the signing into law of the National Health Insurance (NHI) by President Ramaphosa in May 2024, right before the elections. This occurred in the face of stiff opposition from many healthcare associations. It has since been bogged down in legal battles, with a section governing the Certificate of Need to practice recently struck down by the High Court as it infringed on at least six constitutional rights.
Much uncertainty around the NHI has been expressed by various organisation such as the Health Funders Association (HFA). Potential pitfalls and also benefits and opportunities have been highlighted. But the biggest obstacle of all is the sheer cost of the project, estimated at some R1.3 trillion. This would need massive tax increases to fund it – an unworkable solution which would see an extra R37 000 in payroll tax. Modest economic growth of around 1.5% is expected for South Africa in 2025, but is nowhere near creating enough surplus wealth to match the national healthcare of a country like Japan. And yet, amidst all the uncertainty, the healthcare sector is expected to do well in 2025.
Whether the Government of National Unity (GNU) will be able to hammer out a workable path forward for NHI remains an open question, with various parties at loggerheads over its implementation. Public–private partnerships are preferred by the DA and groups such as Solidarity, but whether the fragile GNU will last long enough for a compromise remains anybody’s guess.
It is reported that latest NHI proposal from the ANC includes forcing medical aid schemes to lower their prices by competing with government – although Health Minister Aaron Motsoaledi has dismissed these reports. In any case, medical aid schemes are already increasing their rates as healthcare costs continue to rise in what is an inexorable global trend – fuelled in large part by ageing populations and increases in noncommunicable diseases.
Further on the horizon, there are a host of experimental drugs undergoing testing for obesity treatment, according to a review published in Nature. While GLP-1 remains a target for many new drugs, others focus on gut hormones involved in appetite: GIP-1, glucagon, PYY and amylin. There are 5 new drugs in Phase 3 trials, expected variously to finish between 2025 and 2027, 10 drugs in Phase 2 clinical trials and 18 in Phase 1. Some are also finding applications beside obesity. The GLP-1 agonist survodutide, for example have received FDA approval not for obesity but for liver fibrosis.
With steadily increasing rates of overweight/obesity and disorders associated with them, this will continue to be a prominent research area. In the US, where the health costs of poor diet match what consumers spend on groceries, ‘food as medicine’ has become a major buzzword as companies strive to deliver healthy nutritional solutions. Retailers are providing much of the push, and South Africa is no exception. Medical aid scheme benefits are giving way to initiatives such as Pick n Pay’s Live Well Club, which simply offers triple Smart Shopper points to members who sign up.
Another promising approach to the obesity fight is precision medicine, which factors in many data about the patient to identify the best interventions. This could include detailed study of energy balance regulation, helping to select the right antiobesity medication based on actionable behavioural and phsyiologic traits. Genotyping, multi-omics, and big data analysis are growing fields that might also uncover additional signatures or phenotypes better responsive to certain interventions.
3. AI tools become the norm
Wearable health monitoring technology has gone from the lab to commonly available consumer products. Continued innovation in this field will lead to cheaper, more accurate devices with greater functionality. Smart rings, microneedle patches and even health monitoring using Bluetooth earphones such as Apple’s Airpods show how these devices are becoming smaller and more discrete. But health insurance schemes remain unconvinced as to their benefits.
After making a huge splash in 2024 as it rapidly evolved, AI technology is now maturing and entering a consolidation phase. Already, its use has become commonplace in many areas: the image at the top of the article is AI-generated, although it took a few attempts with the doctors exhibiting polydactyly and AI choosing to write “20215” instead of “2025”. An emerging area is to use AI in patient phenotyping (classifying patients based on biological, behavioural, or genetic attributes) and digital twins (virtual simulations of individual patients), enabling precision medicine. Digital twins for example, can serve as a “placebo” in a trial of a new treatment, as is being investigated in ALS research.
Rather than replacing human doctors, it is likely that AI’s key application is reducing lowering workforce costs, a major component of healthcare costs. Chatbots, for example, could engage with patients and help them navigate the healthcare system. Other AI application include tools to speed up and improve diagnosis, eg in radiology, and aiding communication within the healthcare system by helping come up with and structure notes.
