Overweight and obesity are increasing at an alarming rate all over the globe. In the United States, for example, the prevalence of obesity has increased from 30.5% to 42.4% over the past four decades (1).
One of the main reasons behind this obesity epidemic is an imbalance in the composition of the gut microbiota, also known as gut flora. This microbiota is composed of trillions of bacteria that live in our intestines and play a crucial role in our health, from digesting our food to boosting our immunity (2, 3).
Recent studies have shown that the composition of the gut microbiota is different in obese people compared to people of normal weight. In particular, obese people tend to have a higher proportion of Firmicutes bacteria and a lower proportion of Bacteroidetes bacteria (4).
Now, a new study has found that increasing the level of ‘good’ gut bacteria could help people lose weight.
The study, which was published in the journal Nature Medicine, involved feeding a group of mice a high-fat diet for 16 weeks. This diet caused the mice to become obese and to develop a range of obesity-related health problems, such as insulin resistance and inflammation (5).
The researchers then transplanted gut bacteria from the obese mice into a group of ‘germ-free’ mice, which are born without any gut bacteria. The germ-free mice then became obese and developed the same health problems as the mice that had been fed a high-fat diet (5).
The researchers also transplanted gut bacteria from lean mice into the obese mice. This led to a significant reduction in body fat, improved insulin sensitivity, and reduced inflammation (5).
These findings suggest that the gut microbiota plays a significant role in the development of obesity and that ‘good’ gut bacteria could help to protect against it.
The gut microbiota is complex and composed of many different species of bacteria. Therefore, it is likely that different types of bacteria have different effects on weight. The next step is to identify which specific bacteria are responsible for the beneficial effects seen in this study.
In conclusion, this new study provides further evidence that the gut microbiota plays an important role in obesity. Targeting the gut microbiota could be a promising new strategy for the prevention and treatment of obesity.
The microbiome—the collection of trillions of good and bad bacteria that live in our guts—has been linked to everything from immunity to mental health. Now, new research suggests that the microbiome could also play a role in weight loss.
In a new study published in the journal Nature, researchers found that when mice were given a specific type of good bacteria, they not only lost weight, but also showed signs of improved metabolism.
“These results suggest that certain members of the microbiome can promote energy expenditure and help to prevent obesity,” said study author Pamela Silver, a professor of systems biology at Harvard Medical School.
To reach their findings, the team of researchers from Harvard Medical School and the Wyss Institute for Biologically Inspired Engineering fed mice two different types of bacteria: one that was high in a compound called butyrate, and one that was low in butyrate.
Mice that were fed the high-butyrate diet showed increased levels of a protein called FGF21, which is known to play a role in energy expenditure and metabolism. They alsolost weight, even when they were eating the same amount of food as the other mice.
“This is the first time that we’ve seen the microbiome directly influence metabolism in a way that leads to weight loss,” said senior author Wyss core faculty member George Church, who is also a professor of genetics at Harvard Medical School.
To see if the same effects could be achieved in humans, the team also looked at a group of obese people who were undergoing surgery to have their gastric band removed.
They found that the patients who had higher levels of butyrate in their gut also had higher levels of FGF21.
“This suggests that the microbiome could be a potential target for new obesity treatments,” Silver said.
The findings are still preliminary, and more research is needed to confirm the link between the microbiome and weight loss in humans. But the new study provides yet another example of the many ways in which the microbiome affects our health.