Medical questions & health advice by board certified doctors
"Is it bad for your body to lose weight very quickly?"
I think I need to lose weight, fast! I want to just stop eating and only drink things and exercise a lot. Is it bad to lose a lot of weight in a short period of time?
Not eating is probably the most unsafe and the least effective approach to losing weight quickly. When totally depriving your body of carbohydrates, you trigger your body to go into ketosis where you stop using glucose and glycogen for energy and your body switches to using ketones (acidic substances from fat breakdown) for energy. To a healthy young person it is not dangerous for his or her body to exclusively use ketones for energy. However, people with other medical conditions may have problems with their bodies going into ketosis that eventually become acidemic (acidic blood) and cause memory loss, heart and kidney problems, etc. Eating a no-protein diet is particularly risky. Although it is not dangerous as in life threatening, it is not good for your overall health to lose weight quickly when your body starts burning up muscles after the fat stores are spent. The only proven method of safe, rapid weight loss is the medically supervised very low-calorie diet. That said, rapid weight loss creates physical demands on the body. Possible serious risks are gallstones occurring in 12%-25% of people, malnutrition, and electrolyte imbalances. Please see a primary care doctor or dietitian for a physical and medical evaluation so he or she can help you start the safest and most effective weight loss regimen and diet.