The secret to reaching your goal isn’t some crazy diet. The real magic lies in simple math.

The key to shedding pounds isn’t jumping into whatever fad diet is popular at the moment. No, the smartest game plan for those in the know doesn’t involve eating a lot of one kind of food (we’re looking at you, grapefruit diet) or living off of only liquids for days at a time (seriously, why would you want to do that?). It’s actually reaching for a calculator and using some basic math to help subtract all that unwanted fat.

Getting to a body weight you feel comfortable with means reminding yourself how many calories your body actually needs each day to function at its best. Once you know that number, losing weight and feeling great is as easy as trimming back a reasonable number of calories while burning off a few more with exercise. Grab your pencils:

Step 1:

Find out how many calories your body needs each day to maintain your current weight. Just take your current weight and multiply it by 13 (if you don’t exercise at all), 15 (if you exercise a few times weekly) or 18 (if you exercise five days or more a week). The number you’ll be left with is a rough idea of how many calories you’re most likely eating right now.

For example, if you weigh 165 pounds and exercise three days a week, then you would multiply 165 by 15 for a total of 2,475. That means your daily calorie intake—and how you will stay stuck at your current weight—is about 2,475 calories.

Step 2:

Reduce your daily calorie intake by between 500 to 1,000 calories. You can create this calorie deficit one of three ways:

1. You can eat 500 to 1,000 fewer calories each day.

2. You can burn off 500 to 1,000 calories each day through exercise.

3. You can combine a little of both, eating 250 to 500 fewer calories while burning 250 to 500 calories each day, for example.

Why not more? Most experts agree that losing between 1 and 2 pounds weekly is a safer, sounder approach to weight loss. Since 1 pound of fat equals approximately 3,500 calories, by reducing your caloric intake by 3,500 to 7,000 calories each week, you’ll safely lose about 1 to 2 pounds each week.

Keep in mind: Your daily calorie intake—the calories you eat—should never dip below 1,200 (for women) or 1,800 (for men). Eating any less than that can rob your body of the nutrients it needs to be healthy. To be sure you’re reaching your ideal calorie intake, consider using a free tracking tool, like MyFitnessPal. Through the website or app, you can easily record exactly what you eat each day. And because you can search and add specific foods and serving sizes (a cup of low-fat Greek yogurt, for example) all the work of counting is done for you, making tracking super simple.

Step 3:

Remember that anything can be exercise. If you hate running or weight training, there are plenty of other options that can help melt away body fat. Here are just a few ways to burn 100 calories (based on a 150-pound person).

• Swimming or taking a cardio dance class for 15 minutes (moderate intensity)

• Walking (at a pace of 3.5 miles per hour), shooting hoops, mowing the lawn, or painting a room for 20 minutes

• Casual biking or playing with your children for 23 minutes

Step 4:

Repeat step 1 every week to discover your new daily calorie intake. That may sound obvious, but a lot of people tend to follow the same diet plan for months—even years—then wonder why they never seem to lose weight. They forget that after their body becomes 1 or 2 pounds lighter, it doesn’t need as many calories to sustain that new weight. But by using the formula every week, you’ll always know exactly how much you should be eating to reach your goal and never hit a plateau.

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