Obtain your measurements
To get accurate height and weight measurements you may want to visit a doctor's office or gym to be measured, then calibrate your home scale to the doctor/gym scale since home scales are often inaccurate. To illustrate the calculations in this article we'll use the example of a man of 6 feet tall weighing 90.7 kg (200 lbs) and woman of 5 feet 6 inches tall weighing 68.03 kg (150 lbs.)
Calculate your ideal body weight
Following is a simple rule many practitioners use to roughly calculate ideal weight, noting that age and other factors should be taken into consideration.
In kilograms: allowing 50 kg for 5 feet tall + 2.3 kg for each inch of height above 5 feet, ideal weight for a man 6 feet tall is 50 + (2.3 x 12) = 77.6 kg.
In pounds: allowing 110 lbs for 5 feet tall + 5 lbs for each inch of height above 5 feet, ideal weight for a man 6 feet tall is 110 + (5 x 12) = 170 lbs.
In kilograms: allowing 45.5 kg for 5 feet tall + 2.3 kg for each inch of height above 5 feet, ideal weight for a woman 5 feet 6 inches tall is 45.5 + (2.3 x 6) = 59.3 kg.
In pounds: allowing 100 lbs for 5 feet tall and 5 lbs for each inch above 5 feet, ideal weight for a woman 5 feet 6 inches tall is 100 + (5 x 6) = 130 lbs.
Figure calories needed to maintain current weight
To roughly figure daily caloric needs to maintain current weight, multiply your weight (in pounds) by 12 if you're a woman, and by 14 if you're a man. Or multiply your weight (in kilograms) by 26.45 if you're a woman and by 30.87 if you're a man. Calculators on the Internet can provide a more accurate figure based on age and activity level. A man weighing 200 pounds needs roughly 2800 calories to maintain current weight (200 lbs. x 14 = 2800.) Metrically it's calculated as 90.7 kg x 30.87 = 2800. A woman weighing 150 pounds needs roughly 1800 calories to maintain current weight (150 lbs. x 12 = 1800.) Metrically it's calculated as 68.03 kg x 26.45 = 1800.
Eliminate calories through diet and/or exercise
The two time-tested ways of losing weight include (1) cutting calorie intake (dietary changes, fat blockers) and/or (2) increasing calorie burn (exercise, metabolic boost). If you don't want to eat fewer calories, you can increase the amount of calories you burn by exercising more. The most effective weight loss occurs with a combination of both diet and exercise, though.
Determine calories needed to lose weight
To lose weight, eliminate 500-1,000 calories from your daily net through diet and/or exercise, but for safe weight loss do not consume fewer than 1200 calories per day without supervision by a medical professional. A person needing 1800 calories to maintain weight may eliminate 500 calories from diet and burn an extra 500 calories through exercise for a daily net loss of 1000 calories. At that rate body fat loss is 2 pounds in a week (1000 calories x 7 days = 7000 calories.) Figuring it metrically, a person will lose a kilogram of fat by eliminating 7700 calories over a period of time (ex: reducing calorie net by 1000 per day for 7.7 days, by 700 per day for 11 days or by 500 per day for 15.4 days.) As your weight reduces, re-figure calories needed for weight maintenance based on the new numbers and go from there.
