Many diets claim to help people lose large amounts of weight in a single week, but Women’s Health magazine suggests that the average person is not able to lose more than 3 to 4 pounds in a week. Losing weight gradually and steadily, by cutting calories and increasing physical activity, is recommended over crash diets, which can be dangerous and detrimental to a person's long-term results.
According to the Centers for Disease Control and Prevention, people who lose weight at a safe rate of 1 to 2 pounds per week are more successful at keeping the weight off than those who lose larger amounts. To lose 1 to 2 pounds per week, an individual needs to burn 500 to 1,000 more calories per day than he consumes. This creates a calorie deficit of 3,500 to 7,000 calories per week (1 pound = 3,500 calories).
To lose weight faster, an individual needs to eat even less and exercise more. However, WebMD warns against diet crazes that involve cutting calories below 1,050 to 1,200 per day. Eating too few calories causes muscle loss, which slows the metabolism and sabotages weight loss. Extreme diets are also more likely to fail over the long term because individuals feel too deprived and eventually return to their old habits rather than maintaining healthy lifestyles.
In the December 2013 issue of Women’s Health, registered dietitian Lauren Slayton explains that how much weight someone is able to lose in a week depends on several factors, including starting weight and lifestyle. People who weigh more and have unhealthy lifestyles to begin with are more likely to see dramatic losses when they start eating healthy and exercising more.