> Our digestive systems do not extract 10% of available energy from all consumed food, and the amount we do extract varies based on a number of different factor

> Our digestive systems do not extract 10% of available energy from all consumed food, and the amount we do extract varies based on a number of different factors including microbiome, expression of certain hormones (e.g. insulin), etc. Do you have a citation for this? Here's one saying almost the opposite: > Carbohydrates, protein, fats, and alcohol—the dietary macrocomponents—are the sources of energy in the diet. Under normal circumstances, more than 95% of this food energy is digested and absorbed from the gastrointestinal tract to provide the body's energy needs. Studies of normal and overweight subjects have not shown any significant differences in the proportion of food energy absorbed. In some underweight subjects, however, malabsorption of nutrients is an important factor. https://www.ncbi.nlm.nih.gov/books/NBK218769/ https://www.ncbi.nlm.nih.gov/books/NBK218769/