It’s a paradox: even though the obesity epidemic is taking on alarming proportions, particularly in France, where one inhabitant in two is affected, a series of studies tend to show that moderate overweight has a protective effect when we advance in age, with, in particular, a reduction in mortality. An analysis of the scientific literature carried out a few years ago by Australian researchers noted that seniors with a body mass index (BMI) slightly higher than official WHO recommendations (BMI between 18.5 and 25) lived longer. Specifically, the risk was lower if their BMI was 27.5, compared to those in the “normal” range of 20-21; and that marking obesity, greater than 33. In total, according to these researchers, people over 65 with a BMI between 23 and 33 are the best placed from the point of view of longevity. On the men’s side, other studies point out that moderate adiposity, including when it is abdominal, has a positive effect on longevity and that, above all, being thin is clearly unfavorable to the health of older men.
How to understand these results? Knowing that the deleterious effects of weight gain on health are well known: increased risk of cardiovascular disease; type 2 diabetes; certain cancers; joint problems… In addition, an elderly person who has mobility problems is all the more likely to suffer with increasing weight. So should we go on a diet, when the prevalence of obesity among 65-70 year olds is around 20%? “It’s all about measurement and customization. To each his own needs, to each his nutritional recommendations”, underlines a Parisian specialist. “I see 75-year-old ladies in my office who want to lose weight because they’ve done it all their lives. But if the overweight is moderate, that is to say that they are in no way obese with a BMI greater than 30, I tell them what is most important is to preserve their muscular capital, to fight osteoporosis, stay dynamic, avoid falls…”
Because when you lose weight, you lose muscle, especially when the restrictive diet is not accompanied by a good level of physical activity. This explains why lean people, with a BMI of less than 20, have a higher risk of mortality than others, who are more enveloped. Too restrictive a diet can make a person vulnerable when struck by a serious illness. On the other side of the scale, obesity is just as deleterious with too much fat mass which leads the individual to move less, and therefore also to sarcopenia. It is therefore preferable, taking into account sarcopenia, to be slightly overweight than underweight, or at a so-called ideal weight but having lost muscle.
How then to be in the right bracket? It is advisable to keep a balanced diet, and to force on the proteins guaranteeing the maintenance of the muscular capacities, without forgetting the physical activity adapted to each one.
The latest figures for overweight and obesity in France, made public last February, are not good. If the prevalence of overweight fluctuates without much change around 30%, that of obesity continues to increase at a rapid rate. It thus fell from 8.5% in 1997 to 15% in 2012 and 17% in 2020. In terms of age groups, seniors are more overweight or obese than younger people: excess weight affects 57.3 % of 65+ vs. 23.2% of 18-24 year olds. Nevertheless, it is among the youngest that the increase in the prevalence of obesity over the years is the strongest. As for gender differences, in 2020 men are more often overweight than women (36.9% versus 23.9%), but the reverse is true for obesity. There are 17.4% obese among women compared to 16.7% among men.
