Gut bacteria could hold key in obesity fight

The findings – presented as part of the scientific program of the American Society for Nutrition (ASN) – reveal that altering the make-up of the intestinal microbiota in rats can lead to changes in dietary habits.

Speaking at the ASN, the researchers – led by Dr Mihai Covasa from the French National Institute for Agricultural Research (INRA) – noted that obese people tend to have gut microbe profiles than lean individuals. They suggested that some bacteria commonly found in obese individuals could metabolise food differently – in a way that allows the individuals to harvest more energy, and deposit this energy as fat.

 “After eight weeks of high-fat feeding, we found that obesity-prone germ-free animals gained more weight, and had increased adiposity and 2 hour food intake compared to obesity-resistant germ-free,” explained the researchers.

“These results demonstrate the ability of the gut microbiota to modulate host metabolism, by altering both intestinal nutrient sensing and energy-storing signalling pathway information, and ultimately contributing to the obese state,”they suggested.

To determine whether altering the bacterial profile of an individual really could alter obesity risk, Covasa and his colleagues at INRA transferred the intestinal bacteria of obesity-prone or obesity-resistant rats into the guts of germ-free mice with no innate gut microbiota.

The researchers then fed some animals a ‘regular’ diet, while others were given unlimited access to a high-fat diet. They said food intake and weight gain were then monitored for eight weeks, before intestinal samples were analysed for a variety of physiologic markers of metabolism and normal feedback mechanisms known to play a role in maintenance of energy balance.

Covasa revealed that mice receiving intestinal bacteria from obesity-prone animals ate more food, gained more weight, and became more obese than those receiving microbiota from obesity-resistant animals.

Animals with microbiota transferred from obesity-prone rats were also found to exhibit changes in intestinal nutrient sensors and gut peptide levels – something Covasa suggested would likely influence how the animals respond to eating.

The research team said their findings could have important implications.

Firstly, the team said the findings have lead them to theorise that obese individuals, when given the opportunity to overeat, may harbour specific gut microbiota profiles that promote excess weight gain. Secondly, they suggested that such differences in gut microbes could be related to behavioural changes and increased food intake.

Covasa and his team also said they believe that the microbiota profile an individual has may influence the ability to properly sense and respond to a meal.

They hope the results of the new study will eventually lead to the discovery of new ways to fight obesity via the manipulation of intestinal microbiota profiles.