A new report, published in Nature Metabolism, is shedding light on the distinct and underappreciated role of fructose in driving disease, separate from its role as a simple source of calories.
Researchers examine how common dietary sweeteners, including table sugar (sucrose) and high-fructose corn syrup, impact human health. While both contain glucose and fructose, fructose has unique metabolic effects that may more directly contribute to obesity and related conditions.
“Fructose is not just another calorie,” said Richard Johnson, MD, professor at the University of Colorado Anschutz and study lead author. “It acts as a metabolic signal that promotes fat production and storage in ways that differ fundamentally from glucose.”
The report outlines how fructose metabolism bypasses key regulatory steps in the body’s energy-processing pathways. This can lead to increased fat synthesis, depletion of cellular energy (ATP) and the production of compounds linked to metabolic dysfunction. Over time, these effects may contribute to metabolic syndrome, a cluster of conditions that includes obesity, insulin resistance and cardiovascular risk.
Importantly, the authors emphasise that fructose’s impact extends beyond dietary intake alone. The body can also produce fructose internally from glucose, suggesting that its role in disease may be broader than previously recognised.
The findings come amid ongoing concern about rising rates of obesity and diabetes worldwide. Although some countries have seen declines in sugary beverage consumption, overall intake of “free sugars” remains above recommended levels in many regions and continues to increase in others.
While fructose may have once served an evolutionary purpose, helping the body store energy that can aid survival during times of food scarcity, the researchers argue that in today’s environment of constant food availability, these same mechanisms now contribute to chronic disease.
“This review highlights fructose as a central player in metabolic health,” said Johnson. “Understanding its unique biological effects is critical for developing more effective strategies to prevent and treat metabolic disease.”
Adolescents who consume more ultra-processed foods (UPFs) have significantly higher odds of being overweight or obese, according to a new systematic review and meta-analysis published in the open-access journal PLOS One by Mekuriaw Nibret Aweke of the University of Gondar, Ethiopia, and colleagues. In the most recent of the analysed studies, higher UPF consumption was linked with more than twice the odds of overweight or obesity compared to lower UPF consumption.
Being overweight or obese during adolescence raises a person’s likelihood of developing type 2 diabetes, high cholesterol, hypertension, and metabolic syndrome. The increasing consumption of UPFs – defined as industrial products made largely from extracted, modified, or synthetic ingredients, and typically high in added sugars, salt, unhealthy fats, and chemical additives – represents one of the fastest-growing unhealthy eating patterns among young people worldwide.
In the new study, researchers systematically searched multiple databases for observational studies reporting on UPF consumption and weight outcomes in adolescents aged 10 through 19. They identified 23 eligible studies involving a total of 155 000 adolescents, conducted across 16 countries between 2008 and 2025.
In a meta-analysis of all 23 studies, the researchers found that adolescents with higher UPF consumption had 63% greater odds of overweight or obesity compared with those with lower intake (OR = 1.63; 95% CI: 1.36–1.95). The positive association was consistent across all geographic regions studied, including Africa, Asia, Europe, North America, and South America. Subgroup analysis by year of publication showed that the most recent studies, published in 2024 and 2025, reported the highest odds ratio (OR = 2.09), suggesting the association may be growing stronger as UPF consumption rises globally.
Among other aspects, the study is limited by its reliance on observational designs, which cannot establish causation, and by variation across studies in how UPF consumption and obesity were measured.
The authors conclude that public health strategies should prioritize reducing UPF consumption among adolescents through education, policy interventions, and promotion of minimally processed, nutrient-dense foods.
The authors add: “Higher consumption of ultra-processed foods is linked to a substantially increased risk of overweight and obesity among adolescents, emphasising the need for early dietary interventions.”
“Improving adolescent nutrition today is essential to protecting long-term population health and reducing healthcare costs associated with obesity-related conditions.”
Just over one in 10 deaths from a wide range of infectious diseases are associated with obesity worldwide, finds a major new study led by a UCL researcher.
People with obesity face a 70% higher risk of hospitalisation or death from an infection than those of a healthy weight, suggest the findings published in The Lancet.
Obesity is linked to an increase in the risk posed by many different infectious diseases, from flu and COVID to stomach bugs and urinary tract infections, and the researchers found that the higher the BMI, the greater the risk.
