Visiting this forum from time to time, it appears that "leptin" is the cornerstone of primal, or else it's got something to do with sex! How else to explain the volume of input?
What the heck is leptin?
Leptin decreases appetite, increases metabolism and is released proportionally to adipose tissue. It’s the most important negative feedback hormone for body fat homeostasis. Obese people have a lot of leptin, but are leptin resistant, a condition where their hypothalamus doesn’t register all the leptin. Leptin resistance is characterised by an increased appetite and decreased metabolism. Body fat then increases to the point where the leptin released by adipose tissue is at equilibrium with the level of leptin resistance. Leptin and leptin resistance are the foundation of the setpoint theory of obesity, which was proposed long before leptin was discovered.
Whole Health Source: The Body Fat Setpoint
Whole Health Source: The Body Fat Setpoint, Part III: Dietary Causes of Obesity
Whole Health Source: The Body Fat Setpoint, Part IV: Changing the Setpoint