The gut microbiome consists of various bacteria, fungi, and other microorganisms that reside in the digestive tract, with its composition varying among individuals. This microbiome holds the key to understanding our health. In the last 10 years there have been more and more studies done to count and characterize these bacteria. Over 1000 different strains have been identified and each has their own genetic make-up. It can be said that there are 250-800 times more bacterial genes than human genes. Even more remarkable, these bacterial genes make substances that get into the human bloodstream, affecting our body chemistry, metabolism and energy production.
How could they affect our weight? When we eat food, our gut breaks it down into small pieces. Only the smallest pieces get absorbed into our blood. The rest is eliminated as waste material. In other words, not all of the calories in the food we eat get into our body and increase our weight. The gut bacteria help break down food. Some bacteria are better able at breaking down complex carbohydrates (ie: grains and legumes) into simple sugars, which makes them less likely to be stored as fat. Theoretically, if our gut has more of those kinds of bacteria, it should be easier to lose weight.
When it comes specifically to weight, we can look at two specific species: Firmicutes and Bacteroidetes. Obese subjects tend to have a greater amount of Firmicutes species, and a higher Firmicutes to Bacteroidetes ratio than individuals of normal weight. Firmicutes have been shown to be negatively proportional to resting energy expenditure, whereas Bacteroides have been shown to be positively correlated with the percentage of body fat.
We’ve seen evidence of this in rat studies. The microbiome of an obese mouse was transferred into another mouse with no microbiome and it became obese. The same thing was observed when using a lean mouse.
Many factors can alter our microbiome composition and impact the diversity of bacterial strains. These include diet, exercise, medications, supplementation. Any imbalance is known as dysbiosis and is associated with weight gain and obesity. The influence of the intestinal microbiome on metabolism, hormone balance, neurotransmitter function, and the brain can play a major role in weight management and treatment of obesity. Moreover, the use of probiotics and prebiotics improves gut bacterial composition, and has achieved promising outcomes for prevention and treatment of obesity.
A stool test can be taken to determine your specific microbiome makeup, including the above mentioned Firmicutes and Bacteroides. It can also analyze other markers of guy dysfunction like inflammation, infection and metabolic activity. These take-home kits can be picked up at the office.