What is Macronutrient?
Macronutrients (carbohydrates, proteins, and fats) provide energy for daily activities and during exercise, recreational activity, and sport training. They provide slightly different numbers of calories per gram, as follows:
- Carbohydrates provide about 4 calories per gram.
- Proteins provide about 4 calories per gram.
- Fats provide about 9 calories per gram.
These values show clearly that on a gram per gram basis, fat is much denser with regard to calories than carbohydrate or protein. This is the reason a food high in fat provides more calories than a food lower in fat. Chapter 18 provides additional information on the macronutrients as they pertain to weight management. Although alcohol is not a required nutrient, it has its own unique calorie content of 7 calories per gram.
Although some diets (e.g., the Atkins diet) seem to suggest that carbohydrates are the villain when it comes to weight management, carbohydrates are actually vital for the optimal functioning of your body. For example, your brain and central nervous system rely on carbohydrate or glucose in the blood for energy. Carbohydrates are also an important source of energy during physical activity. Without sufficient carbohydrate in your diet, you will not be able to fully enjoy a vigorous workout or competition because your body will not have the fuel it needs to perform.
Carbohydrates in Food
Carbohydrates exist in the form of sugars, starches, and fiber. Sugars are naturally found in items such as fruit and milk products. Sugar is also added to various products for flavor and taste. Cutting down on products with added sugar is recommended (e.g., candy, nondiet soda, and fruit drinks). These are rather obvious, but checking food labels can reveal added sugars that aren’t as obvious. When searching for added sugars in foods, first check the ingredients list. Added sugars can be identified by many different names, including brown sugar, corn sweetener, corn syrup, dextrose, high-fructose corn syrup, glucose, honey, lactose, maltose, malt syrup, molasses, and sucrose. Be especially careful when these items are listed among the first few ingredients on the food label because components are listed in the order of predominance by weight.
Based on the 2015 Dietary Guidelines for Americans, the recommendation is to limit calories from added sugars to 10 percent per day. Focusing on fruits, vegetables, and whole-grain products maximizes the health benefits of carbohydrates. Starches are a more complex form of carbohydrate that the body can use for energy and are found in products such as vegetables, dried beans, and grains. Starches are different from sugars because they are chemically composed of long chains of sugars linked together. Consumption of whole grains can help prevent cardiovascular disease, type 2 diabetes, and other chronic diseases mainly because they are high in vitamins and minerals, as well as antioxidants. More information on disease prevention appears in part IV of this book. The third category of carbohydrate—fiber—includes parts of food that the body cannot break down and absorb. Sources of fiber include vegetables, fruits, and whole grains. Consuming higher-fiber foods promotes greater feelings of fullness as well as bowel health. Higher-fiber diets have been found to reduce the risk of diabetes, colon cancer, and obesity.
Sources of Carbohydrates
The above figure provides examples of good sources of carbohydrates, including the contribution made by fiber.
Calories From Carbohydrates
Approximately 45 to 65 percent of your calorie intake should be from carbohydrates. This is a relatively wide range to account for the variety of nutritional approaches while avoiding deficiencies or adverse health consequences. Out of this 45 to 65 percent, strive to consume a variety of these types of carbohydrates. Typical diets tend to over consume the simple sugars and under consume starches and fiber. The Daily Value listed on food labels is based on 60 percent of the calorie intake. If you are active, or if you are a competitive athlete, keeping your carbohydrate intake near the upper end of this range provides sufficient fuel for your working muscles. Now that you know about how many calories you need per day, as figured from figure 1 you can determine how much carbohydrate is recommended. For example, for someone who needs 2,500 calories per day, approximately 1,125 to 1,625 calories should be from carbohydrate. This would be calculated as follows:
2,500 calories per day 0.45 (45%) = 1,125 calories from carbohydrate
2,500 calories per day 0.65 (65%) = 1,625 calories from carbohydrate
To determine the number of grams of carbohydrate you need, recall that each gram of carbohydrate supplies 4 calories. Simply take the number of calories from carbohydrate and divide by 4 to determine how many grams you need:
1,125 calories / 4 calories per gram = 281 grams from carbohydrate
1,625 calories / 4 calories per gram = 406 grams from carbohydrate
Protein is another important macronutrient needed for your body. Proteins are made of small units called amino acids, which are considered the building blocks of the body. Proteins promote muscle growth and are required for many body functions, including assistance with chemical reactions and hormones. Even though proteins can provide 4 calories per gram, you typically do not use protein for energy unless you are deficient in your intake of carbohydrate or fat. This is so the protein you consume can be used to promote growth and for normal body functions.
Calories From Proteins
Proteins should account for about 10 to 15 percent of total calories (AMDR is 10 to 35 percent for adults). As with carbohydrates, a range is provided to account for differences in diet and to suggest a safe upper limit. Depending on your total calorie intake, you may be near the low or high end of this range. Your personal protein requirement is based on your body weight; you should consume approximately 0.36 grams of protein for each pound of body weight. Simply multiply your body weight in pounds by 0.36 to determine approximately how many grams of protein you need to consume each day. If you know your body weight in kilograms, multiply that value by 0.8. For example, for a 150-pound or a 68-kilogram person, this would be figured as shown:
150 pounds x 0.36 = 54 grams protein x 4 calories/gram = 216 calories from protein
68 kilograms x 0.8 = 54 grams protein x 4 calories/gram = 216 calories from protein
Things To Remember
Note that protein requirements are increased for athletes and are different depending on the sport, the intensity and frequency of the workout, and how experienced the athlete is. Typical recommendations for strength-trained athletes (e.g., American football players, bodybuilders) and endurance athletes (e.g., marathon runners) are between 0.55 and 0.77 grams of protein per pound of body weight (or 1.2 to 1.7 grams of protein per kilogram of body weight). Because many Americans already consume more than the Recommended Dietary Allowance for protein, athletes or other highly active people may already be consuming adequate protein. For those with inadequate intake, increased focus on consuming a variety of protein foods is recommended.
