Scientists believe bacteria in our gut can influence weight gain or loss
Efficiency of bacteria that break down what we eat may affect efforts to trim our waistlines
In 2008, Rob Knight fell ill while holidaying in Peru. Camping along the Inca Trail, he found himself with the usual traveller's symptoms, scrambling for the latrine in the middle of the night.
He took antibiotics for five days and got better, but then relapsed. A second five-day course of the drugs finally knocked out the infection.
After he returned home to America, Knight resumed his normal diet and exercise, and suddenly began dropping pounds that he had been trying to shed for years. He is convinced the antibiotics changed the composition of the microbes in his gut in a way that finally caused him to lose weight, about 30kg.
"Exercise and diet, which had not worked before, began to work," says Knight, a professor of chemistry and biochemistry at the University of Colorado at Boulder who studies the microorganisms that live in our bodies, known as the human microbiome. "I think that reconfiguring my gut microbial community made it possible."
His experience underscores a growing body of evidence suggesting that naturally occurring bacteria and other microbes in the body, and possibly even viruses, can influence weight in ways that scientists are only just beginning to understand. Numerous studies are under way looking at the role of intestinal organisms in obesity, with a focus on how they extract energy from food and how this affects weight gain or loss.
Ultimately, scientists say, insights gained from the research could identify people predisposed to obesity and possibly help clinicians create targeted weight-loss treatments for them. The specific composition of microbes in the intestines might also help predict the best candidates for weight-loss surgery, which doesn't work for everyone.