Gaining weight requires you to create a calorie surplus. You must eat more calories than you burn over time to add pounds. Since the average adult woman needs between 1,800 and 2,400 calories per day and the average man between 2,000 and 3,200 calories per day, it is not possible to create a calorie surplus and gain weight when eating just 1,000 calories per day. A diet consisting of this number of calories, however, may undermine weight-loss efforts because it can cause your metabolism to stall.
Calories and Weight Loss
A pound equals 3,500 calories. If you eat 3,500 calories more than you burn over the course of a week, or a month, you will gain 1 lb. If you eat 3,500 calories fewer than you burn, you will lose 1 lb. To keep your weight the same, you need to create a balance of calories consumed versus calories expended over time.
The number of calories you need to maintain your weight depends on your size, age and gender as well as your activity level. Your body burns calories by digesting, breathing and pumping blood. You also burn calories through daily activity, such as showering, washing the dishes and driving your car. The more active you are, the more calories you burn. Even toddlers, however, need 1,000 calories or more to support their metabolic needs.
Because a 1,000-calorie diet is exceptionally low, your body might compensate by slowing down daily functions and making you feel tired so you do not overexert yourself. As a result, you burn fewer calories daily. When you initially begin a 1,000-calorie diet, you may lose weight quickly. Much of this weight comes from water and lean muscle mass. When you lose lean muscle, your body also burns fewer calories at rest – meaning you may experience an even further drop in metabolism. Usually, this creates a dieting plateau in which you feel deprived and eat very few calories, and all the while the numbers on the scale refuse to budge downward.
If you are truly consuming just 1,000-calories per day, you should eventually lose weight over time – but not in a healthy manner. Women need a minimum of 1,200 calories per day to get all the nutrients necessary to support good health, and men need 1,500 calories minimally. If your weight loss stalls on a 1,000-calorie plan, it might be because your metabolism is slowing down and holding on to every bit of energy you put into your body. It may also be because you are actually eating more calories than you think. Remember, every morsel you put into your mouth counts – a stick of chewing gum, a sip of soda, the crusts of your kids' sandwiches and the creamer in your coffee all contain calories that can add up over the course of day. Following a very low calorie diet also increases your levels of the stress hormone cortisol, which can further interfere with your well-being and physiological health, found a study published in the May 2010 issue of "Psychosomatic Medicine."