The underlying theory of blood type diets is that people with different blood types digest lectins differently, and that if people eat food that is not compatible with their blood type, they will experience many health problems.
Leptin is a potent stimulator of the immune system. Leptin receptors on monocytes cause the release intracellularly of STAT3 which cause the monocytes to release IL-6, IL-12 and TNF alpha. The IL-6 goes to the liver and increases production of CRP.
And the Answer: Hey Bernard, Any kind of food stimulates production of leptin. You take in food, the food is digested, and the nutrients from the digested food go to fat cells. Once the fat cells have taken in the nutrients, they release leptin.