Longevity Briefs: Does Being Overweight Make You Age Faster?

Longevity briefs provides a short summary of novel research in biology, medicine, or biotechnology that caught the attention of our researchers in Oxford, due to its potential to improve our health, wellbeing, and longevity.

The Problem:

Previous studies have shown that being overweight is associated with shorter telomere length. Telomeres are protective caps at the ends of chromosomes that shorten each time a cell divides. Shortened telomeres are associated with increased mortality as well as various age-related diseases including diabetes, Alzheimer’s and cardiovascular diseases. 

While telomere shortening is widely acknowledged to be an important hallmark of ageing, Body Mass Index or BMI (your weight in kg divided by your squared height in metres) fails to accurately reflect body composition changes related to ageing because it doesn’t distinguish between fat and muscle mass. A recently proposed alternative metric is Weight-Adjusted-Waist Index (WWI), which is calculated by dividing your waist circumference by the square root of your body weight. This gives us a measurement of abdominal fat that is independent of weight, lean or otherwise.

The Discovery:

This study examined data from 3,479 participants from the National Health and Nutrition Examination Survey (NHANES), and uncovered a significant relationship between higher WWI and shorter telomere length within participants’ white blood cells. Interestingly, after controlling for covariates like age, gender and smoking habits, this relationship was an inverted U-shaped curve – both high and low WWI were associated with shorter telomeres, with an optimal WWI of about 10 cm/√kg being associated with the longest telomere length.

The Implications: 

This research reinforces the link between obesity and accelerated ageing, while also suggesting that maintaining WWI within an optimal range could promote healthy ageing. The WWI provides a more accurate assessment of obesity-related health risks than BMI and could potentially guide individuals in making lifestyle choices that promote longevity. 

However, it’s important to keep in mind that this study was observational in nature, which means that it only shows that people who had high or low WWI also had shorter telomeres, not that low or high WWI caused telomere shortening. For example, it’s possible that some underlying health condition or nutrient deficiency is causing both telomere shortening and low WWI. Another possible contributor is steroid abuse, which may lead to high lean mass relative to waist circumference while also leading accelerated ageing. It’s therefore not certain that deliberately maintaining your WWI within a certain range would be beneficial, though avoiding high WWI is a pretty safe bet given what we know about the perils of visceral fat tissue. It’s also worth pointing out that while telomeres certainly seem to be involved in the ageing process, it’s not clear to what extent maintaining telomere length in humans actually translates to slower ageing.