(Should you try keto or the DASH diet, for instance?) But no matter what kind of eating plan you follow, there’s one rule of weight loss that’s clutch: You have to create a calorie deficit, or when you expend more calories than you take in.

Well, there’s some detective work involved at first to figure out how many calories your body needs, followed by a little math to calculate what you need to take in to be in a deficit.

Your body needs to take in a certain number of calories to maintain your weight, says Keri Gans, RD, author of The Small Change Diet.

And, so, “a calorie deficit is when you consume fewer calories than your body requires to stay at its current weight,” she explains.

It can be a little complicated to figure out your exact calorie deficit but, in general, it’s thought that shaving 500 calories from your daily intake should lead to one pound of weight loss per week.

“If you eat 500 calories less than the amount you need to maintain your weight, you will lose one pound in a week.” If you want to lose two pounds a week, you might try a 1,000-calorie daily deficit.

A calorie deficit is when you consume fewer calories than your body requires to stay at its current weight.

“Any deficit will lead to weight loss,” Angelone says.

There are different ways of calculating calorie needs, but Angelone says she usually uses the Harris-Benedict Equation, Mifflin-St Jeor Equation, or Katch-McArdle Formula with clients.

The National Institute of Health’s Body Weight Planner is a good one to try, Angelone says

It looks at your current weight and fitness level, along with your weight loss goals, and helps map out how many calories you need to take in to lose the weight over the period of time you specify