Certain bacteria including Lactobacillus and Bifidobacterium, are believed to have properties which keep us healthy (anti-inflammatory, anti-tumorigenic, and pathogen exclusion properties).
Having antibiotics, medication, alcohol, a lot of sugary foods, smoking and stress can all alter the balance of bacteria in the gut, which can then increase the risk of disease directly or indirectly.

Research is now showing that these beneficial bacteria can also have an effect on the way we store fat, how we balance levels of glucose in the blood, and how we respond to hormones that make us feel hungry or full.

Studies on twins who were either both obese or lean showed that those who were lean had a much bigger variety of gut bacteria. Bacteria were then transferred into mice, those that received bacteria from the obese twins became obese themselves, whilst those receiving bacteria from the lean twins, remained lean. When they moved all the mice into the same cage, the obese ones started to lose weight as they picked up more of the “lean type” bacteria!

Next, studies demonstrated the complex interaction among food, microbes and body weight by feeding the mice specially prepared unhealthy food that was high in fat and low in fruits, vegetables and fibre. With this “Western diet,” the mice with obese-type microbes proceeded to grow fat even when housed with lean mice. The unhealthy diet somehow prevented the good bacteria from moving in and flourishing.
So to lose weight, it looks like we need the right bacteria in our gut as well as the right food.