Macronutrients, including proteins, carbohydrates, and lipids, are the building blocks of diet. Patients, families, and physicians need to understand macronutrients to craft themselves a diet that will be delicious, nutritious, inexpensive, easy to prepare, and acceptable to others with whom they eat.
By Mark D. Harris
Look down the street on a busy day. In the US, on average, nearly three out of every four people you see will be overweight (body mass index 25-30) or obese (BMI 30+). More than 70% of young adults are too unfit to serve in the military due to their weight. Black and Hispanic Americans are more likely to be obese and overweight than white or Asian Americans. Everyone, from individuals to families to health care providers, must engage to fix this problem. Understanding macronutrients is a start.
- What are macronutrients?
A macronutrient is a nutrient that the human body needs in large amounts to attain and maintain good health. Macronutrients include protein, carbohydrate, and lipids (USDA, 2020).
- What do the US Department of Agriculture (USDA) and others recommend for healthy eating patterns for Americans of various ages in terms of macronutrients?
The USDA understands a dietary pattern as the totality of what an individual eats and drinks over an extended period, such as a life stage or lifespan (USDA, 2020). A healthy eating pattern is one that improves health and longevity. The USDA recognizes three healthy eating patterns, the Healthy Mediterranean Style Dietary Pattern, the Healthy Vegetarian Dietary Pattern, and the Healthy US-style Dietary Pattern. These patterns provide guidance on what kinds of food and drink, and how much, to consume on a given day (USDA, 2020).
A Mediterranean dietary pattern is rich in fish, olive oil, fruits, vegetables, grains, and legumes/nuts. Red meats, refined grains, and sugars are limited (Locke et al., 2018). For example, a Healthy Mediterranean style meal might use brown rice and avocado while a non-healthy style could use white rice and enriched guacamole instead. A vegetarian dietary pattern sticks with plant-based food, plant oils, nuts, seeds, legumes, fruits, and vegetables (Locke et al., 2018). Both decrease rates of type 2 diabetes, coronary artery disease, and obesity (Locke et al., 2018).
Healthy eating patterns will keep those who follow them within the recommended range of macronutrients. For people ages 2 and older, a good daily diet will include 25-34 grams of fiber, and 10-17 grams of linoleic acid. Added sugars must not exceed 10% of total calories (USDA, 2020). Protein, carbohydrate, and lipid levels are noted in Table 1 (USDA, 2020).
- Using tables or figures, how do the USDA, Mediterranean, Dietary Approaches to Stop Hypertension (DASH), and plant-based eating plans compare in terms of how much macronutrients are consumed?
| Table 1 | USDA | Mediterranean | DASH |
| Protein | 10-35 | 15 | 15 |
| Carbohydrate | 45-65 | 55-60 | 55-60 |
| Lipid | 25-35 | 20-30 | 20-30 |
- What is the USDA’s MyPlate Plan, and how does it differ from Canadian and other recommendations?
The US MyPlate Plan is intended to make healthy eating easier by subdividing a typical plate into four sections. Two sections, one-half of the total plate, should be fruits and vegetables, specifying whole fruits and varied vegetables (U.S. Department of Agriculture, 2020). One section, one-quarter of the plate, should be grains, preferably whole grains. The final quarter of the plate would be proteins, such as lean meats, beans, or nuts. Dairy, the cup to the right of the plate, ought to be fat free (U.S. Department of Agriculture, 2020). Avoiding processed food and making dessert infrequent contributes to health.
The US and Canadian MyPlate guidelines are similar, highlighting whole fruits and vegetables. Whole grains predominate and protein/dairy is limited. The Canadians specifically tell readers to make water their drink of choice. Notably, healthy eating is more than just food, and the Canadian MyPlate encourages people to be mindful of eating habits, cook more often, enjoy their food, eat meals with others, and use food labels (Government of Canada, 2019).
- What is the process by which these various guidelines are developed, and how have they changed over recent years? For example, how have guidelines shifted from a focus on individual foods and macronutrients to patterns of eating?
The USDA Dietary guidelines were developed by a team of scientists following a four-step process (USDA, 2020). First, the team identified pertinent topics and formed applicable scientific questions based on those topics. An example topic might be macronutrients and the questions might be how much fat should a male between ages 30 and 40 consume per day. In the second step, the guideline team reviewed current scientific evidence (USDA, 2020). When Federal and other data was available, they analyzed the data. They also searched for high quality systematic scientific reviews. The team modeled health outcomes that would occur if high percentages of people followed the guidelines.
The third step in developing the guidelines involved using the information gathered to write the actual guidelines. Fourth, the investigation team implemented these guidelines (USDA, 2020). The MyPlate communication plan is part of the implementation.
- What are some of the limitations and common criticisms of the USDA guidelines?
