Chapter 2: Guidelines for Healthy Eating

Learning Objectives

By the end of this chapter you will be able to:

• Describe qualities of high-quality food.
• Describe how Dietary Reference Intakes are determined and how they are used.
• Define and explain the uses of the six Dietary Reference Intakes.
• Discuss physical activity, sleep, drug use, and cultural influences as they interact with diet in a healthy lifestyle.
• Describe characteristics of healthy eating patterns.

Food Quality

Food quality or nutritional value are important concepts in the discussion of nutrition. Nutrient density is a measure of the nutrient content of a food relative to its energy content. High-quality foods are rich sources of vitamins, minerals, protein, healthy fats, and/or fiber in forms that are low in salt, sugar, and less-healthy fats. Examples include vegetables, fruits, whole grains, legumes such as kidney beans, lean meats and fish, and low-fat dairy foods.

Nutrient-dense foods are the opposite of “empty-calorie” foods such as carbonated soft drinks, salty chips, and sweet treats such as candy and cookies. These foods provide many calories but few other nutrients and are best included in diets as occasional treats only. The manufacturing of highly-processed foods strips the nutrients from many of the ingredients, resulting in products which do not look like whole foods in their natural state and do not contain the nutrients of the originals. The human body requires about forty different nutrients for health, healing, and growth. A diet of nutrient-poor processed foods may taste delicious and fill us up but will not provide the nutrients we need. The best way to satisfy the body’s nutritional needs is to eat nutrient-dense foods.

Food: A Better Source of Nutrients

It is better to get all your micronutrients from food than from supplements. Supplements contain only what is listed on the label, but foods contain macronutrients, multiple micronutrients, and other chemicals, like antioxidants, that benefit health. While supplements are a $20 billion industry in the United States and more than 50 percent of Americans use them daily, there is no consistent evidence that they are better than food in promoting health and preventing disease.

The USDA provides a FoodData Central search tool that will allow you to look up the nutrients present in different foods. It might surprise you to see the nutrients in your favorite foods. Find it here: USDA Food Data Central (https://fdc.nal.usda.gov/)

Guidelines for Healthy Choices

A healthful diet is rewarding, but economic, sociological, and cultural factors make it difficult. People have strong opinions and preferences about what they eat. The food industry has strong incentives to advertise their products and sell products that are profitable. To lead discussions among the public, the food industry, the government, and medical professionals, consistent guidelines are useful. A set of guidelines is developed by an independent, non-profit organization called the Food and Nutrition Board of the National Academies of Sciences, Engineering, and Medicine of the Institutes of Medicine (IOM) (https://www.nationalacademies.org/fnb/food-and-nutrition-board ).

The Board analyzes scientific data and provides recommendations about nutrition, food safety, and food policy. One important set of values, called the dietary reference intakes (DRIs), includes recommended amounts of nutrients that healthy people should eat daily. There are DRIs for recommended amounts of vitamins and minerals, for kcal ranges, and for macronutrient intakes for people of different ages and stages of life. The DRIs are used by:

• Individuals for their own information and choices
• Medical and nutrition professionals for advice and planning
• Food manufacturers for guidelines and labeling
• Government feeding programs (military, school, WIC, etc.). ^[1]

Daily Reference Intakes

DRIs include six reference values established by the IOM in the United States and used by the USDA to establish dietary guidelines. These values are:

• Recommended Dietary Allowances (RDA)
• Estimated Average Requirements (EAR)
• Adequate Intakes (AI)
• Tolerable Upper Intake Levels (UL)
• Acceptable Macronutrient Distribution Ranges (AMDR)
• Estimated Energy Requirement (EER).

The DRIs vary by age and sex and describe need of healthy individuals. DRIs are designed to be used as a guide for the majority of the healthy population, and as such, there will be some individuals for whom the DRIs will not apply. The DRIs are based on data gathered from healthy people in research studies.

Four of the DRIs are applicable to all types of nutrients and are frequently used to describe amounts of vitamins, minerals, fiber, and specific lipids. Two DRIs concern energy, and therefore they are only used in conversations about nutrients which provide energy in kcals (carbohydrates, lipids, and proteins).