4. Emerging solutions to labour shortages
Given the long lead times to recruit and train healthcare workers, 2025 will not likely see any change to the massive shortages of all positions from nurses to specialists.
At the same time, public healthcare has seen freezes on hiring resulting in the paradoxical situation of unemployed junior doctors in a country desperately in need of more doctors – 800 at the start of 2024 were without posts. The DA has tabled a Bill to amend the Health Professions Act at would allow private healthcare to recruit interns and those doing community service. Critics have pointed out that it would exacerbate the existing public–private healthcare gap.
But there are some welcome developments: thanks to a five-year plan from the Department of Health, family physicians in SA are finally going to get their chance to shine and address many problems in healthcare delivery. These ‘super generalists’ are equipped with a four-year specialisation and are set to take up roles as clinical managers, leading multi-disciplinary district hospital teams.
Less obvious is where the country will be able to secure enough nurses to meet its needs. The main challenge is that nurses, especially specialist nurses, are ageing – and it’s not clear where their replacements are coming from. In the next 15 years, some 48% of the country’s nurses are set to retire. Coupled with that is the general consensus that the new nursing training curriculum is a flop: the old one, from 1987 to 2020, produced nurses with well-rounded skills, says Simon Hlungwani, president of the Democratic Nursing Organisation of South Africa (Denosa). There’s also a skills bottleneck: institutions like Baragwanath used to cater for 300 students at a time, now they are only approved to handle 80. The drive for recruitment will also have to be accompanied by some serious educational reform to get back on track.
5. Progress against many diseases
Sub-Saharan Africa continues to drive declines in new HIV infections. Lifetime odds of getting HIV have fallen by 60% since the 1995 peak. It also saw the largest decrease in population without a suppressed level of HIV (PUV), from 19.7 million people in 2003 to 11.3 million people in 2021. While there is a slowing in the increase of population living with HIV, it is predicted to peak by 2039 at 44.4 million people globally. But the UNAIDS HIV targets for 2030 are unlikely to be met.
As human papillomavirus (HPV) vaccination programmes continue, cervical cancer deaths in young women are plummeting, a trend which is certain to continue.
A ‘new’ respiratory virus currently circulating in China will fortunately not be the next COVID. Unlike SARS-CoV-2, human metapneumovirus (HMPV) has been around for decades, and only causes a few days of mild illness, with bed rest and fluids as the primary treatment. The virus has limited pandemic potential, according to experts.
A recent population-based study indicates that among children with cancer, those with obesity at the time of diagnosis may face an elevated risk of dying. The findings are published by Wiley online in CANCER, a peer-reviewed journal of the American Cancer Society.
The retrospective study was based on information from the Cancer in Young People in Canada (CYP-C) database, including all children with newly diagnosed cancer aged 2 to 18 years across Canada from 2001 to 2020. Obesity was defined as age and sex-adjusted body mass index at or above the 95th percentile.
Among 11 291 children with cancer, 10.5% were obese at the time of diagnosis. Investigators assessed 5-year event-free survival (survival free of cancer relapse), as well as overall survival.
Compared with patients without obesity at the time of initial cancer diagnosis, those with obesity had lower rates of 5-year event-free survival (77.5% versus 79.6%) and overall survival (83.0% versus 85.9%).
After adjusting for factors including age, sex, ethnicity, neighbourhood income quintile, treatment era, and cancer categories, obesity at diagnosis was linked with a 16% increase in the risk of relapse and a 29% increase in the risk of death. The negative impact of obesity on prognosis was especially pronounced in patients with acute lymphoblastic leukaemia and brain tumours.
“Our study highlights the negative impact of obesity among all types of childhood cancers. It provides the rationale to evaluate different strategies to mitigate the adverse risk of obesity on cancer outcomes in future trials,” said co–senior author Thai Hoa Tran, MD, of the Centre Hospitalier Universitaire Sainte-Justine, in Montreal. “It also reinforces the urgent need to reduce the epidemic of childhood obesity as it can result in significant health consequences.”
