What role do intestinal bacteria play in weight gain and weight loss?

Is the influence of intestinal bacteria on overweight people greater than previously assumed? A research team from the University of Greifswald, Germany, monitored a group of people with diabetes and obesity and recorded altered intestinal flora.

Influence of intestinal bacteria on health is under further scrutiny

Is the influence of intestinal bacteria on overweight people greater than previously assumed? A research team from the University of Greifswald, Germany, monitored a group of diabetics with obesity for three months as part of a multimodal, structured weight loss program and recorded the altered intestinal flora in the bowel movement.

In the first six weeks of the study, participants aged 18 to 70 years received exclusively liquid substitute meals with a maximum of 800 kcal per day. In the following four weeks, these were partly supplemented by healthy foods and the final five weeks were replaced by a calorie-reduced diet. Participants had a weight loss in the experimental time period of between 11.4 and 30.1 kgs, with decisive values such as blood sugar, insulin levels, and uric acid greatly improved.

"We were able to show that an initial meal replacement therapy has a positive effect on the composition of the intestinal bacteria and probably also contributes to a substantial weight reduction," emphasised Prof. Dr. Markus M. Lerch, Director of the Clinic for Internal Medicine at the University of Greifswald Medical Center, Germany, who led the investigations with his team and other scientists.

Composition of the intestinal bacteria changed after a fasting period

"Using modern sequencing methods, we analyzed the bacterial composition in a patient’s bowel movements before the diet change, at the end of the six-week fasting phase and at the end of the program," said Dr. Fabian Frost, the main study author. "After the fasting period, the composition of the intestinal bacteria changed significantly in all participants. We were able to observe an increase in bacterial diversity and in particular a decrease in the Collinsella bacteria species. An increased presence of Collinsella bacteria is associated with metabolic deterioration, an increase in total cholesterol and bad Low-density lipoprotein (LDL) cholesterol, as well as increased blood vessels calcification".

Interestingly, towards the end of the program, most of the changes in the intestinal bacteria almost returned to the initial levels, but the amount of Collinsella bacteria remained 8.4 times below the initial level. "For us, this can be a marker for improved health as a result of losing weight," stated the gastroenterologist.

Influence of intestinal flora not yet sufficiently researched

In recent years, a major focus in many clinical analyses has been on the
composition of bacteria in the intestine. Thus a connection could be found between the intestinal flora and various diseases, for example, diabetes mellitus and obesity, but also depression and Alzheimer's dementia. In the meantime, patients with a smaller variety of bacterial species have also experienced a higher weight gain over a certain period of time.

"The interaction between the bacteria and their control functions is not yet fully understood. However, it must be assumed that certain bacteria ensure that more energy is provided and absorbed into the body from the same food than by other bacteria. The composition of the bacteria seems to be one reason why people digest food so differently, why some can increase and decrease quickly and others slowly," said Dr. Antje Steveling, head of the Greifswald Obesity Centre, Germany.

Research into the influence of intestinal bacteria on body weight and health will be further intensified at the University of Greifswald  Hospital. "It is also of interest how an activating and positive composition of the intestinal flora can be maintained after the end of a diet program," emphasized Dr. Frost.

A structured weight loss program increases gut microbiota phylogenetic diversity and reduces levels of Collinsella in obese type 2 diabetics: A pilot study. Fabian Frost, Lena J. Storck, Tim Kacprowski, Simone Gärtner, Malte Rühlemann, Corinna Bang, Andre Franke, Uwe Völker, Ali A. Aghdassi, Antje Steveling, Julia Mayerle, Frank U. Weiss, Georg Homuth, Markus M. Lerch. Published: July 18, 2019, https://doi.org/10.1371/journal.pone.0219489