A recent study links excess belly fat to a higher risk of early death from any cause, with fat around the hips and thighs showing a lower risk.
Body Mass Index (BMI) is frequently used to work out if your weight is healthy. It measures weight in relation to height. However, it is widely questioned as an appropriate measure of obesity because it does not differentiate between lean body mass and fat mass. Therefore, inaccurate assessment of excess fat/obesity can occur.
Being obese is already known to be linked to a greater risk of several health problems such as heart disease and certain cancers. Previous research suggests that excess abdominal fat has a stronger association with the risk of death than overall obesity. This is because excess abdominal fat is known to secrete pro-inflammatory substances and is associated with increased dyslipidemia (abnormal amount of fats like cholesterol in the blood) and cardiovascular disease. Considering this evidence, researchers decided to examine whether excess abdominal fat measures are associated with a higher risk of all-cause mortality in the general population.
Published in the BMJ, researchers reviewed 72 prospective cohort studies, which included over 2.5 million participants, monitoring them for a range of 3-24 years. The studies all reported risk estimates for at least three central fat measures, including; waist circumference, hip circumference, thigh circumference, waist-to-hip ratio, waist-to-height ratio, waist-to-thigh ratio and body adiposity index, and a body shape index.
The results showed central fatness measures, including; waist circumference, waist-to-hip ratio, waist-to-height ratio, waist-to-thigh ratio, body adiposity index, and ‘A’ body shape index were significantly associated with higher all-cause mortality risk. The study showed that for each 10 cm increase in waist circumference, there was an 8% (men) and a 12% (women) higher risk of all-cause mortality.
However, researchers found that people who store fat on the hips and thighs, rather than the abdomen, were associated with a lower risk of all-cause mortality. Results showed that each extra 5cm thigh circumference was associated with an 18% reduced risk of death. According to researchers, the deposition of fat in the hip and thigh region is thought to be associated with better lipid and glucose profiles – which might have protective effects against cardiovascular and metabolic risk.
The associations remained significant even after accounting for BMI. This indicates that excess abdominal fat, independent of overall obesity, is associated with a higher risk of mortality. The results suggest that central fatness measures could be used alongside BMI to determine the risk of premature death. So, although fat is an essential part of maintaining good metabolic health, where it is stored can have different health consequences. Unfortunately, if you are a person that naturally stores fat around the abdomen, it may be harder to maintain good health. However, is important to remember is that body shape is only one risk factor, and a healthy diet, lifestyle, and exercise regime can lower the risk of chronic disease.
Written by Helen Massy, BSc.
References:
Després, J., & Lemieux, I. (2006). Abdominal obesity and metabolic syndrome. Nature, 444(7121), 881-887. https://doi.org/10.1038/nature05488
Jayedi, A., Soltani, S., Zargar, M., Khan, T., & Shab-Bidar, S. (2020). Central fatness and risk of all cause mortality: systematic review and dose-response meta-analysis of 72 prospective cohort studies. BMJ, m3324. https://doi.org/10.1136/bmj.m3324
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