Do people who are a little fat live longer? The Truth About the 'Obesity Paradox'

The Truth About the 'Obesity Paradox'

Have you heard of the study "The Obesity Paradox," published in the 2013 edition of the Journal of the American Medical Association (JAMA), which found that being overweight has a lower mortality rate than being of normal weight? The study looked at the correlation between body weight and mortality. Overweight people had a 6% reduction in mortality compared to those who were of normal weight.

However, this 'paradox of obesity' can have the dangerous consequence of promoting the development of obese populations by giving indulgences to overweight. That's because there's a big hole in that research.

The flaw in this study is that it looked at the relationship between BMI, or body mass index, and mortality. BMI has the advantage of being a relatively easy way to assess obesity using height and weight alone, but it has a number of weaknesses. The most common of these is that when a person is overweight for their height and numerically overweight, they cannot tell whether it is because they have a lot of fat or a lot of muscle.

The key is 'muscle mass'

The reason why being overweight has a lower mortality rate than being of normal weight is that muscle mass is beneficial for longevity. Loss of muscle mass results in a decrease in metabolic capacity, which increases the risk of dying from complications. In other words, normal weight people have a higher mortality rate than overweight because they have less fat, but because they need less muscle mass.

This is more pronounced as a problem in the elderly. As we age, we lose muscle mass, so you may have less muscle mass even if your BMI is the same as when you were younger. Therefore, it is preferable to interpret the obesity paradox research results by focusing on the relationship between muscle mass and mortality, rather than focusing on the relationship between body weight and mortality.