Before we get to the calculation, let me start by saying that I don't think it's necessary to be enslaved to counting calories, fat grams, points, or carbs every day for the rest of your life in order to lose weight. However, in the beginning of your weight loss journey, it might be helpful to have an idea of how many calories you're consuming compared to how many calories you actually need.

As a clinical dietitian, calculations are second nature. We use them everyday in practice to determine a patient's needs. Below, I've provided you with one of the ways to calculate calorie needs. If you would rather not do the math, you can easily find a calorie calculator online. Just be sure to find one that asks for your height, weight, sex, and activity level in order to get a more accurate answer. Also, enter your current weight into the form and then subtract 500-1000 calories from the number you get in order to lose 1-2 pounds per week. Or, enter your goal weight to determine how many calories you should start consuming to meet your goal.

Most, if not all, dietitians are very familiar with the Harris-Benedict equation. It is used to determine your BMR or Basal Metabolic Rate, which represents your most basic calorie needs or the amount you would require to sustain life if you simply laid in bed all day with no physical activity. Once you calculate your BMR, don't forget to multiply your answer by an activity factor (described below). This equation requires some brain exercise, so put your thinking cap on, get a pen, paper and a calculator and let's do some old school math.

The Harris-Benedict Equation:

* For men: BMR = 66 + (6.2w) + (12.7h) - (6.8a) x Activity Factor

* For women: BMR = 655 + (4.4w) + (4.7h) - (4.7a) x Activity Factor

w = weight in pounds
h = height in inches
a = age in years

Activity Factors
1.200 = sedentary (little or no exercise)
1.375 = lightly active (light exercise/sports 1-3 days/week)
1.550 = moderately active (moderate exercise/sports 3-5 days/week)

If you want to know how many calories you need in order to maintain your current weight, then use your current weight as w in the equation. Then, subtract 500 calories from your final answer and that's how many calories you would need to consume in order to lose approximately one pound of fat per week. Subtract 1000 calories to lose closer to two pounds per week. Another option is to enter your goal weight into the equation for w in order to figure out how many calories you should start consuming today in order to reach that weight.

thanks for the remidner of what's already been posted on this site more than once

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“Knowledge is power” – Sir Francis Bacon, philosopher
“Knowledge shared is power multiplied”, Robert Noyce, co-inventor of the semiconductor, co-founder of Intel

Why the huge difference in the numbers for men vs. women (66 vs. 655)?

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In order to account for differences in body composition. Men tend to have higher BMR's than women. The initial 66 seems drastically different from the 655 for women, but is balanced out with the higher values in the rest of the equation (for height, weight, and age).