Why are some people skinny, even though they eat large
amounts of food, while others become fat? Jeffery Gordon of
Washington University in St. Louis thinks it's because some
people have types of bacteria that cause them to absorb more
calories from their food.
You have two absorption systems in your body. You
absorb most of your food as it passes through your small
intestines. Food that is not absorbed in the small intestine goes
to your colon. The colon contains a huge colony of bacteria that
work to ferment undigested carbohydrates such as soluble fiber
into short chain fatty acids and simple sugars that can then be
absorbed through the colon walls into the bloodstream. Most
people get about ten percent of their total calories from food
absorbed through their colons.
Animal studies lead us to the next step. The dominant
bacteria in the gut of obese mice are Firmicutes, types of bacteria
that have more genes for breaking down the complex starches
and fiber. Mice who are thin have more Bacteroidetes in their
guts, and these bacteria are not as efficient in breaking down fiber
and complex carbohydrates. Transplanting Firmicutes bacteria
into the guts of lean mice made them fat.
These researchers also found that fat humans had far
more Firmicutes bacteria than thinner ones. They then asked
their overweight subjects to go on a low-fat, low-refined-
carbohydrate diet for one year. As they lost weight, their bacteria
changed to predominantly Bacteroidetes.
Today you may be able to lose weight by changing the
composition of your diet in a way that changes the bacteria in your
gut so you absorb fewer calories. In the future, you may be able to
get a pill that contain primarily Bacteroidetes bacteria, take it
daily and watch the pounds melt off because of the change in
intestinal bacteria. from Mirkin newsletter