Contents
Nutrition Fundamentals
How to Understand Calories
How to Understand Nutrients
The Right Balance of Nutrients
The Food Groups
How to Eat a Nutritious Diet Based on the Food Groups
Functional Foods
Healthy Eating at Home
How to Read Nutrition Labels
Healthy Eating Away from Home
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How to Understand Calories
Good nutrition means maintaining a healthy body weight by balancing the number of calories you consume with the number of calories you burn. If you burn more calories than you consume, you’ll lose weight; if you consume more than you burn, you’ll gain weight. If you eat just the right amount, you’ll maintain the same weight. So the first step toward improving your nutrition is figuring out how many calories you need daily.
How Many Calories Do You Need?
The number of calories you should consume depends primarily on your activity level. There are three basic levels of activity into which most people fit:
- Sedentary: Little or no exercise
- Active: 30–60 minutes of exercise a day
- Very active: More than 60 minutes of exercise a day
The table below provides rough guidelines for daily caloric intake based on your sex and activity level.
Sex |
Activity Level |
Calories Needed |
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Male |
Sedentary |
2,400 per day |
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Active |
2,800 per day |
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Very active |
3,000 per day |
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Female |
Sedentary |
2,000 per day |
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Active |
2,200 per day |
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Very active |
2,400 per day |
To get an even more precise measure of your caloric needs, you can use a tool called the Harris Benedict Formula.
The Harris Benedict Formula
The Harris Benedict formula uses your weight, height, age, and sex to determine your basal metabolic rate (BMR), a measure of how many calories you would burn if you slept all day long. You can then calculate your ideal caloric intake by multiplying your BMR by a number based on your activity level.
The Harris Benedict Formula uses weight measured in kilograms (kg) and height measured in centimeters (cm). To convert your weight from pounds to kilograms, multiply by 0.4536. To convert your height from inches to centimeters, multiply by 2.54.
Using the Harris Benedict Formula
The Harris Benedict formula first calculates your BMR:
- For men: BMR = 66 + (13.7 × weight in kg) + (5 × height in cm) – (6.8 × age in years)
- For women: BMR = 655 + (9.6 × weight in kg) + (1.8 × height in cm) – (4.7 × age in years)
Once you’ve calculated your BMR, multiply it by your activity factor:
- Sedentary: BMR × 1.2
- Active: BMR × 1.55
- Very active: BMR × 1.725
Using the Harris Benedict formula, an active 30-year-old woman who weighs 52 kg (115 lbs) and is 165 cm (5'5") tall would need to consume:
- BMR = 655 + (9.6 × 52) + (1.8 × 165) – (4.7 × 30) = 1,310.2
- Daily calories needed = 1,310.2 × 1.55 = 2,030.81
How Many Calories Do You Eat?
To figure out how many calories you typically consume over the course of one day:
- Write down the types and amounts of all the foods you eat during a typical day (include foods you use to cook with, such as oils and butter).
- Look up the foods in a calorie counter, a book or online database that lists the calorie content for different foods.
- Add up the calories.
If the calories you eat during an average day are significantly higher or lower than the calories that the Harris Benedict formula indicates you need, consider altering your diet.
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