First, there are no calculations that are going to be completely accurate. You are dealing with averages. The more variables that come into play in the equation, the more accurate the outcome will be, most likely.

For simplicity's sake, since we are dealing with averages to begin with, you can use 14-16 calories per pound of body weight for maintenance. Granted, some people are going to have a lower maintenance than this. Others will have a higher.

Or, you can use any of the online calculators, such as:

Calorie Control Council | Healthy Weight Calculator

Or you can use something like the Harris-Benedict formula to determine your BMR, and then use an activity multiplier to figure out your maintenance.

The HB formula is:

Men: BMR = 66 + (13.7 X wt in kg) + (5 X ht in cm) - (6.8 X age in years)

Women: BMR = 655 + (9.6 X wt in kg) + (1.8 X ht in cm) - (4.7 X age in years)

For those of you who don't know, there are 2.54 cm in one inch. There are 2.2 lbs in one kg.

Once you determine your BMR from the above equations, you need to multiply it be an acitivty factor. BMR is comprised of the energy you expend at rest, doing things such as breathing, digesting, circulation, etc. Obviously, if we are calculating maintenance, we need to add in the energy we expend moving around, working, exercising, etc.

Hence, you have the following activity factors, which can be modified:

Sedentary = BMR X 1.2 (little or no exercise, desk job)

Lightly active = BMR X 1.375 (light exercise/sports 1-3 days/wk)

Mod. active = BMR X 1.55 (moderate exercise/sports 3-5 days/wk)

Very active = BMR X 1.725 (hard exercise/sports 6-7 days/wk)

Extr. Active = BMR X 1.9 (hard daily exercise/sports & physical job or
2 X day training, marathon, football camp,

Aside from calculations, you could also keep a food log. If you maintain exactly what you eat and drink and all of the caloric values of each item for a few weeks, while tracking your weight, you will know if you are in a deficit, maintenance, or a surplus.... depending on which direction your weight is heading in, if any.

Follow me?

Once you figure out your estimated maintenance, it becomes quite easy. You simply reduce from your maintenance by a certain percentage. I like to start with a reduction of 15-20% of maintenance. However, this is a generalized statement. It can vary depending on starting point. The more weight you have to lose, the more aggressive you can be with your deficit. The less weight you have to lose, the more conservative you should be.

Yes, it is obvious from the calculations above, that your required calories depends heavily on your weight. The, as your weight comes down, so does your caloric requirements. Make sense? So, where once you were in a deficit, as the weight comes off, this same caloric intake may become your maintenance.

I will add, that calculating your calories shouldn't be something you do on a weekly basis. Figure out a starting point. Stick with it for a few weeks. Note your changes, if any. If measurements (weight, body fat, actual measurement in inches) are heading the wrong way, you know that your intake was off. Modify as you see results.

I always say, you are not signing a contract when you calculate your calories. You are merely finding a starting point. From it, changes will certainly occur over time, either due to metabolic slowdowns and/or miscalculations.

Sure, as long as you progessively bump up energy expenditure through exercise. However, a combination of both reduction of consumption and increase in activity has proven to be the most effective approach for me.

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