The first four DRIs are:

• Estimated Average Requirement (EAR). This is the amount of a particular nutrient that meets the requirements of 50 percent of people in a target group (defined by sex, age, and life stage). It is based on data collected from healthy people. EAR values, by definition, do not fulfill the needs of half of the population, so they are not used for consumer advice. EAR values are the scientific foundation for RDAs, the next concept.
• Recommended Daily Allowances (RDA). Based statistically on the EAR, the RDA is the amount of a nutrient which meets the needs of the majority (97 to 98 percent) of the target healthy population. To determine a personal requirement for a nutrient, a blood test is necessary. However, using the RDA as a guideline is adequate for most people. RDAs are used in food and supplement labeling guidelines, so that consumers and manufacturers are speaking the same language.
• Adequate Intake (AI). AIs are created for nutrients when there is insufficient consistent scientific evidence to determine an EAR for a population. As with RDAs, AIs can be used as nutrient-intake goals for a given nutrient. For example, the DRI values for infants are AIs derived from nutrient values in human breast milk. For older babies and children, AI values are derived from human milk coupled with data on adults.
• Tolerable Upper Intake Levels (UL). Many nutrients can be harmful in high amounts. The UL was established to distinguish healthful and harmful nutrient intakes. Developed in part as a response to the growing usage of dietary supplements, ULs indicate the highest continuous intake of a nutrient that is considered safe. Taking in amounts above the UL is associated with health risks. Reaching the UL for a nutrient by eating food is unlikely. To reach vitamin C toxicity (2000 mg for an adult) by eating oranges, for example, would take 28 oranges, which would be a very unusual meal! The warning is usually important for supplements.

This graph illustrates the risks of nutrient inadequacy and nutrient excess from low intake of a nutrient to high intake. Starting on the left side of the graph, very low intake is associated with a high risk of nutrient deficiency. The point at which 50 percent of the population meets their nutrient need is the EAR, and the point at which 97 to 98 percent of the population meets their needs is the RDA. The UL is the highest level at which you can consume safely – nutrient intake increases beyond the UL, the risk of health problems resulting from that nutrient increases. This means that the majority of healthy individuals should consume an amount of a nutrient somewhere in between the RDA and the UL.

DRIs associated with energy are:

• Acceptable Macronutrient Distribution Range (AMDR). This defines the recommended percentage of kcals that come from each of the macronutrients – carbohydrates, fats, and protein. Staying within these ranges is recommended to provide adequate amounts of the various nutrients; these ranges are associated with a reduced risk of chronic disease. The ranges (Table 2.1) allows flexibility for preference and variation. The DRI committee recommends using the midpoint of the AMDRs as an approach to focus on moderation.^[2]

• Estimated Energy Requirement (EER). This is the recommended amount of energy, in kcals, that a person needs in a day. This varies based on several factors and will be discussed in depth in future chapters. A calculator is available here: DRI Calculator for Healthcare Professionals (https://www.nal.usda.gov/human-nutrition-and-food-safety/dri-calculator). Tables which include different ages and sexes are published in the Dietary Guidelines for Americans 2020-2025, pages 139-141.

You can use the DRIs to help assess and plan your diet. The values are meant to plan average intake over time; that is, you don’t need to meet these recommendations every single day—meeting them on average over several days is sufficient.

Lifestyles and Nutrition

Health is affected by genetics, the environment, life cycle, and lifestyle as well as nutrition. Dietary habits include what a person eats, how much a person eats during a meal, how frequently meals are consumed, and how often a person eats out. Other aspects of lifestyle include physical activity level, recreational drug use, and sleeping patterns, all of which play a role in health and impact nutrition. Following a healthy lifestyle improves your overall health.

Physical Activity

In 2018, the Health and Human Services (HHS) updated the Physical Activity Guidelines for Americans ^[3] asserting that “Being physically active is one of the most important steps that Americans of all ages can take to improve their health.” The guidelines recommend exercise programs for different life. Increased physical activity decreases the risk of early death, heart disease, stroke, type 2 diabetes, high blood pressure, and certain cancers; prevents weight gain and falls; and improves cognitive function in the elderly. The Physical Activity Guidelines recommend combinations of moderate aerobic activity and muscle and bone strengthening exercises. Ideally physical activity should be spread over at least three days of the week. A guide for appropriate intensity during exercise is that one should be able to “talk, but not sing”.^[3] High intensity aerobic exercise interferes with speaking more than a few words at a time. Sedentary individuals should start exercise programs slowly to minimize damage to the skeletomuscular system.

