When it comes to healthy eating, there are many factors to consider, including whether or not to eat organic or vegetarian, considering fads such as the paleo and ketogenic diets, and counting nutritional facts such as fat grams, carbohydrates and protein. But one health indicator that has been monitored for years and years is calories.
Calories aren’t necessarily bad for you. After all, your body needs calories for energy. Most foods and drinks contain calories, which are a unit of energy that measure how much energy your body could get from eating or drinking something. But too many calories — and not burning enough off calories through activity — can lead to weight gain.
How Many Calories Do You Need?
Knowing how many calories you should to consume each day is essential for maintaining, losing or gaining weight. On average, a woman needs to eat about 2,000 calories per day to maintain her weight, and 1,500 calories per day to lose one pound of weight per week. Likewise, an average man needs 2,500 calories to maintain his weight, and 2,000 to lose one pound of weight per week. However, these numbers depend on numerous factors, including age, height, your current weight, your activity levels, metabolic health and more.
A single gram of a carbohydrate or protein only provides four calories. But if you eat high-fat or high-carb foods, the overall calorie cost will be high.
Calculating the Calories You Burn
The Harris-Benedict formula can determine your basal metabolic rate (BMR), which is also called the resting energy expenditure. It tells you how many calories you burn just by being alive and awake. However, since you most likely move around every day, you can determine your active metabolic rate (AMR) by multiplying your BMR by a number that best represents your current activity levels. This number ranges from 1.2 for being sedentary, up to 1.9 for being extra active.
Here are the calculations to determine your BMR:
- Women: BMR = 655 + (4.35 x weight in pounds) + (4.7 x height in inches) – (4.7 x age in years)
Men: BMR = 66 + (6.23 x weight in pounds) + (12.7 x height in inches) – (6.8 x age in years)
For women in the United States, the average BMR is 1,493 calories. For American men, the average BMR is 1,662 calories.
Then use these numbers to find your AMR:
- Sedentary (little or no exercise): your AMR = BMR x 1.2
- Lightly active (light exercise/work 1-3 days per week): your AMR = BMR x 1.375
- Moderately active (moderate exercise/work 3-5 days per week): your AMR = BMR x 1.55
- Very active (hard exercise/work 6-7 days a week): your AMR = BMR x 1.725
- Extra active (very hard exercise/work 6-7 days a week): your AMR = BMR x 1.9
AMR represents the total amount of calories you expend through the day. With regard to calories, AMR also represents the number of calories you need to consume each day to stay at your current weight. If your goal is to lose weight, you need to increase your level of physical activity and/or decrease the amount of calories you eat each day.
The the Harris-Benedict formula isn’t perfect, and research studies from the Academy of Nutrition and Dietetics say the formula is 90 percent accurate 60 percent of the time, which means it could be off as much as 40 percent of the time. But it’s still a good place to start.