It’s hard to lose weight if you don’t understand how it works.
Understanding the simple math behind weight loss can help you create a successful diet and exercise plan. So how does weight loss really work? It’s all about the numbers.
Calories burned per day
The human body burns calories all the time, even when we’re sleeping, simply by performing bodily functions like breathing. The number of calories you burn a day just by doing nothing is your Basal Metabolic Rate, or BMR. To find out your BMR, use this online tool or follow the equations below:
Women: BMR = 655 + (4.35 x weight in lbs) + (4.7 x height in inches) – (4.7 x age in yrs)
Men: BMR = 66 + (6.23 x weight in lbs) + (12.7 x height in inches) – (6.8 x age in yrs)
Here’s an example. Let’s say Sally is a 40-year-old woman who is 5’6” and weighs 150 pounds. That means that by doing nothing all day, she burns about 1,430 calories.
655 + (4.35 x 150) + (4.7 x 66) – (4.7 x 40) = 1429.7
However, most of us do more than sit on the couch all day, so you need to figure out how many additional calories you burn based on your lifestyle. To find out how many total calories you burn per day, use the formulas below in combination with your BMR:
Sedentary (little or no exercise) = BMR x 1.2
Lightly active (light exercise/sports 1-3 days/week) = BMR x 1.375
Moderately active (moderate exercise/sports 3-5 days/week) = BMR x 1.55
Very active (hard exercise/sports 6-7 days a week) = BMR x 1.725
Extra active (very hard exercise/sports & physical job or 2x training) = BMR x 1.9
If Sally leads a lightly active lifestyle, she would burn about 1966 calories per day. If she also follows a typical 2000 calorie-per-day diet, she would be burning roughly the same amount of calories that she’s consuming, meaning her weight would stay consistent.
So how can you use this information to lose weight?
Calories burned > calories consumed
To lose weight, you need to consume fewer calories than you burn. Now that you know how many calories you burn each day, you need to find out how many you consume each day to figure out the difference. There are many online tools like MyFitnessPal.com that can help you track your eating habits and count calories.
A healthy weight-loss rate is 1-2 pounds per week. One pound of stored body fat has about 3500 calories, so to lose 1-2 pounds you need to consume 3500-7000 less calories than you burn. Spread over the course of a week, that equals a 500-1000 calorie deficit per day.
The best way to do this is a combination of diet and exercise. You can cut calories from your diet, but make sure you’re still eating a sufficient amount. The American College of Sports Medicine recommends that daily calorie intake does not go below 1200 for women and 1800 for men. You should also add exercise to your daily routine to burn extra calories and help achieve your desired calorie deficit.
Looking at our example, if Sally wants to lose one pound per week, she needs to create a 500 calorie deficit each day. One way to do this would be to cut her diet to 1700 calories and increase her exercise to burn an additional 200 calories. She will be consuming 1700 calories a day and burning 2200, creating a 500 calorie deficit and allowing her to lose roughly one pound per week.
These same rules can be applied to those who might want to gain weight. Find out how many calories you burn per day, how many calories you’re currently consuming, and then adjust your diet and exercise habits to consume 500-1000 more calories than you burn each day.
Please Note: You should always consult your physician before beginning a weight loss program.