The “Move Your Way” campaign made specific recommendations for adults’ physical activity, as seen in Figure 2.2. Adults are recommended to perform moderate-intensity heart rate-raising aerobic activity for at least 150 minutes per week (or at least 75 minutes per week of vigorous aerobic activity like running) and to perform muscle-strengthening activity at least 2 days per week. But for those who such activity is not possible, doing even 5 minutes of physical activity is beneficial.

Recreational Drug Use

Recreational drug use, including tobacco, electronic smoking devices, and alcohol consumption along with narcotic and other illegal drug use, has a large impact on health. Smoking cigarettes can cause lung cancer, eleven other types of cancer, heart disease, and several other disorders or diseases that markedly decrease quality of life and increase mortality. In the United States, smoking causes more than 480,000 deaths every year^[4].

Also, according to the Centers for Disease Control and Prevention (CDC), excessive alcohol intake causes an estimated 178,000 deaths per year.^[5] Staying away from excessive alcohol intake lowers blood pressure, the risk from injury, heart disease, stroke, liver problems, and some types of cancer. While excessive alcohol consumption can be linked to poor health, consuming alcohol in moderation has been found to reduce the risk for heart disease and Type 2 diabetes in some people. The CDC defines drinking in moderation as no more than one drink a day for women and two drinks a day for men.^[6]

Illicit and prescription drug abuse are associated with decreased health and is a prominent problem in the United States. The health effects of drug abuse can be far-reaching, including the increased risk of stroke, heart disease, cancer, lung disease, and liver disease.^[7]

Recreational drug use can increase the need for some nutrients. For example, exposure to cigarette smoke depletes the body’s vitamin C, and therefore, the recommended intake of vitamin C is higher for smokers ^[2]. Alcohol also has a negative impact on nutrient levels in the body, for several different reasons. Alcohol abuse can lead to malnutrition.^[8].

Sleeping Patterns

Diet has a strong effect on both the quality of sleep and the amount of sleep^[9]. Inadequate sleep affects health by increasing short-term fatigue and lack of focus; it is also associated with increased caloric intake and irregular eating patterns. Sleep disturbances affect levels of hormones associated with appetite regulation and metabolism. Poor sleep and weight gain show a strong relationship^[9], implicating healthy sleep patterns as an important corollary to a healthy diet.

Food and Culture

Many cultural factors influence food decisions. Shared food traditions are associated with a sense of belonging in a community and can reinforce family, cultural, religious and national identity. Special foods for different occasions are found in all cultures.

Typically, eating kosher food means a person is Jewish; eating fish on Fridays during Lent means a person is Catholic; fasting during the ninth month of the Islamic calendar means a person is Muslim. On New Year’s Day, Japanese take part in an annual tradition of Mochitsuki also known as Mochi pounding in hopes of gaining good fortune over the coming year. Several hundred miles away in Hawai‘i, people eat poi made from pounded taro root with great significance in the Hawaiian culture. National food traditions are carried to other countries when people immigrate.

Factors that Drive Food Choices

Along with these influences, a number of other factors affect the dietary choices individuals make, including:

