Gut Bacteria May Affect Body Weight Regulation
There are hundreds of different microorganisms in your digestive system. The majority of these are bacteria, most of which are friendly. Friendly bacteria produce several important nutrients, including vitamin K and certain B-vitamins. They also help break down fiber that the body can’t digest, turning it into beneficial short-chain fatty acids like butyrate.
Both human and animal studies have found that normal-weight people have different gut bacteria than overweight or obese people. In those studies, people with obesity had more firmicutes and fewer bacteroidetes, compared to normal-weight people. There are also some animal studies showing that when the gut bacteria from obese mice are transplanted into guts of lean mice, the lean mice get fat.
All of these studies suggest that gut bacteria may play a powerful role in weight regulation.
How Can Probiotics Affect Changes in Weight?
It is thought that certain probiotics may inhibit the absorption of dietary fat, increasing the amount of fat excreted with feces. In other words, they make you “harvest” fewer calories from the foods in your diet. Certain bacteria, such as those from the Lactobacillus family, have been found to function in this way.
Probiotics may also fight obesity in other ways:
- Release of GLP-1: Probiotics may help release the satiety (appetite-reducing) hormone GLP-1. Increased levels of this hormone may help you burn calories and fat
- Increase of ANGPTL4: Probiotics may increase levels of the protein ANGPTL4. This may lead to decreased fat storage.
BOTTOM LINE: Probiotics may reduce the number of calories you absorb from food. They also affect hormones and proteins related to appetite and fat storage. They may also reduce inflammation, which can drive obesity.
Probiotics May Help You Lose Weight and Belly Fat
Studies have found that certain strains of the Lactobacillus family can help you lose weight and belly fat. In one study, eating yogurt with Lactobacillus fermentum or Lactobacillus amylovorus reduced body fat by 3–4% over a 6-week period. Another study of 125 overweight dieters investigated the effects of Lactobacillus rhamnosus supplements on weight loss and weight maintenance. During a 3-month study period, the women taking the probiotics lost 50% more weight compared to the group taking a dummy pill (placebo). They also continued to lose weight during the weight maintenance phase of the study.
Lactobacillus Gasseri
Of all the probiotic bacteria studied to date, Lactobacillus gasseri shows the most promising effects on weight loss. Numerous studies in rodents have found that it has anti-obesity effects. Additionally, studies in Japanese adults have shown impressive results. What’s more, belly fat was reduced by 8.5%. However, when participants stopped taking the probiotic, they gained back all of the belly fat within a month.
One study followed 210 people with a lot of belly fat. It found that taking Lactobacillus gasseri for 12 weeks reduced body weight, fat around organs, BMI, waist size and hip circumference.




