Steven Guyenet has started an impressive series on the genetics of obesity. (Things like this are why I’m so grateful that I live in the age of the Internet! It is so wonderful to have access to the best minds on any topic.)
Part I: http://wholehealthsource.blogspot.com/2013/06/the-genetics-of-obesity-part-i.html
In other words, nearly every major aspect of food behavior is strongly impacted by genes*. Other papers from the same study showed that genes have a strong influence on the amount of food it takes to feel full, how likely it is that the sensation of fullness will terminate a meal, the perception of palatability, how much influence palatability has on calorie intake, cognitive dietary restraint, and almost every other measurable characteristic.
Part II: http://wholehealthsource.blogspot.com/2013/07/the-genetics-of-obesity-part-ii.html#more
A good review of the work done on identifying the elements that influence the genetics of obesity. Lots on Leptin studies:
He concludes with:
The genetic data converge powerfully with other fields such as neurobiology, endocrinology, and physiology, together demonstrating conclusively that:
The brain is the main regulator of body fatness.
The brain regulates body fatness in response to internal signals of energy stores, particularly leptin.
Genetic variability in body fatness is likely predominantly determined by genetic differences in brain function, particularly the hypothalamus.
See also the comment by one of the readers of the blog (Ness Clark) saying that:
My daughter is 2 years old and seemingly has unlimited appetite. At 7 weeks old she was almost at the 100th percentile for weight on breast milk. By 6 months old she was well off the charts. I read an article about the MC4R mutation and have wondered since if she has inherited it – her nana on her dads side has been obese since late childhood but also has low blood pressure which apparently fits with this.
It really puts the lie to the idea that if we only were perfectly natural in our habits that no one would be obese. Clearly if an infant can be at the 100th percentile in weight eating only breast milk, there is something going on other than will or natural food sources. I am looking forward to his next piece on why genetics is not necessarily destiny.