The study’s lead author, Professor Mika Kivimaki (UCL Faculty of Brain Sciences), said: “Obesity is well known as a risk factor for metabolic syndrome, diabetes, cardiovascular disease, and many other chronic conditions. Here we have found robust evidence that obesity is also linked to worse outcomes from infectious diseases, as becoming very ill from an infection is markedly more common among people with obesity.”
The researchers studied data from over 540 000 people who participate in large cohort studies in the UK (the UK Biobank dataset) and Finland, to look at the relationship between obesity and severe infectious disease. Participants had their body mass index (BMI) assessed when they entered the studies and were then followed up for an average of 13-14 years.
The researchers found that people with obesity (defined as a BMI of 30 or higher) had a 70% higher risk of hospitalisation or death from any infectious disease in the study period compared to people with a BMI between 18.5 to 24.9 (classified as a healthy weight).
The risk increased steadily as body weight increased. People with a BMI of 40 or higher had three times the severe infection risk compared to people with a healthy weight.
The link between obesity and severe infections was consistent regardless of the measure of obesity used (BMI, waist circumference, or waist-to-height ratio, where data was available) and for a wide range of infection types.
The study included data on 925 bacterial, viral, parasitic, and fungal infectious diseases, and the authors also honed in on 10 common infectious diseases in more detail. For most of these diseases, including flu, Covid-19, pneumonia, gastroenteritis, urinary tract infections, and lower respiratory tract infections, they found that people with obesity were more likely to be hospitalised or die than people with a healthy BMI. However, obesity did not appear to increase the risk of severe HIV or tuberculosis.
The analysis found that the link to severe infections was not explained by obesity-related chronic conditions, as the association was consistent in people with obesity who did not have metabolic syndrome, diabetes, or heart disease, while the association was also not explained by lifestyle factors such as physical activity.
While the study did not investigate the causes of the association, the researchers say that previous studies have suggested that obesity contributes to a general impairment of immune function, including immune dysregulation, chronic systemic inflammation, and metabolic disturbances.
Professor Kivimaki said: “Our findings suggest that obesity weakens the body’s defences against infections, resulting in more serious diseases. People may not get infected more easily, but recovery from infection is clearly harder.”
The researchers found evidence that losing weight can reduce the risk of severe infections as people with obesity who lost weight had a roughly 20% lower risk of severe infections than those who remained obese.
First author Dr Solja Nyberg (University of Helsinki) commented: “As obesity rates are expected to rise globally, so will the number of deaths and hospitalisations from infectious diseases linked to obesity.
“To reduce the risk of severe infections, as well as other health issues linked with obesity, there is an urgent need for policies that help people stay healthy and support weight loss, such as access to affordable healthy food and opportunities for physical activity. Furthermore, if someone has obesity, it is especially important to keep their recommended vaccinations up to date.”
The authors used infectious disease mortality data from the Global Burden of Diseases (GBD) Study to model the impact of obesity on infectious disease deaths for different countries, regions and globally.
The analysis suggested 0.6 million out of 5.4 million (10.8% or one in 10) infectious diseases deaths globally were linked with obesity in 2023.
The researchers estimated that in the UK, one in six (17%) infection-related deaths can be attributable to obesity, and 26% in the US.
Co-author Dr Sara Ahmadi-Abhari (Imperial College London), who conducted the Global Burden of Diseases (GBD) analyses, said: “Estimates of the global impact give a sense of how large the problem may be, but they should be interpreted with caution. Data on infection-related deaths and obesity in the GBD are not always accurate, particularly in low-resource countries.”
A University of Exeter-led study has quantified the role of obesity in common long-term conditions, showing for the first time the effect of losing weight in preventing multiple diseases.
Conditions that often occur together may share an underlying cause, which can be key to prevention or treatment. The picture of which conditions co-occur is complex, so researchers paired them together, to allow them to identify shared causes more simply. The study found that obesity is the main shared cause between ten pairs of commonly occurring conditions.
The research specifically measured how much weight reduction would reduce the risk of the next diagnosis. In the largest study of its kind, published in Communications Medicine – Nature, the team studied 71 conditions which often occur together, such as type 2 diabetes and osteoarthritis, or kidney disease and chronic obstructive pulmonary disease (COPD).
