Here’s a startling truth. I can make you fat. Actually, I can make anybody fat. How? I simply prescribe insulin injections. Giving people extra insulin leads inevitably to weight gain. In type 1 diabetes, when insulin levels are extremely low, patients lose weight no matter how many calories they eat. Give insulin — gain weight. No insulin — lose weight (even to the point of death). Because if insulin causes weight gain, then losing weight depends upon lowering insulin.