Protein, Carbohydrates and Fats

The McKinley Health Center  
Macronutrients: the Importance of Carbohydrate, Protein, and Fat
Why do we need carbohydrates to survive?

Carbohydrates are the macronutrient that we need in the largest amounts. According to the Dietary Reference Intakes published by the USDA, 45% - 65% of calories should come from carbohydrate. We need this amount of carbohydrate because:
• Carbohydrates are the body’s main source of fuel.
• Carbohydrates are easily used by the body for energy.
• All of the tissues and cells in our body can use glucose for energy.
• Carbohydrates are needed for the central nervous system, the kidneys, the brain, the muscles (including the
heart) to function properly.
• Carbohydrates can be stored in the muscles and liver and later used for energy.
• Carbohydrates are important in intestinal health and waste elimination.
• Carbohydrates are mainly found in starchy foods (like grain and potatoes), fruits, milk, and yogurt. Other
foods like vegetables, beans, nuts, seeds and cottage cheese contain carbohydrates, but in lesser amounts.

Fiber refers to certain types of carbohydrates that our body cannot digest. These carbohydrates pass through the intestinal tract intact and help to move waste out of the body. Diets that are low in fiber have been shown to cause problems such as constipation and hemorrhoids and to increase the risk for certain types of cancers such as colon cancer. Diets high in fiber; however, have been shown to decrease risks for heart disease, obesity, and they help lower cholesterol. Foods high in fiber include fruits, vegetables, and whole grain products.
Why do we need protein to survive?

 Protein is found in meats, poultry, fish, meat substitutes, cheese, milk, nuts, legumes, and in smaller quantities in starchy foods and vegetables.
When we eat these types of foods, our body breaks down the protein that they contain into amino acids (the building blocks of proteins). Some amino acids are essential which means that we need to get them from our diet, and others are nonessential which means that our body can make them. Protein that comes from animal sources contains all of the essential amino acids that we need. Plant sources of protein, on the other hand, do not contain all of the essential amino acids.

According to the Dietary Reference Intakes published by the USDA 10% - 35% of calories should come from protein. Most Americans get plenty of protein, and easily meet this need by consuming a balanced diet. We need protein for:
• Growth (especially important for children, teens, and pregnant women)
• Tissue repair
• Immune function
• Making essential hormones and enzymes
• Energy when carbohydrate is not available
• Preserving lean muscle mass

Why do we need fat to survive?

Fat is found in meat, poultry, nuts, milk products, butters and margarines, oils, lard, fish, grain products and salad dressings. There are three main types of fat, saturated fat, unsaturated fat, and trans fat. Saturated fat (found in foods like meat, butter, lard, and cream) and trans fat (found in baked goods, snack foods, fried foods, and margarines) have been shown to increase your risk for heart disease. Replacing saturated and trans fat your diet with unsaturated fat (found in foods like olive oil, avocados, nuts, and canola oil) has been shown decrease the risk of developing heart disease.

Although fats have received a bad reputation for causing weight gain, some fat is essential for survival. According to the Dietary Reference Intakes published by the 20% - 35% of calories should come from fat. We need this amount of fat for:
• Normal growth and development
• Energy (fat is the most concentrated source of energy)
• Absorbing certain vitamins ( like vitamins A, D, E, K, and carotenoids)
• Providing cushioning for the organs
• Maintaining cell membranes
• Providing taste, consistency, and stability to foods