Emerging science suggests that your gut microbiota—the community of microbes (a.k.a bacteria) that live in your digestive tract—may affect your weight-loss efforts. Why? Your body contains hundreds of different species of beneficial bacteria, necessary to digest food into usable energy. But while some bugs are good, others are not-so-good, and the types and levels of each may alter your metabolism, potentially making it more difficult to stay thin. "The interplay of gut bacteria with your body will impact how your body uses food for energy," explains Julie Woodman, Ph.D., assistant professor of biology at Colorado Christian University.
A newly published study in the International Society for Microbial Ecology Journal confirms a link between gut microbiota and weight gain. Mice implanted with gut microbes taken from obese humans gained more weight than those implanted with bacteria from normal-weight humans, despite both groups of mice being fed the same diet.
Other studies have shed light on the ways in which gut microbiota makeup may affect weight gain and obesity. "People who are obese tend to have fewer gut microbial genes than lean individuals," explains Meghan Jardine, R.D., C.D.E., associate director of diabetes nutrition education at the Physicians Committee for Responsible Medicine. "Certain bacteria can either enhance metabolism or slow it down, so altered microbiota in obesity may contribute to increased fat storage."
In addition to potentially affecting your metabolism, the microbes in your gut can play a role in a wide range of other body functions. "Gut bacteria aid in immune function, digestion of food, and synthesis of certain vitamins and amino acids," Jardine explains. So it only makes sense that research has linked poor gut microbiota to several chronic diseases and health conditions, including diabetes and hypertension. However, gut bacteria have not been proven to directly cause these conditions, and there may be other factors at play.
What is known is that there are many things—including the food you eat—that can alter (for better or for worse) your gut bacteria composition. "Nutrition plays a prominent role in the makeup of the microbiota," explains Jardine. "Other potential contributors include stress, exercise, antibiotic exposure and hygiene."
What you feed your body, in essence, goes on to feed the bacteria in your digestive tract, so altering what you eat can change which bacteria thrive or perish. "Prebiotics are 'bacteria food,' as they contain the nutrients that good bacteria in your body need to flourish," explains Woodman. Foods high in fiber (think whole grains, beans, fruits and vegetables) are good sources of prebiotics; a couple standouts are onions and garlic. Woodman also underlines the importance of probiotics, explaining "probiotics populate your gut with good bacteria, giving your system a better chance of keeping bad bacteria at bay." Many dairy products, including yogurt and kefir, are rich in probiotics. Tempeh, kombucha tea and fermented or pickled fruits and vegetables (like sauerkraut and kimchi) are good plant-based sources of probiotics.
In addition to including prebiotics and probiotics in your diet, other food choices can help you develop a healthy gut microbiome. Jardine explains, "It's been well established in the literature that plant-based eating patterns increase the gene diversity of the microbiome." You can improve your gut health by including high-fiber whole grains, fruits, vegetables and legumes in your diet. Getting adequate fiber—25 to 38 grams daily, which most of us don't meet—can boost not only your gut function, but also your overall health.
Research on gut health is still budding, but the future is exciting. According to Tine Rask Licht, Ph.D., lead researcher on the new mice study, "When more pieces of the puzzle are in place, we may be able to build on studies like this to design new strategies that can help prevent obesity, diabetes and cardiovascular diseases in humans." In the meantime, following a healthy, plant-based eating pattern—including plenty of prebiotics, probiotics and fiber—while managing stress, exercising and getting adequate sleep, can help your good gut bacteria flourish—and maybe even make it easier to maintain a healthy weight.
Watch: How to Lose Weight with a Diet Meal Plan