Weight management may be difficult to achieve, but it certainly is not difficult to understand. When you consume food or drink, you consume calories. Your body burns calories to function, burning significantly more calories when you exercise. If you consume more calories than you burn, you gain weight. If you consume fewer calories than you burn, you lose weight.
Because your body requires energy simply to stay alive, you burn calories even when you are not exercising. In fact, you burn calories directly in proportion to your body weight. On average, a male burns 11 calories per day per pound of body weight. The average female burns 10 calories per day per pound of body weight. These figures are just averages. Some people will be higher or lower, since everyone's metabolism is a little different. Fitness Record allows you to specify the value which is appropriate for you. If you don't know, it is suggested that you start by using the average value for your gender.
For example, if John weighs 150 pounds, he burns approximately 150 x 11 = 1,650 calories per day. If he exercises, he will burn additional calories on top of that, depending on the exercise activity. However, if he does not exercise, he must eat 1,650 calories per day, just to maintain his body weight. If he eats more, he will gain weight. If he eats less, he'll lose weight.
For the purpose of calculating expected weight gain/loss, one pound is 3,500 calories. Each time you consume an extra 3,500 calories more than you burn, you will gain a pound. For example, Jane weighs 130 pounds, never exercises, and eats exactly 1,400 calories every day. Her metabolism is burning 1,300 calories per day, so she are consuming an extra 100 calories each day. If she does this indefinitely, she will gain a pound in 35 days, since 35 * 100 = 3,500.
Fitness Record uses another term, called Behavioral Weight. The idea is that over the long term, your weight is determined by your behaviors, and is best illustrated by example. Consider Jane above, who eats 1,400 calories per day. After 35 days of this behavior, she will weigh 131, instead of 130. This means her metabolism will burn slightly more calories than before. If she continues to eat 1,400 calories every day, she will continue to gain weight, but at a slightly slower pace. Eventually, she will weigh 140, at which time her metabolism will be burning 1,400 calories every day. At this point, she will stop gaining weight, since she is consuming the same number of calories that she burns. Therefore, by eating 1,400 calories in a day, Jane is behaving like a 140 pound person. Her "behavioral weight" is 140.
Exercise contributes to your calories burned. If Jane were to exercise, burning an additional 100 calories each day, then her calories burned would be in balance with her calories consumed. She could eat 1,400 calories per day, exercise 100 calories per day, and continue to way 130 indefinitely.
You may now be asking, "Why can't I just eat low fat foods?" You can eat whatever you want. But, non-fat foods can still have calories. Check the food label to find out if eating the non-fat version of a food is really saving you any calories -- sometimes it's not. Many programs recommend moderating your dietary fat intake, and that is obviously good advice. Eating low-fat foods happens to be an excellent guideline for keeping your calorie intake low. In addition, moderating your dietary fat intake may contribute to your health in other ways. However, it will not alter the mathematics of weight management -- you still have to eat fewer calories than you burn if you want to lose weight.
The problem with the way the human body works is that calories counting is tedious and difficult. Most weight-loss programs, as well as the so-called "fad diets", focus on other guidelines which are simpler to follow than calorie counting. However, none of these guidelines alter the underlying principles of weight management.