The GEMINI study, funded by the UKRI Medical Research Council and supported by the National Institute for Health and Care Research (NIHR), used genetics and healthcare data drawn from a number of large datasets internationally. They found that obesity was part of the cause for 61 of the 71 conditions. They also found that obesity explained all of the genetic overlap in ten pairs of conditions, suggesting it is the main driver for why they frequently occur together.
Body mass index, or BMI, is a scaled measure of weight – a number over 30 units indicates obesity, while less than 25 indicates “normal” weight. The study quantified how much a reduction in BMI would reduce the risk of both conditions at a population level for people overweight or living with obesity. For example, for every thousand people who have both chronic kidney disease and osteoarthritis, a BMI reduction of 4.5 units would have prevented 17 of them developing both conditions or nine people per thousand with type 2 diabetes and osteoarthritis.
The team also established the pairs of conditions where obesity is not the main cause and are now investigating other mechanisms.
Study lead Professor Jack Bowden, at the University of Exeter Medical School: “We’ve long known that certain diseases often occur together, and also that obesity increases the risk of many diseases. This largescale study is the first to use genetics to quantify the role of obesity in causing diseases to occur in the same individuals. We found that for some disease pairings, obesity is the major driving force. Our research provides much more detail about the links between obesity and disease, which will help clinicians target specific advice to patients going forward.”
Study author Professor Jane Masoli, of the University of Exeter Medical School, who is a Consultant Geriatrician and regional NIHR Ageing lead, said: “Currently nine million people in the UK live with two or more long-term conditions. Understanding how to prevent diseases accumulating is a key national research and healthcare priority. This study further strengthens the case to tackle obesity through public health programmes, reinforcing the importance of lifelong obesity management in the NHS strategy on prevention. Our work shows that this could reduce the risk of accumulating multiple health conditions, supporting people to live longer, healthier lives.”
This research represents another important publication from the GEMINI (Genetic Evaluation of Multimorbidity towards INdividualisation of Interventions) collaborative. Led by the University of Exeter, GEMINI includes people with multimorbidity, health care professionals including those in primary care and experts in statistics and genetics, and was one of six programmes funded by the UKRI strategic priorities fund, an £830 million investment in multimorbidity research.
The GEMINI team are working to further understand why some conditions more frequently co-occur in the same patients. The team are quantifying the role of other, known modifiable risk factors beyond obesity, and are finding novel genes and pathways that could point to new ways to intervene and improve health. GEMINI data, results, and code are free to download (https://github.com/GEMINI-multimorbidity), and the pairwise genetic and observational correlations can be viewed interactively (https://gemini-multimorbidity.shinyapps.io/atlas/).
Changing the amount of sweetness in a person’s diet has no impact on their liking for sweet foods, the results of a new trial suggest. The results also showed no difference in indicators of cardiovascular disease or diabetes risk between people who increased or decreased their intake of sweet-tasting foods over a six-month period.
The research team suggest that consequently public health organisations may need to change their current advice on reducing sweet food consumption to tackle the obesity crisis.
The study, published in the American Journal of Clinical Nutrition, was carried out by Wageningen University and Research in the Netherlands and Bournemouth University in the UK.
“People have a natural love of sweet taste which has led many organisations, including the World Health Organisation, to offer dietary advice on reducing the amount of sweetness in our diets altogether,” said Katherine Appleton, Professor in Psychology at Bournemouth University and corresponding author for the study. “However, our results do not support this advice, which does not consider whether the sweet taste comes from sugar, low calorie sweeteners, or natural sources.” she added.
During the trial, 180 participants were split into three groups. One group consumed a diet containing a high amount of sweet-tasting food, a second group consumed a low amount and a third consumed an average amount. The sweetness in the foods provided for their diets came from a combination of sugar, natural sweetness or low-calorie sweeteners.
After one, three and six months, participants were surveyed on whether their liking and perception of sweet foods had changed. They were also weighed and provided blood and urine samples to measure any changes in their diabetes risk and cardiovascular health.
At the end of the trial, the researchers found no significant differences in any of the measures across the three groups. Participants also reported a spontaneous return to their previous intake of sweet foods after the six months.