Do protein requirements change with age?
It is often believed that as individuals age, protein needs change. This is not necessarily true for the average healthy adult. The Dietary Reference Intakes recommend that adult males consume 56 grams of protein per day and adult females consume 46 grams of protein per day, regardless of their age. It is important to remember that these numbers are general guidelines for the average individual. Protein needs always vary depending upon the individual.
Fat is another vital macronutrient needed for your body. Fats, also called lipids, are provided in the diet from such sources as animal protein, butter, oils, nuts, and many refined products. Fats are often thought of as bad, a myth perpetuated by the many fat-free products flooding store shelves. However, fats are needed in appropriate amounts for normal functioning in the body. For example, lipids are the main component of each cell in your body. In addition, fat is a major source of energy, especially when you are at rest or performing low- to moderate intensity physical activity. Excessive consumption of fat is unhealthy, but concerns also arise when fat intake is too low. A balanced approach to fat intake provides the necessary amount of fat for optimal health.
Forms of Fat
Fats are present in a number of forms, including saturated fats, monounsaturated fats, and polyunsaturated fats. These designations have to do with the chemical structure of the fat. Trans fats are found naturally in some animal products (mainly meat and dairy products), but also are a result of a manufacturing process called hydrogenation. Hydrogenation changes the structure of a fat to make it more stable and as a result more like saturated fats (which are solid at room temperature). Food companies hydrogenate fat to increase the shelf life of the product, to make it taste more like butter, and to save money because it is less expensive to hydrogenate oil than it is to use butter. In general, health concerns result from consuming too much saturated and trans fats.
Trans fats have been shown to increase the “bad” cholesterol in blood (low-density lipoprotein cholesterol, or LDL-C), even more so than saturated fats. Sources of trans fats include animal products, margarine, and snack foods. The good news is that as a result of health concerns, the food industry is reformulating many products to remove or at least reduce the amount of trans fat. Many restaurants have also now gone “trans fat free.” Companies that make processed food products are required to list the amount of trans fat in their products. Although some products have labels that state they are “trans fat free,” this actually means that they contain no more than 0.5 percent trans fat.
Monounsaturated fats, such as olive oil, canola oil, avocados, walnuts, and flax-seeds, have been shown to be protective against heart disease and type 2 diabetes mellitus. That is not to say that you can consume as much monounsaturated fat as you want; however, selecting monounsaturated fats instead of saturated fats may lead to better health (e.g., healthier blood cholesterol levels). Polyunsaturated fats, such as safflower oil, corn oil, and fish oils, have also been shown to be protective against many diseases.
Fish oils (eicosapentaenoic [EPA] and docosahexaenoic [DHA]) have been shown to decrease inflammation within the body and may protect against heart disease, type 2 diabetes, and arthritis. This does not mean that EPA and DHA are protective against everything, but they are important to overall health. Therefore, you should try to consume 2 to 3 ounces (56 to 85 g) of fatty fish (e.g., tuna, salmon, and sardines) at least two days per week. Fish oil supplements may also be warranted (consult with your health care provider to see if this is appropriate for you). Saturated fats are found in products such as butter, cheese, meat, palm oil, and whole milk.
Do you blame Fat?
Because of the increased risk of disease associated with saturated fats, less than 10 percent of your calories should come from saturated fats, with an even better target of less than 7 percent. Trans fats also should be limited to as little as possible. Because of the focus on saturated and trans fats, the nutrition labels on food products include total fat as well as the amount of saturated and trans fats. Although not technically a fat, cholesterol is in the lipid family and is found in animal products. Your body needs a certain amount of cholesterol; thus, even if your diet contained none, the liver would produce what your body needs. The problem arises when cholesterol levels in the blood become too high. Total blood cholesterol levels, as well as LDL-C levels, are predictors of heart disease. Although you consume cholesterol in your diet, a major factor influencing your blood cholesterol levels is the amount of saturated and trans fats you consume. Thus, limiting saturated fat intake to no more than 10 percent of your calories is recommended (no more than 7 percent is even better).
Calories and Fat
Total fat intake should be between 20 and 35 percent of calories. Most of these calories should come from monounsaturated and polyunsaturated fats (e.g., fish, nuts, vegetable oils), and your consumption of saturated fat should be limited. For example, for someone with a target of 2,500 calories per day, total fat intake should be between 20 and 35 percent of total calories. In this example, a target of 28 percent is selected (middle of the range). This would be approximately 700 calories from fat and would be calculated as follows:
2,500 x 0.28 = 700 calories
To keep saturated fat at no more than 10 percent of total calories, the calories from saturated fat would total only 250, determined as follows:
2,500 x 0.10 = 250 calories from saturated fat
To determine how many grams this represents, the calories from fat can be divided by 9 (recall that each gram of fat provides 9 calories). Thus, in this example, total fat would be around 78 grams (700 / 9 = 78), and saturated fat would be no more than around 28 grams (250 / 9 = 28).
Some of the food groups contributing to saturated fat intake are cheese, beef, milk products, frozen desserts, snack foods (e.g., cookies, cakes, doughnuts, potato chips), butter, salad dressings, and eggs. Making small changes in the foods you select could result in meaningful decreases in the saturated fat and calories you consume. See the above figure 3 for some comparisons between higher- and lower-fat food selections.