Promote human growth hormone production (HGH). Fasting can raise HGH by as much as 1,300 percent in women and 2,000 percent in men.12 HGH plays an important part in health, fitness, and slowing the aging process. It's also a fat-burning hormone Lower triglyceride levels and improve other biomarkers of disease Boost production of brain-derived neurotrophic factor (BDNF), stimulating the release of new brain cells and triggering brain chemicals that protect against changes associated with Alzheimer's and Parkinson's disease. (Alternate-day fasting — restricting your meals on fasting days to about 600 calories — can boost BDNF by 50 to 400 percent, depending on the region of the brain.13