It's tempting to go for fast results when you want to achieve a healthy body weight. But just as gaining weight doesn't happen overnight, losing is safest -- and most successful -- when it's a gradual process. Healthy, long-term weight loss isn't about making extraordinary efforts through diet and exercise until you reach your goal; rather, it's about making a series of lifestyle changes that are relatively easy to manage and maintain over time. Losing a chunk of weight, such as 5 pounds, in a safe manner may take several weeks to a month.
What It Takes to Lose 5 Pounds
Although your body weight is influenced by your gender, age, genetics and other factors, it's also affected by your diet and level of physical activity. This is why understanding the concept of calorie balance is front and center in virtually all weight-loss programs. To lose weight, you must first create a calorie deficit, either by cutting calories from your diet, burning them off through exercise, or a combination of both. Specifically, it takes a deficit of 3,500 calories to lose 1 pound of weight. To lose 5 pounds in one week, therefore, you'd need to cut or burn 17,500 calories, or create a 2,500-calorie deficit per day.
To put this number into perspective, a woman in her early 20s who weighs about 125 pounds and is moderately active requires about 2,200 calories a day. At that body weight, she'll burn about 240 calories per hour of brisk walking, and about 330 calories per hour of low-impact aerobics. Even if this woman were to exercise for two hours every day, burning somewhere in the range of 600 to 700 calories, she'd still have to cut 1,800 to 1,900 calories from her daily diet to achieve her goal of losing 5 pounds in a week. That would leave 300 to 400 calories left over for her to eat, which isn't safe or doable.
Consuming fewer than 800 calories per day -- which is considered a very low-calorie diet -- is usually only recommended for severely obese people under a physician's care.
Dangers of Rapid Weight Loss
Perhaps the most obvious danger of rapid weight loss is its potential nutritional side effects. Because calories deliver the nutrients you need to stay healthy, eliminating too many calories -- particularly when it continues over time -- can cause your body to become malnourished. Malnutrition can manifest itself in a variety of ways, depending on what you're lacking – an iron deficiency can cause you to feel tired, while a vitamin C deficiency can lead to dry skin and hair, as well as easy bruising. Even if you don't experience a specific nutritional deficiency, simply consuming too few calories can leave you feeling chronically depleted or unwell.
Rapid weight loss also increases your risk of developing gallstones, hard crystals that form in the gallbladder that can cause severe pain if they become stuck in the duct between the gallbladder and the small intestine. Specifically, people who lose more than 3 pounds per week have a greater chance of developing gall stones, according to the National Institute of Diabetes and Digestive and Kidney Diseases.
A Safer Weekly Weight Loss Rate
Experts recommend losing weight at a rate of 1 to 2 pounds per week. This more gradual weight-loss rate gives your body time to adjust, boosting the likelihood that the weight you're losing comes from fat storage, not water loss or muscle tissue.
To lose 1 to 2 pounds per week you'll need to create a daily calorie deficit of 500 to 1,000 calories, which is doable for the average person. The same moderately active woman in her early 20s who aims to lose 5 pounds in five weeks can do it without starving or dedicating her life to exercise. Taking a brisk walk for an hour every day would get her halfway to her goal by burning 240 calories. Cutting one snack from her diet or reducing the portion size of one meal would be all she'd need to bridge the gap and reach her daily goal of cutting 500 calories. If she were to boost her activity level and cut a few more calories, she'd be able to safely meet her 5-pound weight-loss goal in less than three weeks.
Healthy Weight Loss Strategies
Although it's helpful to have an idea of how many calories you need, how many you consume and how many you burn, you don't have to focus on calories to lose weight safely or effectively. Often, making small, sustainable changes is enough to foster successful long-term weight loss.
You may already know that eating a diet comprising whole foods -- while cutting out processed foods and added sugars -- promotes weight loss. More specifically, giving fruits and vegetables more space on your plate, eating high-fiber foods, choosing water or unsweetened beverages over soda and other high-calorie drinks, reducing portion sizes or using smaller plates, avoiding sodium-rich foods, and limiting your alcohol intake can go a long way in trimming calories from your diet.
Starting an exercise program is important for long-term weight loss success. The American College of Sports Medicine guidelines recommend that adults who want to lose weight exercise at a moderate intensity for at least 150 to 250 minutes per week. The guidelines also state that exercising for more than 250 minutes per week may help you lose more weight and make you less likely to regain the weight you've lost. Before beginning any exercise program, consult with your physician to talk about the exercise intensity and frequency that's right for you.
- Centers for Disease Control and Prevention: Losing Weight
- NHS Choices: Should You Lose Weight Fast?
- American Council on Exercise: Trimming Off the Fat
- Centers for Disease Control and Prevention: Finding a Balance
- Center for Nutrition Policy and Promotion: Estimated Calorie Needs per Day by Age, Gender, and Physical Activity Level
- Harvard Health Publications: Calories Burned in 30 minutes for People of Three Different Weights
- American College of Sports Medicine: ACSM Position on Physical Activity and Weight Loss
- National Institute of Diabetes and Digestive and Kidney Diseases: Dieting and Gallstones
- National Heart, Lung, and Blood Institute: What Are the Signs and Symptoms of Iron-Deficiency Anemia?
- Linus Pauling Institute at Oregon State University: Vitamin C