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The Hard To Define Relationship Between Probiotics and Weight Loss

As of 2021, no definitive research supported the claim that probiotics directly help with weight loss. However, several studies indicate that specific strains of bacteria may help reduce calorie absorption and affect hormone and protein production related to fat storage and appetite. Therefore, while eating probiotic-rich foods or supplements may not contribute to weight loss directly, it may alter biological processes responsible for drastic weight gain.

Conflicting Studies and Data

According to a review of several respected studies, probiotics may help you lose weight and belly fat. The reviewed studies showed that bacterial strains in the Lactobacillus family helped participants the most with weight loss.

One study of 125 overweight dieters showed women taking a probiotic containing Lactobacillus rhamnosus lost 50% more weight over three months than those taking a placebo. The women also continued to lose during the weight maintenance portion of the study.

Another study of 114 obese adults provided participants with either a placebo or the probiotic Lactobacillus sakei for 12 weeks. The participants taking the probiotic lost more weight than those on the placebo.

Despite the promising data, not all researchers are convinced probiotics are the definitive cause of weight loss. All professionals concede that the microbiome in leaner individuals contains different microbes than in overweight or obese individuals. However, the difference in the bacteria does not indicate a causal relationship, meaning the studies do not imply whether changing your microbiome causes you to lose weight or losing weight causes a change to your microbiome.

A 2017 study in Nutrition Today found that Bacteroidetes — a bacteria associated with leaner individuals — increased in obese individuals when they took part in a weight loss diet. However, participants in a weight gain study experienced a 20% drop in Bacteroidetes and a 20% increase in Firmicutes — a bacteria associated with obesity.

The Supplement Fallacy

Probiotic supplements are currently flooding store shelves. While some supplements carry strains from the Lactobacillus family, others do not. Even if supplements carry the most researched probiotic strains, researchers are not yet convinced that a supplement delivery system is effective. Some researchers speculate that most bacteria in probiotic supplements cannot survive in the gut.

Healthy Diet Is the Key

The better option to dietary supplements is to focus on probiotic-rich foods and a healthy diet. All researchers can agree that fermented foods contain many health benefits, including improved gut health and weight loss. Some of the most beneficial foods include:

  • Yogurt

  • Kefir

  • Kimchi

  • Miso

  • Sauerkraut

  • Kombucha

  • Tempeh

  • Natto

When you eat a healthy and balanced diet, your microbiome shifts, promoting the growth of bacteria that contribute to fat loss. Adding probiotic-rich foods to your diet may also contribute to gut health.

As the research stands, there is no way of knowing whether probiotics contribute to weight loss or result from it. Current studies suggest a minor causal link, but more research is necessary for any definitive conclusion. Until then, the tried-and-true weight loss advice stands: eat healthier and get more active. Diet remains the most influential component of weight loss or weight gain


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