Years of yo - yo diets, full of refined carbs and chemicals (
hello diet coke, lean cuisines, bagels, cereal, beer, and crackers), eventually cause metabolic damage, usually in the form of Insulin Resistance, and organs that become damaged / worn out (the liver, the pancreas, etc); and our hormonal system shifts from one that's full of Growth Hormone, sex hormones, and fat burning hormones like Glucagon, to a hormonal system full of Insulin and Cortisol.