STEP 1 Calculate your BMR 计算你的基础代谢率

Calculate your basal metabolic rate – the daily number of calories your body needs to function. For women, the formula is 655 plus 4.3 times your weight in pounds plus 4.7 times your height in inches, minus 4.7 times your age. For men, start with 66, add 6.3 times your weight, plus 12.9 times your height, minus 6.8 times your age.

If you have internet access, type "basal metabolic rate" into a search engine to find a BMR calculator that will find your number for you.

STEP 2 Factor in your activity 讲话你的活动率列入影响因素

Factor in the calories you burn daily. If you're sedentary, multiply your BMR by 20 percent; lightly active – 30 percent; moderately, 40 percent; very active, 50 percent; and extra active, 60 percent. Then add this number to your BMR. This is the daily calorie intake that will allow you to maintain your weight.

Moderate activity is defined by exercising nearly every day; very active means you exercise intensely daily; extra active refers to athletes and people engaged in hard labor.

STEP 3 Keep track of calories 时刻关注热量

Count the calories you consume by reading nutrition labels, looking up the calorie counts of non-packaged foods, and learning portion sizes for the foods you eat most often. Search online for calorie counts for fresh foods, name-brand items, and fast food. Check the percentage of calories that come from fat, even in so-called "diet foods."

Wear a pedometer to calculate the energy you expend walking.

STEP 4 Be careful in restaurants 小心餐厅

Tread carefully in restaurants, where it's often difficult to estimate calories. Stick with grilled, baked, and steamed foods, and watch portion sizes. Remove the temptation of some empty carbs by asking the waiter not to bring a bread basket.

STEP 5 Know the calories in one pound 知道一磅的热量

Understand the pound exchange. You have to burn 3,500 calories more than you consume to lose one pound of body weight.

STEP 6 Write it down 做记录

Write down everything you eat and its calorie count to help you stay on track. Good luck!

Most people who try to guess the calories in the food they're eating lowball them by as much as 45 percent!