Weight-loss reality shows impress you with their contestants' big losses, so much so that you might be inspired to try to drop some pounds yourself. You may have a goal that doesn't allow you to wait for the slow, gradual weight loss of 1 to 2 pounds per week advised by the Centers for Disease Control and Prevention. For the vast majority of people, though, losing five pounds per week is impossible and dangerous to try. Even if you could restrict your calories adequately to lose weight this quickly, it is unlikely to be a weight loss you could maintain.
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An Impossible Goal for Many
Weight loss is a matter of calories in versus calories out. When you consume 3,500 calories fewer than you burn, you lose a pound. Losing five pounds requires a deficit of 17,500 calories -- or 2,500 calories per day for a week.
The number of calories you burn daily depends on your age, gender, size and activity level. Many people, including most women and older adults, don't even burn 2,500 calories daily. The range of daily calorie burn is 1,600 to 2,400 calories per day for women, or up to 3,000 calories per day for men. These include the calories necessary to support the body's basic functions, such as breathing and pumping blood, and daily activity, including exercise. It's impossible for people with these daily calorie burn rates to lose five pounds per week -- they simply couldn't create a large enough deficit.
Even if you burn 2,600 to 3,600 calories daily, cutting 2,500 calories leaves you with fewer than 1,100 calories per day to live on. A diet with fewer than 1,200 calories is likely to leave you with a nutrition deficit. You'll also lose a notable amount of muscle mass as your body turns to it for energy. Feelings of fatigue, irritability and weakness may also be the side effects of such a low-calorie diet.
Is a Five-Pound Loss in a Week Safe?
If you can safely create a deficit of 2,500 calories per day, then you could technically lose five pounds per week. Safe means getting at least 1,200 calories per day from whole foods such as lean proteins, whole grains and fresh vegetables and fruits. Those who burn 3,700 calories, which is just enough to safely reduce 2,500 calories from their diet daily, tend to be extremely active -- such as Olympic strength or endurance athletes. When active people create extreme calorie deprivation, their training will suffer. If you're not an elite athlete, you'll still find it hard to exercise at all on a low number of calories.
Extremely obese people may reduce their calories to around 800 calories a day while on a medically prescribed "very low calorie diet" to induce rapid weight loss. All of your meals are replaced with medically approved supplements, often shakes, to promote quick weight loss in a short period of time. This type of diet raises your risk of developing gallstones, and weight regain is common.
Physical Activity to Burn Calories
An alternative to depriving yourself with a 2,500-calorie daily deficit is to combine moving more along with eating less. Increase your daily calorie burn by 1,250 calories and trim your diet by 1,250 calories per day. This volume of exercise, though, may also be unsustainable.
To burn 1,250 calories, a 185-pound person would have to cycle indoors at a moderate pace for about 2 hours or jog at 5 mph for about 1 hour and 45 minutes. More intense activity burns calories more quickly, if you have the energy from your restricted diet to keep it up. Don't forget that in addition to the activity, you'll still have to severely limit what you eat at meals, and it's likely that as soon as you let up on the exercise, weight will return quickly.
Consider your current level of physical fitness and the time you have to devote to such activity before settling on this plan. If you're barely able to squeeze in 30 minutes of walking a few days per week, committing to 1 1/2 to 2 hours per day of more intense exercise may be too lofty a goal.
Settle on a Realistic Goal
A healthy, manageable weight-loss plan requires less drastic means and a slower rate of weight loss. When you make extreme changes in the initial week or two of weight loss, you may lose five pounds a week. Much of this is simply water weight, not real fat loss.
After a couple weeks, though, you should settle into a more conservative, but consistent, loss rate. Successful long-term weight loss depends on creating a lifestyle that you can maintain. A deficit of 500 to 1,000 calories per day, which will yield a loss of 1 to 2 pounds per week, is manageable for most people and brings many people to a restrictive, but doable, intake of 1,200 to 1,400 calories per day.
Also consider how much weight you have to lose. If you're several hundred pounds overweight, a five-pound-per-week loss is much more achievable because it's only about 1 percent of your total weight. If you weigh 160 pounds, five pounds is about 3 percent of your total weight and much harder to lose in a week. Losing weight is easier when you have a lot of weight to lose, but the rate slows down as you get closer to a healthy weight.
- Centers for Disease Control and Prevention: Losing Weight
- Go Ask Alice: Ideal caloric Intake?
- Shape: Ask the Diet Doctor: Is Losing 10 Pounds a Week Safe?
- U.S. Dietary Guidelines for Americans 2010: Balancing Calories To Manage Weight
- AsktheDietitian.com: Overweight and Weight Loss
- National Insitute of Diabetes and Digestive and Kidney Diseases: Very Low Calorie Diets
- National Public Radio: How Many Calories Do Olympic Athletes Need? It Depends
- Harvard Health Publications: Calories Burned in 30 Minutes for People of Three Different Weights