Poor Gut Health Might Be the Reason You're Not Losing Weight—Here Are 4 Things You Can Do About It

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 2021 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 six- 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 group that lost weight, including genes that help beneficial 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 was different in obese people than in people who were non-obese, 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 non-obesity are not the same factors that dictate whether you will lose weight on a lifestyle intervention."

4 Ways to Build Better Gut Bacteria

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

Eat More Probiotics

Probiotics like Lactobacillus and Bifidobacterium found in yogurt, kefir, tempeh and more are the "good bugs" that populate your gut.

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.

Take It Easy on Red Meat

Carnitine, a compound found in red meat, may interact with gut bacteria to increase the risk for plaque in the arteries, research suggests. High-protein foods contain carnitine, but red meat has the highest levels. 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.

Limit Low-Nutrient, Highly Processed Foods

It's hard to study "processed foods" as a whole because each food has different ingredients—but the biggest issue with processed foods is that they lack several nutrients, including fiber that feeds gut bacteria, and may be filled with added sugars, salt, artificial sweeteners and/or additives and preservatives. Your microbiome thrives on a diversity of dietary fibers and polyphenols from a variety of colorful fruits, vegetables, whole grains and other fresh and lightly processed plant foods. That's not to say that you have to avoid all processed foods—there are plenty of healthy options that make eating healthy easier (think: canned tomatoes, whole-wheat bread and pasta, and even things like frozen veggie burgers). Being choosy can help weed out the less-than-healthy options.