Weight loss plans, fad diets and supplements all offer solutions to weight loss. The simple truth is that weight loss requires eating fewer calories than you burn. Unfortunately, that simple truth requires some confusing calculations and a bit of a balancing act to make sure you are eating enough calories, but not too many.
The human body requires a certain number of calories, depending upon body weight, lifestyle, age, fitness level and exercise. If you consume more calories than your body requires, you will gain weight. If you consume fewer, you will lose weight. Cutting 500 calories per day will produce a one pound weight loss per week.
Base Metabolic Rate
Determine how many calories you should consume to lose weight, starting with your base metabolic rate or BMR. Calculate your BMR with the following equation, using pounds and inches for all measurements: BMR = 655 + (4.35 x weight) + (4.7 x height) – ( 4.7 x age) or use an online calculator (see Resources). Your base metabolic rate determines how many calories you would use if you spent the day in bed, with no activity at all.
Harris Benedict Equation
The Harris Benedict Equation brings activity into the calorie requirement equation. Multiply your BMR by 1.2 if you live a very sedentary life with minimal activity. Light exercise three times a week increases this number to 1.375 and moderate exercise or sports three to five times a week multiplies your BMR by 1.5. The base metabolic rate times 1.725 is appropriate if you are quite athletic and active, while a strenuous physical job plus exercise allows you to multiply your BMR by 1.9.
Your BMR multiplied by the Harris Benedict equation provides you with the total number of calories your body uses daily, before you factor in a daily workout or exercise. Subtract calories from this number to aim for a weekly calorie deficit of 3,500 to 7,000 calories for a healthy 1 lb. to 2 lb. weekly weight loss. For most women, 1,200 to 1,800 calories a day will produce sustainable weight loss and allow for adequate nutrition.
While consuming too many calories will slow weight loss, so too will consuming too few. If you do not eat enough, your body will slow your metabolism and hold onto unwanted pounds. Women should avoid dropping below 1,200 calories per day and may want to consider slightly increasing calories if weight loss stalls.