Weight loss, from a conceptual viewpoint is actually quite simple, but there are so many nuances that make it quite difficult to achieve and maintain an ideal weight. Your body is designed by evolution, with vestiges from long-past times. Your body will do all it can to not allow you to diet down and die because you ran out of energy. To understand how this mechanism works will help you reduce down to a healthy weight.
This is an interesting theory, and a very minority one. The traditional theory is that obesity is caused by a person’s lack of will power, where if you don’t eat you won’t gain weight. This theory, the Carbohydrate-Insulin Model (CIM) of obesity, says that insulin is a hormone. When you eat carbs or sugar, insulin kicks in and tells your cells to burn carbs and not fat. You therefore crave more carbs and accumulate and not burn fat.