Counting calories is a habit promoted by many weight loss experts, but when you go to check your weight on a scale, your weight is registered in pounds. It can be frustrating to limit calorie intake and exercise yet see little or no improvement when going to the scale. To be successful in weight loss, you must achieve a net calorie loss every week over the course of several months.
Calories in Fat
The simple answer to how many calories must be burnt to lose a pound of weight is essentially the number of calories in a pound of fat. Since fat is the primary source of undesirable stored calories in the body, when people talk about burning weight, they are almost always referring to body fat. There are approximately 3,500 calories in a pound of fat. This means that if you were to increase your calorie burning by 3,500 a week, and held your diet unchanged, you would potentially end up about 0.454kg. lighter at the end of the week than you would have otherwise. The flaw with treating a certain amount of calorie burning as equalling a certain amount of weight loss, is that you don't derive all of your energy from body fat stores--most of it comes from the calories you eat.
Calorie intake is a vital component of how many calories you have to burn to shed a pound of fat in your body. Say you consume 2,000 calories a day. Even if you were to burn 3,500 in a single day, (which would take a tremendous effort, such as running a marathon) you would not burn a pound of body fat. Over half of the calories you burnt would have come from the food you ate, so only 1,500 of the calories burnt would come from your body fat. They key to losing a pound of fat is burning 3,500 calories more than you consume. Therefore, the true amount of calories that must be burnt to lose a pound of weight is invariably much higher than 3,500.
Since the body needs to consume food to maintain itself, it is not viable to attempt to burn large quantities of body fat in a day or two through intense workouts. When the bodywork out, it demands energy. Carbohydrates can be broken down and provide that energy faster than pure body fat. If the body is forced to rely only on body fat, energy levels will drop and the level of intensity of a workout will fall, which can ultimately hamper calorie burning. The key to losing weight is sustaining a net calorie loss every day for a long period of time.
Say you eat 2,000 calories a day, but between exercise and normal bodily energy expenditure you burn 2,500. After a week's time, you will have shed a total of 3,500 calories above what you've eaten, which will be about equivalent to 0.454kg. of fat weight. The problem is that when the body is facing a shortfall of calories and is being forced to exercise more, you may feel hungry more often or feel like you need to eat more to replenish your energy.