• Taste, texture, and appearance. Individuals have preferences which influence their food choices. However, creative cooks can adapt healthy foods to meet most people’s taste. Adventurous diners often find new foods to like when they take chances!
• Economics. Access to fresh fruits and vegetables may be scant, particularly for those who live in economically disadvantaged or remote areas, where cheaper food options are limited to convenience stores and fast food.
• Early food experiences. People who were not exposed to different foods as children, or who were forced to swallow every last bite of overcooked vegetables, may make limited food choices as adults.
• Habits. It’s common to establish eating routines, which can work both for and against optimal health. Habitually grabbing a fast food sandwich for breakfast can seem convenient, but might not offer substantial nutrition. Yet getting in the habit of drinking an ample amount of water each day can yield multiple benefits.
• Culture. The culture in which one grows up affects how one sees food in daily life and on special occasions.
• Geography. Where a person lives influences food choices. For instance, people who live in Midwestern US states have less access to seafood than those living along the coasts.
• Advertising. The media greatly influences food choice by persuading consumers to eat certain foods.
• Social factors. Any school lunchroom observer can testify to the impact of peer pressure on eating habits, and this influence lasts through adulthood. People make food choices based on how they see others and want others to see them. For example, individuals who are surrounded by others who consume fast food are more likely to do the same.
• Emotions. There is a wide range in how emotional issues affect eating habits. When faced with a great deal of stress, some people tend to overeat, while others find it hard to eat at all.
• Green food/Sustainability choices. Based on a growing understanding of diet as a public and personal issue, more and more people are starting to make food choices based on their environmental impact. Realizing that their food choices help shape the world, many individuals are opting for a vegetarian diet, or, if they do eat animal products, striving to find the most “cruelty-free” options possible. Purchasing local and organic food products and items grown through sustainable products also helps shrink the size of one’s dietary footprint.

People choose a vegetarian diet for various reasons, including religious doctrines, health concerns, ecological and animal welfare concerns, or simply because they dislike the taste of meat. There are different types of vegetarians, but a common theme is that vegetarians do not eat meat. Four common forms of vegetarianism are:

• Lacto-ovo vegetarian. This is the most common form. This type of vegetarian diet includes the animal foods eggs and dairy products.
• Lacto-vegetarian. This type of vegetarian diet includes dairy products but not eggs.
• Ovo-vegetarian. This type of vegetarian diet includes eggs but not dairy products.
• Vegan. This type of vegetarian diet does not include dairy, eggs, or any type of animal product or animal by-product.

Achieving a Healthy Diet

Five important characteristics of a healthful diet are:

• Adequacy. It must include sufficient energy (kcals) and nutrients, including fiber, healthy fats, and water.
• Nutrient balance. It must include appropriate amounts of all nutrients.
• Energy balance. Caloric intake should match energy expenditure.
• Moderation. Moderation means eating enough and avoiding overeating.
• Variety. Consuming different foods gives the best chance of obtaining enough of each of the 40 nutrients required by humans and avoiding excess exposure to contaminants present in one type of food (such as a spray on a particular fruit, or mercury in seafood).

Themes of the 2025-2030 Dietary Guidelines

The 2025-2030 edition of the USDA Dietary Guidelines for Americans in some ways represent a significant departure from previous editions. As an obvious example, this newest edition is 10 pages long^[10], compared to the 2020-2025 edition’s 164 pages^[11]. In another example of change, the new Guidelines emphasize full-fat dairy and red meat, in contradiction to previous Guidelines and their supporting scientific reports. Other parts of the Guidelines did not change much in the new edition. For example, specific recommendations for water, saturated fat, and sodium remain unchanged.

The markedly short new Guidelines came with supporting documents that replace some of the information and context lost in those 150ish pages, though this results in some uncertainties or even possible contradictions between the various documents. The expression of vegetable and fruit recommendations changed in the new Guidelines compared to the previous edition, but it requires consulting a supplementary Daily Servings By Calorie Level document to determine that the recommended amounts are not actually different than previously.^[12]

The previous recommendation of saturated fats accounting for no more than 10% of daily kilocalories remains in the new Guidelines, but seems to be in disagreement with the emphasis on full-fat dairy and red meat in part to “prioritize protein foods.” Red meat and full-fat dairy are also relatively high in saturated fat–an apparent contradiction with the recommendation to limit saturated fat intake. Research indicates that replacing saturated fat with unsaturated fat reduces risk of cardiovascular disease; while research on the health effects of saturated fat continues, the American Heart Association maintains its strong recommendations to limit saturated fats and to choose unsaturated fats instead.^[13]

There is also vagueness in the 2025-2030 Guidelines. Limiting consumption of alcohol is recommended, but without a specific number of standard drinks as was previously the case.

