Overfeeding Changes Gut Bacteria Which Become 'better' At Harvesting Energy...
How's this one for your gut bacteria giving you the finger...
There are a few studies & articles on this topic, a google of something like 'firmicutes bacteroidetes energy harvest' gives you a good selection.
one article reads; "It has been shown that the higher your energy intake is above that required to maintain your weight, the greater the increase in Firmicutes and the decrease in Bacteroidetes in your gut flora. This results in more calories being extracted from the food you consume rather than lost in your stools, making it harder to lose or maintain your weight."
From a 2001 study:
"Results: The alteration of the nutrient load induced rapid changes in the gut microbiota. These changes were directly correlated with stool energy loss in lean individuals such that a 20% increase in Firmicutes and a corresponding decrease in Bacteroidetes were associated with an increased energy harvest of ~150 kcal. A high degree of overfeeding in lean individuals was accompanied by a greater fractional decrease in stool energy loss."
If you didn't quite grasp that quote; it is basically saying that if you overeat (overfeed), your gut bacteria will alter (more firmicutes, less bacteroidetes) and get more efficient at extracting energy (calories) from the food you eat, to the extent of harvesting/extracting an extra ~150 cals per day from your meals.
(in some ways, you would have thought it should have been the other way round...eat less, and the gut bacteria become more efficient extracting calories. but life aint always fair).
fake it till you make it