How many calories should you eat each day?

What will it say?

With all of the diet options out there—Atkins, South Beach, Special K, cabbage—losing weight can seem really confusing. This confusion is unfortunate, because really, weight loss ultimately comes down to an incredibly simple formula:

To lose one pound, you must burn 3500 more calories than you take in.

This “calorie deficit,” as it’s called, can span a day, a week, even a month. And, unfortunately, it can work in reverse: if you take in 3,500 more calories than you burn, you’ll gain a pound. Add an extra 500 calories to your daily diet (by eating, say, a Starbucks muffin, or drinking two pints at a bar) and you’ll gain four pounds a month, or 36 pounds a year!

Sadly, it seems finding ways to eliminate calories is a lot more difficult that taking them in. But, it definitely can be done, especially if you involve exercise. If you burn an extra 300 calories a day (try doing the run-walk exercise I talked about), then you only have to eliminate 200 calories each day. You can do this in a number of ways, or use a combination of elimination strategies: switch from regular soda to diet, or better yet, drink water instead, skip the mayo on your sandwich or the dressing on your salad, or cut out a snack like crackers and cheese before dinner or half a brownie afterlunch.

But it’s hard to know what “extra” calories even means without knowing how many calories you should be taking in to begin with. Fortunately, there’s a relatively simple formula to answer this question. You can read more about the science behind it here.

First, you need to calculate your Basal Metabolic Rate. This can be done using an online calculator like this one, or using this formula:

For Women (using pounds and inches):

655 + ( 4.35 x your weight ) + ( 4.7 x your height ) - ( 4.7 x your age )

For Men:

66 + ( 6.23 x your weight ) + ( 12.7 x your height ) - ( 6.8 x your age )

Then, you take this number and multiply it by a number that represents your activity level. Be honest, here, and underestimate if you’re unsure, because if you get this number wrong, you won’t be able to lose weight.

1.      If you get little or no exercise, your calorie count should be your BMR x 1.2

2.      If you get light exercise, like walking or playing sports 1-3 days a week, your calorie count should be your BMR x 1.375

3.      If you get moderate exercise 3-5 days a week, your calorie count should be your BMR x 1.55

4.      If you are very active 6-7 days a week, your calorie count should be your BMR x 1.725

5.      If you are extra active, doing very hard exercise every day or working a very physical job (this describes very few of us), your calorie count should be your BMR x 1.9

But remember, and this is important, these are the calories you need to maintain your weight. To lose weight, you need to achieve that 3,500 calorie defecit.

So, if you are 40-year-old woman who is 5’5” and 150 lb, and you get light exercise, you need 1,959 calories to maintain your weight. To lose a pound a week, you need to eat about 1,460 calories a day. If that’s too difficult (and it is pretty low), try upping your exercise. Then you’ll get to eat 1,700 calories a day.

All of this calorie calculating and counting can feel like a pain, but trust me, it’s a lot simpler (and more effective) than the latest fad diet.