You see, each pound of fat is 3,500 calories. You can lose one to two pounds of fat per week, but not much more than that. An increased energy deficit, beyond 1,000 calories per day, will lead to starvation, forcing the body to shut down and conserve as much energy as it can to survive. In this scenario, you will find that when starvation occurs, change will not happen. The body is focused on surviving the energy drought. Good nutrition, coupled with a comprehensive exercise plan, is the only way to lose the weight you want and keep it off.