Extensive and very interesting review over adaptations of human physiology to overfeeding. 78 pdf pages may look quite too many for some of you, but they embrace virtually every study in this field form the beginnings of 20th century. If you haven't got enough time to read it all, you can go to the final discussion where they comment on the most important aspects:
Gais in body mass has a strong correlation to energy excess, specially during the first phase.
Individual variability in weight gain coud be up to 3-fold.
Weigh gain is about 60% of excess calories in long-term overfeeding.
Gain in lean body mass is about 30-40% of total, but it is highly dependent on protein intake: virtually no lean mass gain if dietary proteins are very low.
Contributions of age, gender and ethnicity on weight gain are not well studied.
Mayor predictors of weight gain in overfeeding are:
- low fat‐free mass
- low skeletal oxidative potential
- low cardiorespiratory fitness
- low plasma androgen levels
- high plasma leptin levels.
Determinants of rise in resting metabolic rate are unclear. It seems that brown fat, sympathetic system and uncoupling protein have no major role in humans.
The rise of thermic effect of food after overfeeding has not been accurately studied. today it cannot be regarded a mayor component of energy dissipation.
Energy expenditure associated to physical activity in overfeeding has not been easy to investigate and is an area of further research.
The biological basis of variability in energy dissipation are unclear: miticondrial proton leakage and futile cycles (more than 100.000 in mammalian cells) are candidates that warrant further research.
Carbohydrate and fat oxidation increases and decreases respectively. Protein metabolism is less clear.
Endocrine changes are extensively known: GH decreases, adrenal activity increases. T3 rises. Insulin deficiency increases, and gut hormones, contrary to expected, do not change.
Genome‐ and transcriptome‐wide technologies could help us understand the genetic components in variability to overfeeding response, but today no clear data are available, as well as in DNA methylation.
I hope you found it interesting, if you want to dig deeper https://onlinelibrary.wiley.com/journal/1467789x
