“How We Gain and Lose Weight
To understand how we gain and lose weight, we need to start with insulin. Medical researchers and internal medicine doctors almost universally agree that the amount of insulin a person produces determines weight gain and weight loss. For example, Gary Taubes, a medical researcher and recipient of multiple awards from the National Association of Science Writers, refers to insulin as “the stop-and-go light of weight gain and loss.” 
 
Produce more insulin—you will gain weight. Produce less insulin— you will lose weight.”