The USDA guidelines are guidance on foods, highlighting which foods and healthy eating patterns contribute most to well-being. These guidelines do not cover nutrient requirements, which describe how much of which nutrients are needed for optimal body function. Nutrient requirements are set by the National Academies of Science, Engineering, and Medicine (USDA, 2020).
Furthermore, USDA guidelines are intended to promote health, not treat disease. A patient with diabetes or kidney failure may need a slightly different diet than what is recommended in these guidelines. A patient, in concert with his or her health care team, may make changes to any of these healthy eating plans. Another limitation is the varying quality of the scientific evidence base.
- What is the Healthy Eating Index? How does the average American eating pattern compare with guideline-directed eating?
The healthy eating index measures the average compliance of the US population with the USDA dietary guidelines, ranging from perfect (score 100) to none (score 0) (USDA, 2020). The average score in 2015 was 59, ranging from 51 in the 14-18 age group to 63 in the 60+ age group.
- What is the association between the adoption of and adherence to healthy eating guidelines and improved health?
Consistently following the healthy eating guidelines is associated with a wide variety of improved health outcomes. In the first two years of life, children whose parents follow such guidelines enjoy a lower risk of overweight and obesity, reduced incidence of Type 1 diabetes, and lower risks of iron deficiency, peanut allergy, and asthma (USDA, 2020). During childhood, adhering to healthy eating contributes to lower adiposity and improved cholesterol levels. Women who are pregnant or nursing and follow the USDA dietary practices will improve cognitive development in their child and better folate status for themselves.
Adults receive the greatest benefits. All-cause mortality decreases, as does cardiovascular disease and mortality. Cholesterol decreases, blood pressure improves, and the risk of obesity declines. Breast, colon, and rectal cancers and type 2 diabetes become less likely (USDA, 2020). Bones get healthier, and the risk of hip fracture diminishes.
- What is the recommended overall caloric intake for individuals of various stages of life? How should caloric requirements and goals for consumption be estimated? What online tools are most reliable and useful for patients? How does caloric intake relate to energy expenditure?
Calorie needs for school aged children range from 1200 (sedentary 5-year-old) to 2400 (active 12-year-old male) (USDA, 2020). Teenage requirements go from 1600 (sedentary 13-year-old female) to 3200 (active 18-year-old male). Adults over 19 will need from 1600 (sedentary 76-year-old female) to 3000 (active 20-year-old male). Pregnancy increases caloric requirements by 300-400 per day (USDA, 2020). Such need estimates are based on Estimated Energy Requirements, which consider reference heights and weights for each age and sex group. The Dietary Reference Intake (DRI) is a good online tool. Caloric intake should equal energy expenditure on a given day.
- What foods are preferred sources for proteins, fats, and carbohydrates? What food sources (eg, refined sugars, saturated fats) should be limited or avoided, and why? What limits are recommended, and are there risks to exceeding or being far below those limits?
Nutrient dense foods are preferred for proteins, fats, and carbohydrates. Fresh, frozen, or canned vegetables with color – green, red, and orange – add dash to the look of a plate and enliven the body (USDA, 2020). Fiber and carbohydrates are plentiful. Fruits, fresh, frozen, canned, and dried, make up another good source of carbohydrates and fiber. Proteins and fats most commonly occur in animal products (meat, poultry, eggs, dairy, seafood) and nuts, seeds, or soy products (USDA, 2020).
Refined sugars and saturated fats are calorie rich but nutrient poor, so should be avoided or at least minimized. Added sugars should not comprise more than 10% of total calories per day.
- What is important about the type, source, and quality of macronutrients as opposed to simply their amounts?
The source of macronutrients, not only their presence and amounts, is an important consideration in a good diet. Alcohol provides energy in the form of carbohydrates, for example, but otherwise has little nutritional value (Dietary Guidelines Advisory Committee., 2020). The best macronutrient sources provide carbohydrates, unsaturated fats, proteins, and micronutrients including vitamins and minerals (USDA, 2020).
In another study, consumption of processed meat, red meat, and poultry was associated with a higher risk of cardiovascular disease (Zhong et al., 2020). The same study also found that processed meat and unprocessed red meat, but not poultry or fish, was associated with an increased risk of all-cause mortality. This suggests that poultry and fish are healthier sources of animal proteins (macronutrient) than red or processed meat.
- What are processed and ultra-processed foods? Are they harmful? Why or why not?
The US Department of Agriculture defines processed foods as (The Nutrition Source & Harvard School of Public Health, 2019):
A processed food is one that has undergone any changes to its natural state—that is, any raw agricultural commodity subjected to washing, cleaning, milling, cutting, chopping, heating, pasteurizing, blanching, cooking, canning, freezing, drying, dehydrating, mixing, packaging, or other procedures that alter the food from its natural state. The food may include the addition of other ingredients such as preservatives, flavors, nutrients and other food additives or substances approved for use in food products, such as salt, sugars, and fats.
