Feed your gut bugs and you might see a shift on the scale!

When it comes to weight loss, it's important to trust your gut.

By that, we mean eating when you feel hungry and stopping when you feel full—a mindful approach to eating that doesn't include restricting foods (think: the keto diet) or the times you eat during the day (think: intermittent fasting). And we also now know that it's crucial to trust—and support—your gut bacteria. The good bugs in our gut have a direct impact on our ability to lose weight, according to a new study published in the American Society for Microbiology (ASM)'s journal mSystems.

"Your gut microbiome can help or cause resistance to weight loss and this opens up the possibility to try to alter the gut microbiome to impact weight loss," lead study author Christian Diener, Ph.D., a research scientist at the Institute for Systems Biology in Seattle, Washington, tells the ASM.

To determine this, the scientists analyzed a selection of people enrolled in a diet or exercise intervention program that included dietitian- and nurse-lead behavioral coaching. During the 6- to 12-month program, 48 participants lost more than 1% of their body weight per month, and 57 individuals maintained the same body mass index (BMI) and weight. Using metagenomics (AKA analyzing stool and blood samples) and controlling for age, sex and starting BMI, the researchers compared the following factors for the weight-loss and steady-weight groups:

  • Blood metabolites
  • Blood proteins
  • Clinical labs
  • Dietary questionnaires
  • Gut bacteria

A few common factors were found among those in the weight loss cohort, including genes that help bacteria grow at a more rapid rate, multiply more frequently, replicate and assemble cell walls.

"Before this study, we knew the composition of bacteria in the gut were different in obese people than in people who were nonobese, but now we have seen that there are a different set of genes that are encoded in the bacteria in our gut that also responds to weight loss interventions," adds Dr. Diener. "The gut microbiome is a major player in modulating whether a weight loss intervention will have success or not. The factors that dictate obesity versus nonobesity are not the same factors that dictate whether you will lose weight on a lifestyle intervention."

A woman's mid section with a cut out exposing flowers in the shape of intestines
Credit: Getty Images / ondacaracola photography / Hiroshi Watanabe

5 Ways to Build Better Gut Bacteria

Whether you're born with these gut-healthy genes or not, you can drastically adjust (and improve) the health and strength of your gut bacteria.

  1. Eat more probiotics. Probiotics like Lactobacillus and Bifidobacterium found in yogurt, kefir, tempeh and more are the "good bugs" that actually make up your microbiome. (Try these 7 must-eat fermented foods for a healthy gut.)
  2. Then keep 'em strong with prebiotics. Just like any other living thing, this bacteria needs food to survive and thrive. Prebiotics are the fibers that do just that—act as fuel to feed the probiotics in your gut. Add apricots, artichokes, almonds, pistachios and legumes, plus polyphenol-rich foods like blueberries, strawberries and apples for a good dose of prebiotics.
  3. Fill up on fermented foods. These funky items are full of probiotics. Here are 7 EatingWell dietitian faves!
  4. Take it easy on red meat. Carnitine, a compound found in red meat, may interact with gut bacteria to increase risk for plaque in the arteries, research suggests. Opt for fatty fish, chicken, turkey or plant-based proteins instead on most occasions, and if you do eat red meat, aim to do so in moderation.
  5. Limit processed foods. It's hard to study "processed foods" as a whole because each food has different ingredients—but the biggest issue with processed and refined foods is that they lack diversity and fiber and are often filled with added sugars, salt, artificial sweeteners and/or additives and preservatives. Your microbiome thrives on diverse fibers and polyphenols from a variety of colorful fruits, vegetables and whole grains. That's not to say that you have to avoid all processed foods—there are plenty of healthy options out there that make eating healthy easier (think: canned tomatoes, whole-wheat bread and pastas and even things like frozen veggie burgers). Being choosy can help weed out the less-than-healthy options.

Before your next supermarket run, check out 12 Fiber-Rich Foods to Help with Good Gut Bacteria. Craving a complete guide? Our 7-day healthy gut meal plan can help get you started.