This cheat sheet covers the main nutrients that provide energy and the basic formulas used to estimate daily calorie needs. Students need it to understand how food choices connect to energy, growth, activity, and overall health. It gives a clear reference for reading nutrition labels, planning balanced meals, and comparing different activity levels.
The goal is not dieting, but learning how the body uses fuel.
Key Facts
- Carbohydrates provide 4 calories per gram, protein provides 4 calories per gram, and fat provides 9 calories per gram.
- Calories from a macronutrient can be found with calories = grams x calories per gram.
- Total daily energy expenditure, or TDEE, estimates daily calorie needs using TDEE = BMR x activity factor.
- Basal metabolic rate, or BMR, is the energy your body uses at rest for basic functions like breathing, circulation, and temperature control.
- A basic calorie balance rule is weight maintenance occurs when calories in are about equal to calories out over time.
- For many teens, balanced meals include a source of carbohydrate, protein, healthy fat, and fiber-rich fruits or vegetables.
- Macronutrient percentages can be estimated with percent of calories = macro calories ÷ total calories x 100.
- Nutrition labels usually list serving size first, so all calories and macronutrient grams must be multiplied if you eat more than one serving.
Vocabulary
- Calorie
- A calorie is a unit of energy that describes how much energy food provides to the body.
- Macronutrient
- A macronutrient is a nutrient needed in large amounts that provides energy, mainly carbohydrates, protein, and fat.
- BMR
- BMR, or basal metabolic rate, is the amount of energy the body uses at rest to support basic life functions.
- TDEE
- TDEE, or total daily energy expenditure, is an estimate of the total calories a person uses in one day.
- Activity Factor
- An activity factor is a number used to adjust BMR based on how much physical activity a person does.
- Calorie Balance
- Calorie balance is the relationship between calories consumed from food and calories used by the body.
Common Mistakes to Avoid
- Ignoring serving size is a mistake because the listed calories and macronutrients apply only to one serving, not always the whole package.
- Treating all calories as nutritionally equal is a mistake because foods with similar calories can differ greatly in vitamins, minerals, fiber, and protein.
- Using BMR as total daily calorie needs is a mistake because BMR does not include energy used for walking, exercise, digestion, or daily activities.
- Cutting out an entire macronutrient group is a mistake because carbohydrates, protein, and fats each support different body functions.
- Assuming one calorie target fits everyone is a mistake because age, body size, activity level, growth, sleep, and health needs can all change energy needs.
Practice Questions
- 1 A snack has 30 g of carbohydrates, 8 g of protein, and 10 g of fat. How many total calories come from these macronutrients?
- 2 A student has an estimated BMR of 1,500 calories and an activity factor of 1.6. Estimate the student's TDEE using TDEE = BMR x activity factor.
- 3 A meal has 600 calories total, with 180 calories from protein. What percent of the meal's calories come from protein?
- 4 Why is TDEE usually a better estimate than BMR for planning daily calorie needs?