Macronutrients - Carbohydrates, Fats & Protein
Nutritionists often refer to carbohydrates, fats and proteins as macronutrients and vitamins and minerals as micronutrients. We require a relatively small amount of the micronutrients, and they have no caloric content. The macronutrients do have a caloric content with fats having the highest caloric density. So, of the three, fat is the most efficient storehouse for energy.
Macronutrient |
Calories Per Gram |
USDA Daily % Caloric Recommendation |
Carbohydrate |
4 |
45% - 65% |
Fat |
9 |
20% - 35% |
Protein |
4 |
10% - 35% |
Carbohydrates are classified as simple or complex. The simple sugars are smaller and include glucose and fructose. Since they are smaller molecules they get absorbed from the gastrointestinal tract very quickly. Glucose is the only source of energy used by the brain, so the body has several mechanisms to convert the other macronutrients into glucose if the glucose level is running low. Complex carbohydrates are actually simple carbohydrates linked together. They include corn, beans, root vegetables (potatoes), pasta & grains. Because they are larger, extracting energy from them takes a bit longer than from simple carbohydrates, but it is still relatively rapid. The body stores only about one day's worth of energy as carbohydrate in the form of glycogen in the liver and muscle.
Fats are made up of glycerol and fatty acids and due to this complexity, take the longest to release their energy. Since they hold the most energy per gram of any other macronutrient, the body stores most of its excess energy as fat. In addition, fats are important components of the walls of cells and other structures of the body.
Fats are classified by the degree of "saturation" of their chemical bonds. Those likely to raise levels of the bad cholesterol, LDL, are the saturated and trans fats. Therefore, you should try to eat more monounsaturated and polyunsaturated fats and avoid trans-fats and saturated fats.
Proteins are made up of chains of amino acids and are literally the building blocks of the body and form the enzymes & hormones that control its chemical reactions. Proteins are found in meat, poultry, fish, meat substitutes, cheese, milk, legumes, nuts and in smaller quantities in starchy foods and vegetables. The body breaks proteins down into their amino acids to reuse them. The body can make most of the amino acids it needs from other substances, but there are some, the essential amino acids, that it must get from food. All the necessary essential amino acids can be obtained from meat protein. However, not all the essential amino acids can be found in plant protein. When a person increases their amount of exercise it is important that they have enough protein to build muscle and prevent its breakdown. Many people ordinarily eat inadequate amounts of protein, so they either need to eat more protein-rich foods or take protein supplements.
The Food Pyramid
Until recently, the National Institute of Health (NIH) had talked about a practical system to help Americans eat healthier which they call the Food Pyramid. They divided foods into six Food Groups and recommended the number of daily servings for each of the Food Groups. The macronutrients we described above are contained within these Food Groups. The following table was taken from the NIH website. The Food Pyramid approach has been replaced by the MyPlate concept which is explained below. However, an understanding of serving size is key to healthy nutrition and this information based on the Food Pyramid helps define appropriate serving sizes.
| Food Group |
Daily Servings For 2000 Calorie Meal Plan |
| Grains |
6 - 8 |
| Vegetables |
4 - 5 |
| Fruits |
4 - 5 |
| Fat-free or low fat milk and equivalent milk products |
2 - 3 |
| Lean meats, poultry and fish |
2 or less |
| Nuts, seeds and legumes |
4 - 5 per week |
Just How Much Is A Serving?
The key to this approach is learning exactly how large a serving is for each of these. This next table gives you some examples for each Food Group.
| Food Group |
1 Serving |
| Grains |
1 slice bread
1 oz dry cereal
1/2 cup cooked rice, pasta, or cereal |
| Vegetables |
1 cup raw leafy vegetable
1/2 cup cut-up raw or cooked vegetable
1/2 cup vegetable juice |
| Fruits |
½ cup fruit juice
1 medium fruit
¼ cup dried fruit
½ cup fresh, frozen, or canned fruit |
| Fat-free or low fat milk and equivalent milk products |
1 cup fat-free or low-fat milk
1 cup fat-free or low-fat yogurt
1½ oz fat-free, low-fat, or reduced fat cheese |
| Lean meats, poultry and fish |
3 oz cooked meat, poultry, or fish (1 oz meat = 1 egg) (Limit egg yolk intake to no more than 4 per week due to high cholesterol in yolks.) |
| Nuts, seeds and legumes |
⅓ cup or 1½ oz nuts
2 Tbsp peanut butter
2 Tbsp or ½ oz seeds
½ cup cooked dry beans or peas |
ChooseMyPlate.gov
Recently the United States Department of Agriculture (USDA) replaced the Food Pyramid system with this easier approach to help people more easily focus on these tips for healthy eating:
- Make half your plate fruits and vegetables
- Make at least half your grains whole grains
- Switch to fat-free or low-fat (1%) milk
- Enjoy your food, but eat less
- Avoid over-sized portions
- Drink water instead of sugary drinks
In the next module, we'll look at how to shop wisely to improve your meal plan and help you lose weight and stay healthy. In the meantime, use the Practice Tests to learn this information.