The 'bacteria' diet

Today there exists about a million and one diets for controlling our weight.

From the well-known Atkins diet (low in carbohydrate) to the Beverley Hills diet (nothing but the odd fruit) and my personal favourite, the Paleolithic diet (based on the eating habits of humans during the Paleolithic era), we are obsessed with our weight. Of course, it is important for us to maintain a healthy weight for many different reasons.

Since obesity is now a fully-fledged global pandemic associated with our poor diets and deskbound existence, there has been increasing interest in what factors make individuals more or less likely to maintain healthy weights. Over the last ten years there has been a great surge in research looking at how bacteria could affect our body weight (see graph).

Graph produced by searching the key terms “Human”, “fat” and “bacteria” in the published literature (Web of Science © 2015 Thomson Reuters).

Along with other microorganisms, such as fungi, viruses and protozoa, there are thousands of species of bacteria that live on and within your body that perform diverse functions. In your intestine, for example, there exist bacteria that: digest nutrients in your diet; provide protection against pathogens that cause infection; and develop your immune system.

These guys are the ‘good’ bacteria in your life.

You need them.

Importantly, research is beginning to find that lean and overweight people differ in the bacterial species that live in their gut. For example, whilst lean individuals have more of one type of bacteria, overweight individuals have more of a different type. Since different types of bacteria interact with people in different ways, such as digesting different things and influencing how people use and store energy differently, it is hypothesised that the community of bacteria you harbour could influence your chances of obesity and diabetes. For example, people who harbour certain bacteria that extract more calories from food than other bacteria will gain more calories from a given diet. As a result, individuals with these bacteria will gain weight at a faster rate than individuals with different bacteria in their gut. Consequently, it is thought that treating individuals with bacterial communities found in lean people could aid in fighting obesity.

So, could altering the community of bacteria in your gut prove the next big diet? Could it be used to prevent and treat obesity? As it stands there exist many unanswered questions, for example:

1) what determines whether you have lean or overweight-associated bacteria?

2) If you alter your bacterial community, will it persist or revert back to its previous state?

3) how much will a lean ‘bacteria diet’ actually aid in preventing and curing obesity in humans?

So far, research suggests that the bacteria you are exposed to (e.g. if you were born via C-section versus natural birth, and breast-fed versus bottle-fed), what you eat (e.g. high fat, low fruit, veg and fibre diet versus low fat, high fruit, veg and fibre diet) and the genes that you inherited from your parents all influence together what bacteria you harbour. These factors are therefore likely to influence the success of bacterial treatment.

As we gain a better understanding of the roles bacteria play in obesity and diabetes we will be better able to predict how their application may contribute to public health. One thing we can be certain of, however, is that ‘bacterial dieting’ is unlikely to be a stand-alone strategy. As with all treatments targeting health, exercise and eating healthily will always be of utmost importance.