How Antibiotics Affect Your Weight
It’s often said that there’s no miracle drug for weight loss. However, the same kind of medicine used to treat ear infections and strep throat could also be effective in helping us shed unwanted weight, according to a new University of Chicago study that examined how the immune system, gastrointestinal bacteria, and diet interact. The results suggest that weight gain may be linked to the types of bacteria present in the gut, meaning that bacteria-slaying antibiotics may someday join diet and exercise in the fight against obesity, according to study researcher Vaibhav Upadhyay of the University of Chicago MD-Ph.D. program.
In the study, normal mice and mice with a genetic defect that discourages the normal growth of bacteria in the gut were put on nine-week, high-fat diets. The normal mice gained weight, while the genetically-defective mice remained steady on the scale. Why? It seems that a particular kind or ratio of bacteria present in the tummies of normal mice (and people) help extract calories from food, which can then be stored as fat. Without this bacteria balance (which researchers have yet to identify) fewer calories can be absorbed and stored, prohibiting even a high-fat diet from causing weight gain.
How does bacteria get in the gut, in the first place?
Our immune systems are responsible for encouraging the growth of some kinds of bacteria (i.e., the kind that promotes weight gain) in the stomach in a process regulated by lymphotoxin, a molecule naturally produced by our bodies. We also eat some bacteria: Probiotics, a.k.a. healthy bacteria, are becoming an increasingly popular addition to supplements, as well as foods like probiotic yogurt.
Do antibiotics get rid of the bacteria that causes weight gain, and spur weight loss?
Because antibiotics can simultaneously inhibit the growth of some bacteria while promoting the growth of other bacteria, it’s believed antibiotics can be tailored to promote weight loss, Upadhyay says. Still, there are more than 500 different strains of bacteria present in the bowel, and the precise ones that inhibit weight gain need to be better established before they can be harnessed to fight fat. “Weight gain or loss is about fostering the right mix of bacteria in the gut,” he says, which explains why low-dose antibiotics have long been used in the livestock industry to make animals gain weight. (Discover one common cause of weight gain.)
Will eating probiotic foods make you fat?
Yes, no, maybe so. “It’s unclear if there is any correlation between the organisms [food manufacturers] add to their products and weight one way or another,” Upadhyay says. Again, more research is needed on the exact bacteria that are in play in the gut during both weight loss and weight gain. Once that relationship is established, probiotics (healthy bacteria) and prebiotics (their food) could be harnessed to fight fat, Upadhyay says.
Should you keep taking probiotics? It seems like just about everybody nowadays is taking probiotics—global sales of both probiotic supplements and foods that contain probiotics are expected to reach $31.1 billion by 2015, according to BCC Research. It’s for good reason: Even if they aren’t designed to aid in weight loss (yet), they still do a body good. Healthy bacteria in the gut provide enzymes that are necessary for the body to absorb many vitamins and minerals, and help you get the biggest nutritional bang per bite, he says. So, yes, keep you should keep the probiotics coming.
—Elizabeth Narins, Womenshealthmag.com
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