Based on their results, the study team are recommending that public health organisations may need to change their current advice on reducing sweet foods to tackle overweight and obesity.
“It’s not about eating less sweet food to reduce obesity levels,” Professor Appleton said. “The health concerns relate to sugar consumption. Some fast-food items may not taste sweet but can contain high levels of sugar. Similarly, many naturally sweet products such as fresh fruit and dairy products can have health benefits. Public advice therefore needs to concentrate on how people can reduce the amount of sugar and energy-dense foods they consume,” she concluded.
Underweight patients may face higher risk of poor outcomes after surgery
Source: Pixabay CC0
Higher BMI is not linked to increased risk of death or other complications following shoulder replacement surgery, according to a new study by Epaminondas Markos Valsamis from the University of Oxford, UK, and colleagues publishing November 20th in the open-access journal PLOS Medicine.
Joint replacement surgeries – including hip, knee and shoulder replacements – can significantly improve quality of life. Many patients with obesity are denied these procedures despite a lack of formal recommendations from national organisations. Evidence on the risks of joint replacement surgery in patients with obesity is limited and mixed.
In this study, researchers analysed more than 20 000 elective shoulder replacement surgeries performed across the UK and Denmark to see whether BMI was associated with death or other complications.
Compared to patients with a healthy BMI (21.75 kg/m2), patients with obesity (BMI 40 kg/m2) had a 60% lower risk of death within the year following surgery. Those considered underweight (BMI <18.5 kg/m2) had a slightly higher risk of death. The study does not support restricting patients with a high BMI from having elective shoulder replacement surgery, contrary to evidence that some hospitals are starting to restrict patients.
One main limitation of this study was the small sample size of the underweight population (131 for the UK data, 70 for the Denmark data). However, this was a large study that consistently showed a lower risk of death and complications in patients with obesity undergoing shoulder replacement surgery across multiple outcomes and two countries. The results can help patients, surgeons, and policymakers make informed decisions about who should be considered fit for these surgeries.
Lead author Epaminondas Markos Valsamis says, “Shoulder replacements offer patients the opportunity for excellent pain relief and improved quality of life. Our research shows that patients with a higher BMI do not have poorer outcomes after shoulder replacement surgery.”
Senior author Professor Jonathan Rees adds, “While BMI thresholds have been used to limit access to joint replacement surgery, our findings do not support restricting higher BMI patients from accessing shoulder replacement surgery.”
An illustration showing how Sirona works. Image credit: Oxford Medical Products
An innovative new pill could soon offer a new and affordable weight management treatment, following a successful clinical trial involving University of Bristol researchers and supported by the National Institute for Health and Care Research (NIHR). The results are published in the journal Obesity.
Sirona by Oxford Medical Products is a hydrogel-based pill that is designed to aid weight loss by reducing hunger. After it is swallowed, the pill expands in the stomach, leading to faster satiety. This helps individuals to eat less without needing strong medications or injections.
In the trial, funded by Innovate UK, participants lost up to 13.5% of their body weight in just six months. On average, people with class 1 obesity (BMI 30-35) lost 6.4% of their body weight.
Participants also ate on average 400 fewer calories per day compared to those taking a placebo. For context, recent Government-led research suggests that even a 216-calorie daily reduction could cut the UK’s obesity rate in half.
Mr Byrne, a consultant surgeon at University Hospital Southampton, said: “Obesity is a chronic and often progressive disease. With obesity rates continuing to rise, these results are an important step towards providing a different treatment option.
“This trial demonstrated Sirona could be a safe, affordable, and non-pharmacological treatment to support long-term weight management.”
Sirona will be accessible to anyone with a BMI 25-40, which means Sirona is particularly well-suited to help two key patient types. Firstly, for patients with an overweight BMI (25–30), allowing them to proactively manage their weight and to avoid progressing into obesity and the serious health problems it can bring. Secondly, it is suitable for use as an ‘off-ramp’ for GLP-1 users looking to come off treatment but prevent weight regain, which often occurs once GLP-1 medication ceases.
GLP-1 medications have become very popular for weight loss, with around 1.5 million users in the UK. However, a significant proportion of users pay out of pocket and prices have recently doubled in the UK for some doses of Mounjaro.
