These 2015 Michigan/Argentinian fish and rodent studies were of the genetic programming of specific neurons in the hypothalamus part of the limbic system. The study linked below found:
“Food intake and body weight regulation depend on proper expression of the..gene..” in these neurons.
In a second study released at the same time from the same researchers:
“The researchers found that the two enhancers act in ways that complement one another, both encouraging the expression of the Pomc gene at key times. One of the two is found in the same form among all mammals, the other among all placental mammals – suggesting that they’ve been kept intact throughout the evolutionary process.”
Genetic programming of these neurons begins during early brain development. One of the researchers said:
“This work represents the first example of a neuron-specific gene in vertebrates where we have found both the enhancers and a shared transcription factor that control gene expression in the developing brain and then throughout the life span of the adult.”
The first study showed that if the genetic expression of these hypothalamic neurons was disrupted, the individual lost control of their eating (hyperphagia) and the usual result was severe obesity:
“We don’t know, but we think it likely, that it [regulation of these specific hypothalamic neurons in humans] may be similar to the mouse model, where its role is like a dial, with a linear relationship between the amount of Pomc [the gene] expression and the degree of obesity.”
I hope that when extending this research to humans, the researchers don’t exclude emotional content like most studies involving areas of the limbic system have done. Everyone has feelings intermixed with eating and foods. It’s a great disservice, in my opinion, to have publicly funded studies not include aspects of emotion that could potentially help people.
http://www.pnas.org/content/112/15/E1861.full “Islet 1 specifies the identity of hypothalamic melanocortin neurons and is critical for normal food intake and adiposity in adulthood”