How fast a person loses weight depends on a number of factors. Some can be changed and some are based on science and genetics. As a general rule, fast weight loss is usually not permanent, as it results from a loss of muscle or water, rather than fat. Still, there are factors to consider when trying to determine how fast someone can lose weight.
The Science Behind Weight Loss
A pound of body weight equals 3,500 calories. This means that to lose a pound, a person needs to eliminate the equivalent to 3,500 calories through exercise or a change in diet. At rest, the average 150-pound person burns an average of 1,200 calories just to stay alive. This takes into consideration the amount of calories the body needs to maintain the organs functioning and keep the brain active at any given time. By cutting down the amount of calories consumed to this number (or just above), you will lose weight because there are no additional calories being consumed to be stored as fat. Through this method, the average person will lose 1 to 3 pounds of body weight a week.
Your Starting Weight
The more weight you have to lose, the faster you will lose it. Everybody has a set weight, which is the weight at which the body feels most comfortable. In people who are extremely overweight, this set weight is far from the actual number on the scale, making it easier to drop pounds with just a few changes. Also, people who are consuming large amounts of food or high-calorie drinks on a daily basis have more room to adjust their caloric intake than those who only have a few pounds to lose and are already eating a well-balanced diet.
Extremely low-calorie diets, which include everything from cleanses to liquid diets to eating only a specific food group (such as greens), cause rapid weight loss. This happens for a number of reasons. First, the low number of calories consumed usually leads to dehydration and water loss, lowering the number on the scale but not necessarily leading to fat loss. In fact, extreme diets cause a loss of muscle mass, since the body eats away at the muscle to feed itself and make up for the lack of energy obtained from food. Because muscle is heavier than fat, the numbers on the scale tend to drop quickly with these diets. However, weight loss is mostly temporary, and most is regained as soon as you go back to your regular way of eating. Because muscle accelerates metabolism, a loss of muscle will eventually lead to an increase in weight, even if you go back to eating the same amount of food you did before. Extreme diets can cause a weight loss of up to six pounds a week, especially during the first two weeks of dieting, when water is being lost.
While diet is the main component in a weight-loss program, the amount of activity performed on a daily basis will also affect the speed. People who exercise regularly have more muscle mass, which speeds the metabolism and causes faster weight loss. Also, exercise burns calories and makes it easier to lose weight, especially when combined with a controlled-calorie diet. For best results, choose an activity that burns a high number of calories but also works the muscles effectively (rather than just elevating the heart rate). Examples of effective exercise for weight loss include hiking, climbing, swimming and kayaking.
Children of obese parents are more likely to be obese. This is due to a combination of genetics and environment. Those who grew up surrounded by obese people may be less likely to eat a balanced diet, exercise and maintain a healthy weight. A family history of depression or emotional eating can also affect a person's relationship with food and make it more difficult to lose weight at an appropriate pace.