Camilla Easter, CEO of Oxford Medical Products, added: “GLP-1 medications perform an important role in helping those with a BMI in the obese range to lose weight and reduce weight-related health risks. There is, however, a real opportunity for a new style of treatment to work in a complementary way to GLP-1s, in a format that is significantly less expensive, and with better tolerability and therefore more accessible for the majority.
“Sirona has demonstrated amazing results during testing with UK hospitals, which have now been externally peer-reviewed. Next, we are setting sights on commercial UK release plans, targeting 2027 to make Sirona available.”
Sirona is a dual-polymer hydrogel pill. That means it’s made from two types of safe materials that expand in the stomach. It doesn’t use drugs or chemicals to change how your body works.
The pill was well tolerated during the 24-week study. There were no serious adverse events. Participants lost up to 13.5% of their body weight in just 24 weeks, and individuals with class 1 obesity (BMI 30-35) lost 6.4% of their body weight on average.
Importantly, no serious adverse events were reported during the trial. Sirona was well tolerated (95 percent of patients adhered to the dosing regimen at 12 weeks) and demonstrated a fantastic safety and side effect profile. This makes Sirona appropriate for patients who have struggled with adverse side effects when using GLP-1 medications.
OMP is planning a pivotal study in the UK and USA to further assess the effectiveness of Sirona and confirm these results. The novel weight loss treatment will aim for a 2027 UK commercial launch.
Mom’s genes play a larger role than dad’s in determining whether kids will be obese
A new study finds that kids with obesity are more likely to have obese parents because they inherit obesity-related genes, and to a smaller extent, are impacted indirectly by genes carried by the mother – even when those genes aren’t passed down. A new study led by Liam Wright of the University College London, UK, and colleagues, reports these findings August 5th in the open-access journal PLOS Genetics.
Studies commonly show that children with obesity often have parents with obesity, but the cause of this trend has been poorly understood. Children may inherit genes from their parents that increase their risk of obesity, or they could be shaped by conditions in the womb, or by the food and lifestyle choices their parents make.
In the new study, researchers investigated the effects of the parents’ genetics on the weight and diet of their children. They looked at a measure of obesity called the body mass index (BMI), along with the diet and genetic data from more than 2500 mother-father-child trios. They focused on obesity related genes in the parents – both the ones that were directly passed down to their children, and the genes that weren’t, but that may indirectly impact weight by shaping the child’s environment, which are called genetic nurture effects. They found that, though mothers’ and fathers’ BMIs were consistently correlated with the child’s BMI, this trend could be mostly explained through the genes that children directly inherit. Genetic nurture effects from obesity-related genes in the mother that were not inherited had a smaller impact, only during the child’s adolescence.
The results suggest that a mother’s BMI may be particularly important for determining a child’s BMI, both due to the effects of genes that children directly inherit, and through indirect nurture effects from genes that weren’t passed down. Meanwhile, fathers had little impact on their child’s BMI, apart from the genes that were directly inherited. The study’s authors suggest that analyses that don’t consider the inherited genes are likely to give misleading estimates of the parents’ influence on a child’s weight.
The authors add, “Our results suggest mother’s weight could affect their children’s weight; policies to reduce obesity could have intergenerational benefits.”
Children born to obese mothers are at higher risk of developing metabolic disorders, even if they follow a healthy diet themselves. A new study from the University of Bonn published in the journal Nature offers an explanation for this phenomenon. In obese mice, certain cells in the embryo’s liver are reprogrammed during pregnancy. This leads to long-term changes in the offspring’s metabolism. The researchers believe that these findings could also be relevant for humans.
The team focused on the so-called Kupffer cells. These are macrophages that help protect the body as part of the innate immune system. During embryonic development, they migrate into the liver, where they take up permanent residence. There, they fight off pathogens and break down ageing or damaged cells.
“But these Kupffer cells also act as conductors,” explains Prof Dr Elvira Mass from the LIMES Institute at the University of Bonn. “They instruct the surrounding liver cells on what to do. In this way, they help ensure that the liver, as a central metabolic organ, performs its many tasks correctly.”
