It may seem counterintuitive, but to lose weight and keep it off, you have to eat consistently. On a starvation diet you may lose weight but not the right kind of weight. Starvation diets cause a high loss in muscle mass and water weight from dehydration. Muscle naturally burns more calories than fat, and losing muscle mass will only decrease your metabolic rate.
The feeling of hunger is a survival mechanism. Early man used hunger as a signal that it was time to hunt or forage for food in order to gain energy and survive another day. If early man was unable to find food, the body would begin to go into starvation mode, conserving calories and storing them as fat. This mechanism still occurs today when you go too long without eating, although food is rarely ever further than the nearest corner store or drive-through.
Diet Vs. Starvation
Your body does not recognize the difference between a restrictive diet and actual starvation. When you take in too few calories to maintain normal body functions like breathing and maintaining a heartbeat, your body begins to conserve calories to be able to continue these necessary functions. This results in a decrease in your metabolism. When your metabolism decreases and you go back to eating normally (or go off of the restrictive diet), you will likely gain back whatever weight you lost plus more because of your slower metabolic rate.
Going for extended amounts of time without eating can cause short-term side effects such as decreased attention span, fatigue and irritability. A long-term starvation diet can result in loss of menstrual cycle for woman, hair loss, osteoporosis and many other physical effects related to specific nutrient deficiencies. Both the brain and muscles require carbohydrates obtained from food for energy. Without carbohydrates, both begin to lose optimal function.
A Better Weight-Loss Strategy
Under an ideal weight-loss method, you slowly change daily habits and choose new ways of eating or preparing foods that you are able to maintain for life. Compare that to an extreme diet that can be done for only a short period of time before returning to old habits. Strive for 1 to 2 pounds of weight loss per week. More than that is not likely to be true weight loss but water weight that will fluctuate with intake and level of activity.