Eating junk food may do a double whammy on your waistline: In addition to the calorie influx, high-fat foods alter intestinal bacteria, actually making it easier to get fat. Obese mice in a new study had significantly more of a specific type of bacteria, Firmicutes, that easily convert food into calories that can be absorbed by the body. In other words, the same diet resulted in higher caloric intake.
When researchers transferred a high proportion of Firmicutes into mice with no stomach bacteria, they gained more weight than those with proportionally more of the other predominant type of gut bacteria. And diet changes can switch on the flab-inducing bacteria: In mice who were fed a high-sugar, high-fat diet, the proportion of bacteria changed to favor Firmicutes within 24 hours, the Los Angeles Times reports.