Why are some people fat? It’s not just a question that fat people ask themselves, but also one that drives much medical research because obesity increases the risk of serious illnesses including heart disease and diabetes.
A study recently published in Science adds gut bacteria to the list of possible causes of obesity.
The intestine is home to trillions of microbes that help the body break down and use food. The particulars of the mix have been found to vary significantly from person to person, even among identical twins.
In an effort to isolate the contribution of gut bacteria to weight, researchers led by Jeffrey Gordon, of Washington University in St. Louis took the bacteria from pairs of identical and fraternal twins, each with one obese twin and one lean, and put it in previously germ-free cloned mice. (We glossed tastefully over the matter of the fecal transplant.)
The results indicate that bacteria does in fact play a powerful role: The mouse that got the obese twin’s bacteria grew fat and developed metabolic problems linked to insulin resistance, even when fed only low-fat mouse chow.