Cutting back on calories also means cutting back on essential nutrients. Eating too few calories and nutrients can lead to potentially life-threatening health problems that make weight loss the least of your concerns. Every bodily function requires a certain amount of calories to perform smoothly. You even burn calories when you are sleeping. You must make sure you get enough calories in your diet -- even when you're trying to lose weight.
According to Mayo Clinic, your daily calorie requirements depend on your gender, age, body size and composition, and your daily activity level. When you consume more calories than you need, the body stores the extra calories as fat, which causes weight gain. When you consume considerably fewer calories, your body uses the calories from the stored fat, which causes weight loss. Your daily intake should stay above 1,500 calories if you are a man, or 1,200 calories if you are a woman.
Eating fewer calories usually results in weight loss, but eating too few calories for a prolonged period of time can actually stall weight loss. Eating less than 1,200 or 1,500 calories a day puts your body into starvation mode. Your metabolism, or the rate at which your body burns calories, slows down as a defense mechanism against starvation. Your metabolism picks up once you increase your calories. So, the key to losing weight through calorie control isn't eating as few calories as you can -- it's eating enough to keep your metabolism in constant calorie-burning mode.
Consuming too few calories over a long period of time can be harmful to your health. Not only are you depriving your body of calories it needs to function, but you are also depriving it of essential nutrients. Physical effects of eating too few calories include dangerously low blood pressure and blood sugar levels, which can cause dizziness and fainting; thinning hair or hair loss; decreased bone density; irregular heartbeat; brittle nails; dry skin; fatigue; cessation of menstrual periods; and constipation.
If weight loss or maintenance is your goal, increasing your level of physical activity to burn extra calories may be more effective than just eating fewer calories. Lowering your caloric intake is best done after consulting with your doctor, who can develop a calorie-reduction diet that meets your nutritional needs. A diet of less than 1,200 or 1,500 calories is not recommended, unless done under medical supervision.