New Study Debunks the "Fat but Fit" Notion

January 28, 2021
Patrick Campbell

New research suggests increased BMI was associated with increased prevalence of cardiovascular disease risk factors regardless of a patient's physical activity levels.

This article was originally published on EndocrinologyNetwork.com.

An analysis of more than half a million patients is disputing the notion that patients can be ‘fat but fit’ by suggesting an increased body mass index (BMI) was associated with a greater risk of cardiovascular disease regardless of a patient’s physical activity levels.

Results of the study, which included data from more than 570,000 adult patients, demonstrate increased levels of physical activity were associated with lower risk of cardiovascular disease risk factors across all weight groups examined but also noted the impact of increased BMI on cardiovascular risk.

"One cannot be 'fat but healthy'," said study investigator Alejandro Lucia, MD, PhD, Professor at the European University in Madrid, Spain, in a statement. "This was the first nationwide analysis to show that being regularly active is not likely to eliminate the detrimental health effects of excess body fat. Our findings refute the notion that a physically active lifestyle can completely negate the deleterious effects of overweight and obesity.”

With recent research purporting increased cardiorespiratory fitness could reduce the negative impact of excess body weight on cardiovascular health, Lucia and a team of colleagues sought to further examine this notion in a large observational study. To do so, investigators designed their study to assess joint associations between multiple BMI categories and levels of physical activity, respectively, with prevalence of major cardiovascular disease risk factors using data from a cohort of patients insured by a large occupational risk prevention company in Spain.

In total, 572,662 individuals were included in the study. All participants included in the study were between 18-64 years of age and underwent annual medical examinations every year from 2012-2016. For the purpose of analysis, participants were categorized according to BMI, with normal weight considered 20-24.9 kg/m2, overnight considered 25-29.9 kg/m2, and obesity considered 30.0 kg/m2 or greater.

Investigators created 3 groups using WHO physical activity recommendations. These groups were defined as inactive, insufficiently active, and regularly active. Insufficiently active was defined as not meeting the WHO minimum recommendation of 150 minutes per week of moderate physical activity or 75 minutes per week of vigorous physical activity and regularly active was defined as meeting the WHO recommendations. Information related to prevalence of cardiovascular risk factors including diabetes, hypercholesterolemia, and hypertension from medical examination data.

Investigators used logistic regression to assess associations between BMI and physical activity groups with prevalence of cardiovascular disease risk factors. Of note, analyses were adjusted demographic/descriptive variables including date of the medical examination, and participants’ home address, age, sex, and smoking status.

Overall, 42% of patients were considered normal weight, 41% were considered overweight and 18% were obese. When assessing physical activity, 63.5% were considered inactive, 12.3% were considered insufficiently active, and 24.2% were considered regularly active. The most common risk factor (30%) was hypercholesterolemia, followed by hypertension (15%), and diabetes (3%).

Results of the investigators’ analysis indicated being insufficiently active or regularly active was associated with lower risks of diabetes and hypertension across all BMI categories. However, results also suggested being insufficiently active or regularly active did not compensate for the effects of being overweight or obese, with these individuals at a greater risk of cardiovascular than their peers with normal weight regardless of physical activity levels.

Investigators pointed out while results of the study underline the importance of weight loss, they also highlight the benefits of physical activity across all BMI categories.

"Fighting obesity and inactivity is equally important; it should be a joint battle. Weight loss should remain a primary target for health policies together with promoting active lifestyles,” said Lucia.

This study, “Joint association of physical activity and body mass index with cardiovascular risk: a nationwide population-based cross-sectional study,” was published in the European Journal of Preventive Cardiology.