New Spanish research casts doubt on the “fat but fit” paradox, where it is thought that physical fitness is enough to eliminate cardiovascular disease (CVD) risk.
Overweight and obesity is a worldwide problem that is greatly contributing to the burden of noncommunicable diseases, including CVD. A high body mass index (BMI) is strongly associated with CVD risk factors, such as hypercholesterolaemia, hypertension and diabetes. The cardiovascular complications arising from overweight and obesity are driven by processes such as inflammation, insulin resistance, endothelial dysfunction, coronary calcification. Some evidence suggested that physical activity was cardioprotective, partly or completely eliminating the CVD risk from disease – the “fat but fit” paradox.
A recent meta-analysis showed that cardiovascular fitness was a better predictor of cardiovascular disease over overweight/obesity, suggesting that perhaps public health programmes should emphasise fitness over control of body weight. To this end, the researchers sought to confirm if the “fat but fit” paradox was real.
The researchers gathered data from workers’ health insurance, with participants aged 18-64 grouped into normal weight, overweight and obesity by BMI, and into regularly active ( >150 min moderate physical activity or equivalent per week), insufficiently active (less than regularly active) and inactive (no physical activity at all). They were further separated by age, sex, smoking status and residential address.
Approximately 42%, 41%, and 18% of participants had normal weight, overweight, or obesity, respectively; 63.5%, 12.3%, and 24.2% were inactive, insufficiently active, and regularly active; and 30%, 15%, and 3% had hypercholesterolaemia, hypertension, and diabetes.
However, the protective effect of physical activity was far less than the excess risk from overweight/obesity. So much so that even regularly active obese participants had two to five-fold risk increases over their inactive but normal weight peers in the risk factors.
The protective effect of physical activity in overweight/obesity remains controversial. Shortcomings of the study were that they did not control for diet, and only accounted for self-reported leisure time activities. However, the large study size, with over 500 000 participants, should put paid to the theory that a physically active lifestyle can completely eliminate the deleterious effects of overweight/obesity.
The researchers concluded that, “weight loss per se should remain a primary target for health policies aimed at reducing CVD risk in people with overweight/obesity.”
Journal article source: European Journal of Protective Cardiology
Journal information: Pedro L Valenzuela, et al., Joint association of physical activity and body mass index with cardiovascular risk: a nationwide population-based cross-sectional study, European Journal of Preventive Cardiology, 2021;, zwaa151, https://doi.org/10.1093/eurjpc/zwaa151
