Recent research has demonstrated that the microbiome in your gut—made up of bacteria and yeasts—has a surprising amount of influence on your health. Your immunity, your digestion and even your mood can be altered by imbalances in gut bacteria.

Because gut flora can influence so many aspects of your health, it’s natural to wonder whether your microbiome might play a role in weight gain or weight loss. As it turns out, gut health and weight are linked in multiple ways.

Gut flora indirectly affects weight

Inside your gut lives a delicately balanced ecosystem composed of thousands of different microorganism strains. Probiotics, or beneficial bacteria that play essential roles in optimizing health, are necessary parts of this microbiome.

When this ecosystem is balanced, the bacteria and yeast work together to provide health benefits. Some microorganisms feed off the food you eat to create by-products. These might be used by the body or feed other microorganisms that make necessary vitamins and enzymes.

Unfortunately, if this microbiome becomes imbalanced, the health benefits might be swapped for health problems. Imbalances can occur when you don’t have enough of a particular bacterium, when one or two bacteria grow too abundant or when you don’t have enough different types of microorganisms to promote healthy diversity. In other words, previously helpful bacteria might cause problems and throw your intestinal systems out of whack. Most often, imbalances are a result of unhealthy diets that feed harmful bacteria or of antibiotic use, which wipes out both good and bad bacteria.

The ways that bacteria in your gut influence weight are complex. Their effects are largely indirect, rather than direct—operating like a series of dominos. For example, beneficial bacteria help to strengthen the lining of your intestinal walls, while harmful bacteria weaken this lining. Having a weak intestinal lining can worsen inflammation throughout the body, which has been linked to weight gain and obesity.

One way researchers know that intestinal flora play a role in weight regulation is because of the distinct differences found in the microbiomes of overweight individuals compared to those of lean individuals. The two groups have been found to have different bacterial compositions, especially when it comes to diversity of bacteria. Obese people tend to have much lower bacterial diversity.

Although research is still developing, it’s believed that gut bacteria play many indirect roles in determining weight. Most importantly, they aid in regulating digestion, fat storage and hunger. Having the right bacteria operating efficiently can keep these things in check and help you keep weight off, but having an imbalanced microbiome can skew these areas of your health, exacerbating weight gain and potentially making it more difficult to lose weight.

Bacteria and weight are complexly linked

Right now, there are a few specific ways experts believe gut health impacts weight regulation in humans.

There are thousands of bacterial strains that make up your gut’s microbiome, and research is only beginning to highlight the importance of each one. Experts have identified a few particular bacteria that have been linked to lean body weight—particularly Akkermansia muciniphila and Christensenella minuta. However, these bacteria are not for weight loss, per se—meaning, you can’t take a probiotic supplement rich with these strains and expect to shed weight immediately. Instead, research indicates that these bacteria contribute to processes that prevent excessive weight gain, such as the regulation of blood sugar and body fat storage. In obese individuals, the numbers of these bacteria are far lower than they are in lean people.

It’s likely that you have these two strains of bacteria in your gut already, although each of our microbiomes differ based on our genetic makeup. However, those bacteria must be fueled properly through your diet to ensure they flourish and can perform their bodily roles effectively.

Another way experts believe gut bacteria contribute to weight regulation is through by-products. Certain bacteria in your gut break down food particles and convert them into by-products like short-chain fatty acids and vitamins, which are used by the body for a wide range of processes. When it comes to weight regulation, short-chain fatty acids are particularly important.

Some acids, like butyrate or acetate, influence weight-determining bodily systems by sending messages to your brain. One of these systems is the production of hormones that make you feel hungry or full. If you lack enough butyrate-producing bacteria, you might have less of this “full-feeling” hormone, causing you to eat more than you need to. Ultimately, this excess consumption results in higher body fat.

Finally, it’s believed that gut dysbiosis and an overgrowth of certain bacteria might also lead to greater energy extraction from food. This can result in higher blood sugar levels, which leads your body to store more fat.

Promoting a healthy gut for a healthy weight

Unfortunately, there is no quick fix when it comes to an imbalanced gut microbiome and weight regulation. It’s definitely not as simple as taking a probiotic supplement with all the “right” strains to immediately shed weight. However, there are a few things you can do to help regulate your intestinal bacteria and right-size your health for the long term.

Some of these include cutting out sugars and processed foods, exercising (which encourages bacterial balance) and taking probiotic supplements. Additionally, changing your diet to include more whole foods—particularly fruits and vegetables rich in prebiotic fiber—can help bolster the army of good bacteria in your gut and reduce the effects of the harmful microorganisms. This can promote balance between bacteria and help the bacteria that influence weight operate more efficiently.

Much like how the relationships between your intestinal bacteria are symbiotic, so is the relationship between healthy living and a healthy gut microbiome. Eating whole foods and exercising help strengthen and balance the beneficial bacteria in your gut. When your intestinal flora are balanced and healthy, they are able to take those healthy foods and put them to good use, reducing inflammation, strengthening your gut lining and ensuring a well-regulated appetite to help you maintain a healthy weight.