A range of studies have shown that the microbiota of obese individuals is quite different to that of people with no weight problems. Now, a study led by researchers from the Université Laval in Canada and Nestlé, has taken things further by showing that, with the help of probiotics, the balance of the gut microbiota may be changed in order to increase the number of digestive bacteria that encourage healthy weight.
Professor Angelo Tremblay and his colleagues worked with 125 overweight men and women on a weight-loss diet. In addition to this diet, half the sample was given two daily pills containing probiotics from the Lactobacillus rhamnosus family, while the others consumed a placebo. The results showed that over 12 weeks, the women in the group that had taken the probiotics had lost 4.4kg with the diet, while the group that only followed the weight-loss plan lost 2.6kg. Furthermore, in the following months, the women who had consumed the probiotics continued to lose some weight while those who had taken the placebo either stabilised or gained weight. 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.
And what about the male participants? “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. The results of this study were published in the British Journal of Nutrition.
Giovana Martucelli is a nutritionist with a specialization in Clinical and Hospital Nutrition and practical training in Nutritional Therapy. She is currently a Master’s student in Gastroenterology at the Faculty of Medicine of the University of São Paulo (FMUSP), where she works as a researcher at the Laboratory of Nutrition and Metabolic Surgery of the Digestive System (METANUTRI/LIM-35).
With over seven years of research experience, she has built a strong background in the field of gut microbiota, with a particular focus on precision medicine. She is the author of several works presented at national and international conferences and has received awards such as the Best of ASPEN – GI Topics (2025) and the Research Travel Award (ESPEN, 2024).
Mónica Quinzo holds a BSc in Biochemistry and an MSc in Immunology Research, backed by years of hands-on biomedical research in vaccinology for neglected tropical diseases affecting gut health. Driven by her core purpose of “catalysing the impact of science in society through communication,” she has specialized in Medical Copywriting and Healthcare Communications. Mónica is deeply passionate about the gut microbiome's role in immunomodulation, health 360, and longevity. Leveraging her MSc in Science Communication, she crafts high-quality, evidence-based content that bridges the gap between complex biomedical data and society, empowering people to make informed, healthier life choices. Connect with Mónica on 
Konstantina Zafeiropoulou is a dietitian with strong scientific interest in the diet-microbiota interactions and their role in human health and disease. She holds a Master of Science in Human Nutrition from the University of Glasgow, during which she explored the involvement of gut microbiota in the etiopathogenesis of Celiac Disease and evaluated the gluten free diet-microbiota interactions. She is currently a PhD candidate at Amsterdam UMC unraveling the role of gut microbiota and long-term dietary patterns in the development of postoperative colorectal anastomotic leakage. Follow Konstantina on Twitter 