Lose weight: The intestinal flora determines the weight

Are intestinal bacteria the real managers in gaining and losing weight?

In recent years, various scientific studies have shown that intestinal bacteria have an influence on weight. Studies have shown, among other things, that these bacteria control our feeling of satiety and can cause obesity. German researchers have now dealt with the question of whether the influence of intestinal bacteria in overweight people may be greater than previously thought.

According to a message, scientists from the Greifswald University Medical Center accompanied a group of diabetics with severe weight problems (obesity) over a period of three months as part of a multimodal structured weight loss program and also recorded the changed intestinal flora during bowel movements.

Positive effect on the composition of the intestinal bacteria

"We were able to show that the initial meal replacement therapy had a positive effect on the composition of the intestinal bacteria and probably also contributed to the good weight loss in addition," explained Prof. Dr. Markus M. Lerch, Director of the Clinic for Internal Medicine A at the University Medical Center Greifswald, who led the investigations with his team and other scientists. The study results were published in the journal "PLOS ONE".

Bacterial composition analyzed in bowel movements

In the first six weeks, the subjects between the ages of 18 and 70 were given only liquid substitute meals in the form of bag food with a maximum of 800 kcal per day. In the following four weeks, this was partially supplemented with healthy food and the final five weeks replaced by a reduced-calorie diet. The study participants lost between 11.4 and 30.1 kg in the period, whereby the decisive values ​​for diabetics such as blood sugar, insulin levels and uric acid improved significantly.

"Using modern sequencing methods, we analyzed the bacterial composition in the stool of the patients before changing their diet, at the end of the six-week fasting phase and at the end of the program," explained Dr. Fabian Frost, the first author of the study.

"After the fasting period, the composition of the intestinal bacteria in all subjects changed significantly. We observed an increase in the diversity of the bacteria and in particular the decrease in the Collinsella bacterial species. Increased levels of Collinsella bacteria are associated with a deterioration in metabolism, an increase in total cholesterol and bad LDL cholesterol, and increased vascular calcification. "

Interestingly, towards the end of the program, most changes in intestinal bacteria almost return to their original level with the self-prepared food, but the amount of Collinsella bacteria remains 8.4 times below the initial level. "For us, this can be a marker for improved health through weight loss," says the gastroenterologist.

Influence of the intestinal flora has not yet been sufficiently researched

In recent years, a major focus in many clinical pictures has been on the composition of the bacteria in the intestine. A connection between the intestinal flora and a wide variety of diseases, for example diabetes mellitus and obesity (obesity), but also depression and Alzheimer's dementia could be found.

Obese people have been shown to have fewer different bacteria in their intestines than leaner contemporaries. In addition, a higher weight gain has been observed in patients with a lower diversity in the bacterial species over a certain period of time.

“The interaction between the bacteria and their control functions has not yet been fully established. However, it must be assumed that certain bacteria ensure that more energy is provided and absorbed into the body from the same food that is taken in than by other bacteria. The composition of the bacteria seems to be a reason why people digest food so differently, why some can increase and decrease quickly, others slowly, ”said senior physician Dr. Antje Steveling, head of the Greifswald Obesity Center.

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

Diversity in the gut

In addition to genetic factors, food plays a crucial role in the composition of the intestinal flora. 38 trillion bacteria live in the intestine and these are decisive whether we stay healthy or get sick. A particularly species-rich gut microbiome, as the group of microorganisms is called, has health-promoting effects and many diseases are associated with a decrease in the biodiversity of the bacteria in the gut.

Around 40,000 different bacteria are known. Since bacteria are much smaller than human body cells, these bacteria only weigh around two kilograms. (ad)

Author and source information

This text corresponds to the requirements of the medical literature, medical guidelines and current studies and has been checked by medical doctors.


  • Universitätsmedizin Greifswald: Are the intestinal bacteria the actual managers in gaining and losing weight ?, (accessed: August 19, 2019), Universitätsmedizin Greifswald
  • PLOS ONE: A structured weight loss program increases gut microbiota phylogenetic diversity and reduces levels of Collinsella in obese type 2 diabetics: A pilot study, (access: 19.08.2019), PLOS ONE

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