Changing the tune: From Beethoven to Vivaldi
It appears, however, that it is this conducting function that is changed by obesity. This is what mouse experiments carried out by Mass in cooperation with other research groups at the University of Bonn suggest. “We were able to show that the offspring of obese mothers frequently developed a fatty liver shortly after birth,” says Dr Hao Huang from Mass’s lab. “And this happened even when the young animals were fed a completely normal diet.”
The cause of this disorder seems to be a kind of “reprogramming” of the Kupffer cells in the offspring. As a result, they send out molecular signals that instruct the liver cells to take up more fat. Figuratively speaking, they no longer conduct one of Beethoven’s symphonies but rather a piece by Vivaldi.
This shift already seems to occur during embryonic development and is triggered by metabolic products from the mother. These activate a kind of metabolic switch in the Kupffer cells and change the way these cells direct liver cells in the long term. “This switch is a so-called transcription factor,” says Mass. “It controls which genes are active in Kupffer cells.”
No fatty liver without the molecular switch
When the researchers genetically removed this switch in the Kupffer cells during pregnancy, the offspring did not develop a fatty liver. Whether this mechanism could also be targeted with medication is still unclear. The teams now plan to investigate this in follow-up studies.
If new treatment approaches emerge from this, it would be good news. The altered behaviour of the Kupffer cells likely has many negative consequences. Fat accumulation in the liver, for example, is accompanied by strong inflammatory responses. These can cause increasing numbers of hepatocytes to die and be replaced with scar tissue, resulting in fibrosis. At the same time, the risk that hepatocytes degenerate and become cancerous increases.
“It is becoming ever more evident that many diseases in humans already begin at a very early developmental stage,” says Mass, who is also spokesperson for the transdisciplinary research area “Life & Health” and a board member of the “ImmunoSensation2” Cluster of Excellence at the University of Bonn. “Our study is one of the few to explain in detail how this early programming can happen.”
Intermittent energy restriction, time-restricted eating and continuous energy restriction can all improve blood sugar levels and body weight in people with obesity and type 2 diabetes, according to a study being presented Sunday at ENDO 2025, the Endocrine Society’s annual meeting in San Francisco, Calif.
“This study is the first to compare the effects of three different dietary interventions intermittent energy restriction (IER), time-restricted eating (TRE) and continuous energy restriction (CER) in managing type 2 diabetes with obesity,” said Haohao Zhang, PhD, chief physician at The First Affiliated Hospital of Zhengzhou University in Zhengzhou, China.
Although researchers identified improved HbA1c levels, and adverse events were similar across the three groups, the IER group showed greater advantages in reducing fasting blood glucose, improving insulin sensitivity, lowering triglycerides, and strengthening adherence to the dietary interventions.
“The research fills a gap in directly comparing 5:2 intermittent energy restriction with a 10-hour time-restricted eating in patients with obesity and type 2 diabetes. The findings provide scientific evidence for clinicians to choose appropriate dietary strategies when treating such patients,” Zhang says.
Zhang and colleagues performed a single-centre, randomised, parallel-controlled trial at the First Affiliated Hospital of Zhengzhou University from November 19, 2021 to November 7, 2024.
Ninety patients were randomly assigned in a 1:1:1 ratio to the IER, TRE or CER group, with consistent weekly caloric intake across all groups. A team of nutritionists supervised the 16-week intervention.
Of those enrolled, 63 completed the study. There were 18 females and 45 males, with an average age of 36.8 years, a mean diabetes duration of 1.5 years, a baseline BMI of 31.7kg/m², and an HbA1c of 7.42%.
At the end of the study, there were no significant differences in HbA1c reduction and weight loss between the IER, TRE and CER groups. However, the absolute decrease in HbA1c and body weight was greatest in the IER group.
Compared to TRE and CER, IER significantly reduced fasting blood glucose and triglycerides and increased the Matsuda index, a measure of whole-body insulin sensitivity. Uric acid and liver enzyme levels exhibited no statistically significant changes from baseline in any study group.
Two patients in the IER group and the TRE group, and three patients in the CER group, experienced mild hypoglycemia.
The IER group had the highest adherence rate (85%), followed by the CER group at 84% and the TRE group at 78%. Both the IER and CER groups showed statistically significant differences compared with the TRE group.
Zhang said these findings highlight the feasibility and effectiveness of dietary interventions for people who have obesity and type 2 diabetes.
