You can lose 10 pounds in less than a week if you are hundreds of pounds overweight; that 10 pounds actually equals a small percentage of your weight when you weigh close to 400 pounds. For most people, achieving a one- to two-pound-per-week rate of weight loss is achievable and safe.
Who Can Do It?
The people on weight-loss reality shows do manage to lose 10 or more pounds in a week, but realize these people are dedicating their days to this effort. The average person has family and work obligations that make constant attention to weight loss impossible. Television weight-loss programs also offer professional fitness, medical and nutrition guidance to ensure that when drastic calorie restriction and exercise are undertaken, the participants remain safe.
How You Lose Matters
Be wary of losing weight too quickly; oftentimes, fast weight loss yields fast weight regain. You may be able to take off 10 pounds in less than a week with fasting or juicing -- but you're likely to put much of that back on when you return to real food. You also risk low energy and nutritional deficiencies. If you're trying to lose those "last" 10 pounds, don't expect it to come off in less than a week, either. Even if you managed miraculously to lose it, much of it would come from valuable muscle tissue, rather than fat.