Skip to main content

A recent study of the probiotic strain L. rhamnosus revealed that women taking the supplement lost twice as much weight as those who consumed a placebo. This exciting news was published in the British Journal of Nutrition by a team of researchers headed by Université Laval Professor Angelo Tremblay.


Some studies have previously shown that the bacteria in the GI tract of obese people is generally different than the strain makeup of thin folks. One of the main reasons may be that people who are obese tend to consume foods that are high in fat and low in fiber. Those type of foods promote the growth of certain types of bacteria at the expense of others.


The head of the recent study, Professor Tremblay, along with his team attempted to determine if consuming specific strains of probiotics could help reestablish the balance of bacteria in individuals so as to promote a condition where a healthy weight is induced. To test their hypothesis, researchers recruited 125 overweight men and women. The subjects underwent a 12-week weight-loss diet, followed by a 12-week period aimed at maintaining body weight. Throughout the entire study, half the participants swallowed 2 pills daily containing probiotics from the Lactobacillus rhamnosus family, while the other half received a placebo. After the 12-week diet period, researchers observed an average weight loss of 4.4 kg in women in the probiotic group and 2.6 kg in the placebo group. However, no differences in weight loss were observed among males in the two groups. “We don’t know why the probiotics didn’t have any effect on men. It may be a question of dosage, or the study period may have been too short,” says Professor Tremblay, who is also the Canada Research Chair in Environment and Energy Balance.


After the 12-week maintenance period, the weight of the women in the placebo group had remained stable but the probiotic group had continued to lose weight, for a total of 5.2 kg per person. In short, women consuming probiotics lost twice as much weight over the 24-week period of the study. Researchers also noted a drop in the appetite-regulating hormone leptin in this group, as well as a lower overall concentration of the intestinal bacteria related to obesity. According to Angelo Tremblay, probiotics may act by altering the permeability of the intestinal wall. By keeping certain proinflammatory molecules from entering the bloodstream, they might help preventing the chain reaction that leads to glucose intolerance, type 2 diabetes, and obesity.


This recent study mainly focused on only one strain of Lactobacillus rhamnosus, but Professor Tremblay believes that other probiotics found in dairy products could have a similar effect. He stresses, however, that the benefits of these bacteria are more likely to be observed in a favorable nutritional context that promotes low fat and adequate fiber intake. As prominent researches continue to discover more possible beneficial effects of probiotic supplementation, we can surely expect probiotic supplement awareness to increase.