Gut Health – by Marthinus Opperman – May 16, 2025

The Role of Gut Bacteria in Body Weight

There are more than 1 000 species of bacteria in your gut Scientists are fascinated by how these microbes influence the human body – the impact of these little organisms seems wide-ranging. Scientists think that gut bacteria play a role in the development of Inflammatory Bowel Disease and Irritable Bowl Syndrome. They can also affect your liver and impact inflammation in your body. What’s more fascinating, is that they seem to play a role in mental health (depression and anxiety) and they might contribute to the development of obesity, diabetes and metabolic syndrome. The role that gut bacteria play in weight gain is complex. They affect how certain food is digested and releases chemicals that help you feel full. Certain gut bacteria can also cause inflammation and in turn weight gain. Gut bacteria influence body weight because it affects digestion, inflammation and satiety. Exercise and certain gut bacteria can also act synergistically to help with weight loss. Gut bacteria and digestion Studies suggest that people with obesity have different gut bacteria than those with a normal BMI. This might be because gut bacteria help digest certain foods. The bacteria, Prevotella, for example, helps break down carbohydrates and fibre. The human body can’t digest fibre but when Prevotella digests fibre it releases a number of chemicals. These chemicals can spur on the growth of beneficial bacteria that might help you lose weight. Other gut bacteria digest flavonoids, antioxidants that might help regulate body weight. Gut bacteria and inflammation Some species of bacteria can trigger an immune system response as they cause inflammation. These bacteria produce a chemical called lipopolysaccharide (LPS), which causes inflammation when they pass into the blood. These bacteria can also cause insulin resistance and weight gain. Researchers suggest that the refined carbs in the modern diet may encourage the growth of inflammatory gut bacteria that can increase your risk of obesity and inflammatory bowel disease. There are also gut bacteria that help reduce inflammation and prevent weight gain. Studies have found that the bacteria, Akkermansia can help reduce inflammation and weight gain. Akkermansia helps thicken the intestinal barrier. Your gut is where millions of microbes and environmental antigens get into contact with your immune system and a strong intestinal barrier can protect you from inflammation. Some studies have shown that weaker intestinal barriers are not only a risk factor for inflammation but is also a risk factor for obesity. The research shows that people with obesity have weaker gut linings. Gut bacteria and satiety Hormones control your appetite but it seems that gut bacteria control how much of these hormones are produced. Gut bacteria can also play a role in helping you feel full. The gut bacteria that digest fibre release short-chain fatty acids. These are chemicals and one of these chemicals in particular called propionate, is good for weight loss. Propionate influences the hormones that control your appetite and one study found that participants who took propionate for 24 weeks ate less and lost weight. Gut bacteria and exercise Whether you are running, gardening or playing table tennis, physical activity has numerous health benefits. Research shows that active people have more helpful bacteria in their gut. One study has found that active people have more butyrate, a short-chain fatty acid that can help fight obesity and related illnesses. A lower abundance of butyrate-producing microbes in humans has been associated with an increased risk of metabolic disease. To encourage weight loss, you can spur the growth of helpful gut bacteria. You can do this by eating the right foods and exercising. How to better your gut health to lose weight: The way that gut bacteria influenc satiety, inflammation and digestion is complex. There is no sure-fire way to lose weight, you can’t just take a supplement to enhance the growth of a certain bacteria. Overall gut health will influence weight loss. You can eat foods that nourish good bacteria and stay away from foods that promote the growth of harmful bacteria. Exercise also promotes the growth of healthy bacteria. Change your diet Eating foods high in fibre will spur the growth of beneficial bacteria. Eat whole foods such as fruits, vegetables and whole grains as well as nuts. You can change your gut flora profile in a few days just by eating lots of fibre. You need a variety of bacteria in your gut. Today’s western diet has a severely limited variety of foods to choose from. Only 12 plants and five animal species are used for 75% of the world’s food supply. Eat a variety of fibre-rich foods. Getting 30g of fibre every day from plants of different colours like red peppers, orange pumpkin and purple carrots may also help diversify your microbiota which is good for your overall health. Fermented foods like yogurt, kombucha, kefir and sauerkraut already contain helpful bacteria which can inhibit the growth of harmful bacteria. Eat foods that contain Polyphenol. Polyphenol can’t be digested by the human body but when they are broken down by beneficial bacteria it promotes the growth of helpful bacteria. Foods that contain polyphenol include dark chocolate, green tea and red wine. Taking a probiotic supplement for a while can help restore healthy gut bacteria. Foods with lots of refined carbs, sugar and saturated fat will cause you to gain weight. They also promote the growth of harmful bacteria. To lose weight and keep your gut healthy, it is best to eat less of these foods. Watch out for the effects of antibiotics. Antibiotics, the bacteria killer, not only annihilates harmful bacteria but also kills good bacteria. Usually, antibiotics cause a short-term decline in beneficial gut bacteria but they can also have long-term effects as bacteria do not always grow back to the same amounts after antibiotic treatment. One study found that a single dose of antibiotics reduced the diversity of Bacteroides, one of the most dominant bacterial groups, and increased the number of resistant strains. These effects remained for up to two years. Taking antibiotic medication can lead to weight gain since this medication inhibits and disrupts the growth of gut bacteria. And this is no secret. Industrial agriculture uses low doses of antibiotics to spur on weight gain in livestock. When eating meat, you might also be consuming antibiotics. Eating more plant-based foods can help limit your intake of antibiotics. Do aerobic exercises Exercise can increase the amount of butyrate in your gut and so help you to lose weight. Aerobic exercises, like cycling, swimming, jogging and dancing are especially good for your gut. Takeaway Gut bacteria have big influences on your body and also influenc body weight. How your food is digested, how fast you feel full and how much inflammation you have gets influenced by these little organisms. Exercise seem to also influence your microbiome. Eating lots of fibre-rich foods as well as fermented foods will boost the variety of bacteria that can help you lose some weight. Aerobic exercise also affects your gut health in a positive way. There is no quick and healthy way to lose weight fast but by keeping your gut healthy you can help your body shake off those extra kilograms.