Examples of processed foods include meats (hot dogs, sausages, ham, lunch meats), certain cheeses, and certain soy products (USDA, 2020). The NOVA system categorizes foods based on their degree of processing (Braesco et al., 2022):
- NOVA 1 – unprocessed or minimally processed food, such as an apple, raw egg, or carrot.
- NOVA 2 – NOVA 1 foods with added culinary ingredients such as salt, oil, or sugar.
- NOVA 3 – NOVA 1 and 2 foods transformed into foods such as baked bread, canned vegetables, or cured meats.
- NOVA 4 – Ready to eat, formulated products derived from foods and additives with little NOVA 1 food remaining.
By the NOVA classification system, ultraprocessed foods would be in category 4. Processed and especially ultraprocessed foods have health hazards. often excessive amounts of sodium, conferring a risk to heart health. One prospective cohort study found that ultraprocessed foods increased cardiovascular, coronary heart, and cerebrovascular disease by 10% (Srour et al., 2019). Similar to Srour, Nilson et al. (2022) concludes that reducing ultraprocessed food consumption in adults by 10% would prevent approximately 11% of the premature CVD deaths.
- Does it matter whether protein is obtained from animal or plant sources? Why or why not? What is the role of protein supplements?
In one large cohort study, mortality in subjects who consumed plant protein was significantly lower than those who consumed egg or red meat protein (Ge et al., 2020). Das et al. (2021) found that animal protein consumption was positively and plant protein consumption negatively correlated with all-cause and cancer mortality. In the Rotterdam study and associated meta-analysis, Chen et al. (2020) discovered that higher protein intake, especially of animal proteins, was associated with higher all-cause mortality. Total plant protein was not associated with all-cause or cause specific mortality. A meta-analysis of other studies on this topic produced consistent findings (Chen et al., 2020). Huang et al. (2020) noted that replacing only 3% of animal with plant protein improves mortality. In summary, plant sources of protein are healthier than animal sources.
Dietary supplements may provide one or more nutrients that a person consumes in less than recommended amounts (USDA, 2020). However, such supplements are often of micronutrients such as folic acid during pregnancy or iron in young children. Protein supplements may adversely impact kidney and liver function and should be eschewed in favor of natural sources of protein (Vasconcelos et al., 2020).
- How can healthy eating be adapted to personal and cultural preferences and budgetary constraints? What is the role of consultants, such as registered dietitians, and when should they be consulted?
Many diets and discussions of nutrition focus on nutrients rather than on foods and can be ineffective in encouraging diet change (Locke et al., 2018). No diet has been proven superior to any other for weight loss, so the most important task is to find a diet that the patient will adhere to (Ge et al., 2020). Barriers to a healthy diet can be cultural, emotional eating, financial, insufficient knowledge, poor cues to satiety, and limited cooking skills (Locke et al., 2018).
In a pluralistic society, patients from a variety of backgrounds will need to adjust their diets to fit personal preferences, their culture, and their budget (USDA, 2020). Families should select nutrient dense, healthy food, and build a taste for these foods in their children from an early age. Spices and herbs help flavor food when reducing sugar, salt, and saturated fat (USDA, 2020). The USDA has a variety of food plans to help families whatever their budget.
Family physicians can refer to dieticians and other consultants to advise patients about healthy eating. This is especially true in patients with chronic medical conditions who need personally tailored recommendations.
- What guidance can we give to patients regarding reading packaging labels and using smartphone apps to track caloric and macronutrient intake?
FPs should teach their patients to read food labels and to select packaged foods that are lower in saturated fats, milk that is low or no fat, low fat cheese and lean meat (USDA, 2020). Oils used for cooking should be higher in polyunsaturated and monounsaturated fat rather than butter, shortening, coconut, or palm oils (USDA, 2020). Reading food labels can allow for healthy and tasty menu substitutions (USDA, 2020).
Counseling about diet involves three parts (Campbell, 2022). First and most importantly, patients must carefully consider their food choices. High bulk and lower calorie foods make a person feel more sated than low bulk, high fat foods (Campbell, 2022). Eating structure, meaning when and under what conditions a person eats, must also be modified. Missing breakfast is associated with increased cardiovascular disease and all-cause mortality, but 20% of Americans do it anyway (Campbell, 2022). Structured mealtimes with family or others three times per day is associated with improved health in children and adolescents. Eating “comfort food” when stressed, excited, or bored will not help achieve dietary goals.
Smartphone applications such as MyFitnessPal, LoseIt, FatSecret, and Cronometer can be useful in helping modify a person’s diet (Campbell, 2022). MyFitnessPal is a food, exercise, and calorie tracker. LoseIt includes exercise and meal planning. FatSecret is free and is also a food diary and calorie counter. Cronometer includes these and other functionalities.
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