A “metabolic” injustice all too familiar... some lose excess weight with ease, while others, despite their efforts, see no change or even put on weight. How can such differences be explained? Better nutritional choices for some? More lengths in the pool for others? Better luck in the genetic lottery?
Nutrition, exercise, genetics...
The answer may instead lie in the gut microbiota. This is the hypothesis of researchers who followed 83 Chinese adults (72 of whom were overweight or obese) in a 6-month weight-loss program that involved recommended menus and daily exchanges with a dietician via smartphone. The aim was to reduce calories by 30% to 50%. Participants recorded their food intake several times a week, wore a sensor that calculated calories burned, and weighed themselves each Saturday. They also provided stool samples so that their microbiota and changes to it during the diet could be characterized. A saliva sample was also taken to determine their genetic predisposition to obesity.
...or the microbiota?
The results? Far more than diet, the level of physical activity or even genes, it was the initial gut microbiota that best predicted the weight curve during the study. The abundance of two bacteria, Blautia wexlerae and Bacteroides dorei, was found to be a particularly good predictor of future weight loss. Changes in weight during the diet were also accompanied by changes in the abundance of certain bacteria: Ruminococcus gnavus was significantly enriched in obese individuals and decreased in abundance during weight loss, whereas Akkermansia muciniphila and Alistipes obesi were significantly present in lean individuals and their abundance increased during dieting. The composition of our microbiota may thus predict our ability to lose weight, which could open the way to personalized nutritional programs that better target the microbiota. Could this be the end of metabolic inequalities?
