How Much Weight Can I Lose in 40 Days?

An appropriate weight for your age and height is a bonus for your health and self-image. Whether for reasons of vanity or health, you should always carefully plan weight loss. A balanced weight-loss plan must include both eating adjustments and physical activity. Your health-care provider can help you create a balanced, safe and effective action plan to reach a realistic weight-loss goal in 40 days.


Safety First

Whether you want to reach your target weight loss within 40 days or 40 months, it is necessary to protect your health while you lose weight. That means that dietary changes must be medically safe for your age and health profile. Likewise, the exercises you do have to be safe, as well, for the number of calories burned. Your health-care provider will determine the maximum heart rate for your age, height, weight, medications and medical conditions so that you can exercise safely.

Calorie Intake

MedlinePlus, a website from the U.S. National Library of Medicine and the National Institutes of Health, recommends a minimum intake of 1,200 calories per day for women and 1,500 calories per day for men. The make-up of these calories also counts. On a daily basis, aim to eat three to five servings of fruits and vegetables, 40 g of lean protein and at least 130 g of carbohydrates. Your calories from fat should be less than 30 percent of your total calorie intake. Avoid diets that require an intake of less than 800 calories per day if not medically supervised. Ask your health-care provider to help you select the best vitamin and mineral supplements for your age, gender and health.

Setting a Goal

Weight loss should not exceed 2 lbs. per week. More rapid weight loss of 3 lbs. or more per week can precipitate gall bladder attacks, according to Weight-control Information Network. So to find the most amount of weight you could safely lose within a 40-day period, simply multiply the 2 lbs. by 5.71, which is the number of weeks in 40 days. The result is 11.42 pounds.

The Formula

Use your current weight and physical activity level to determine what your calorie intake needs to be and how much physical activity you need to include. offers an online calorie calculator that enables you to see what your daily calorie needs are to maintain your current weight. For example, a 5-foot, 5-inch 40-year-old woman who leads a somewhat active lifestyle requires 1,900 calories per day, or 13,300 per week, to maintain her weight. To lose 2 lbs. per week, she would need to reduce her calories by 7,000 because 3,500 calories equals 1 lb. If you divide that 7,000 calories between the seven days of the week, that means she would have to reduce her calories by 1,000 per day, putting her below the 1,200-calorie daily minimum. Therefore, she would have to supplement her efforts by burning calories with more exercise.


Once you've decided how many calories you can safely cut per day from your diet and how many extra calories you need to burn, you can plan the physical activity you will use to burn those calories. There are several online activity calculators -- such as those from Discovery Health and -- that enable you to determine how many calories you burn doing things as mundane as dusting to more traditional physical activities such as jogging and playing tennis. Use these tools to help you and your doctor select the safest possible choice for your daily exercise regimen.

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