The new Guidelines increase American’s recommended protein intake to 1.2-1.6 grams of protein per kilogram of body weight, notably higher than the unchanged Recommended Dietary Allowance (RDA) of 0.8 g/kg. However, a systematic review of studies rated as having low to moderate risk of bias commissioned by the Joint Canada-United States Dietary Reference Intakes (DRIs) Working Group did not find sufficient evidence to change protein recommendations.^[14] Concerns around the Guidelines’ approach protein and saturated fat has led some experts to highlight financial ties of several 2025-2030 Guidelines authors to beef, dairy, and other food industry groups.^[15]

It should be noted that some new emphases in the new Guidelines did receive a warm reception among nutrition experts. The strong recommendations to limit added sugars and highly processed foods have been viewed as improvements, for example.^[16]

The 2025-2030 Guidelines make the following general recommendations:

• Eat the right amount for you: depends on age, sex, height, weight, physical activity
• Prioritize protein foods at every meal: eat high-quality, nutrient-dense protein foods
• Consume dairy: stick to sources with no added sugars
• Eat vegetables and fruits throughout the day: consume a variety of colorful, nutrient dense vegetables and fruits
• Incorporate healthy fats
• Focus on whole grains: favor fiber-rich whole grains over processed sources
• Limit highly processed foods, added sugars, and refined carbohydrates: choose nutrient-dense foods and home-prepared meals instead.

Key Guidelines recommendations of public health concern in the United States include advice to

• Consume less than 10 percent of kcals per day from saturated fats,
• Consume less than 2,300 mg per day of sodium,
• Limit added sugars to no more than 10 g at any meal and avoid entirely when possible,
• Limit alcohol consumption (though with no specific maximum number of drinks).

References

1. Office of Dietary Supplements, National Institute of Health. Nutrient Recommendations: Dietary Reference Intakes (DRI). https://ods.od.nih.gov/HealthInformation/nutrientrecommendations.aspx. Accessed Aug 14 2024.
2. National Institutes of Health. Vitamin C: Fact Sheet for Health Professionals. https://ods.od.nih.gov/factsheets/VitaminC-HealthProfessional/. Updated February 27, 2020. Accessed December 30, 2020.
3. U.S. Department of Health and Human Services. (2018) Physical Activity Guidelines for Americans 2^nd edition. Washington, DC: U.S. Department of Health and Human Services. https://health.gov/sites/default/files/2019-09/Physical_Activity_Guidelines_2nd_edition.pdf Accessed Aug 14 2024.
4. Centers for Disease Control and Prevention. “Cigarette Smoking. https://www.cdc.gov/tobacco/about/index.html Updated September 17, 2024. Accessed March 2, 2026.
5. Centers for Disease Control and Prevention. “Facts About U.S. Deaths from Excessive Alcohol Use.” https://www.cdc.gov/alcohol/facts-stats/index.html. Updated July 3, 2024. Accessed March 2, 2026.
6. Centers for Disease Control and Prevention. “About Moderate Alcohol Use.” https://www.cdc.gov/alcohol/about-alcohol-use/moderate-alcohol-use.html Updated January 14, 2025.  Accessed May 10, 2026.
7. National Institute on Drug Abuse. Health Consequences of Drug Misuse. https://web.archive.org/web/20210123030457/https://www.drugabuse.gov/drug-topics/health-consequences-drug-misuse/introduction Archived from original: https://www.drugabuse.gov/related-topics/health-consequences-drug-misuse. Updated June, 2020. Accessed August 14, 2024.
8. National Institute on Alcohol Abuse and Alcoholism. Alcohol Alert. https://web.archive.org/web/20200602111352/https://pubs.niaaa.nih.gov/publications/aa22.htm Archived from original: https://pubs.niaaa.nih.gov/publications/aa22.htm Updated October, 2000. Accessed August 14, 2024.
9. Frank S, Gonzalez K, Lee-Ang L, Young MC, Tamez M and Mattei J (2017) Diet and Sleep Physiology: Public Health and Clinical Implications. Front. Neurol. 8:393. doi: 10.3389/fneur.2017.00393
10. United States Department of Agriculture. Dietary Guidelines for Americans, 2025-2030. https://realfood.gov/
11. United States Department of Agriculture. Dietary Guidelines for Americans, 2020-2025. https://www.dietaryguidelines.gov/about-dietary-guidelines/previous-editions/2020-dietary-guidelines
12. United States Department of Agriculture. Daily Servings by Calorie Level, 2025-2030. https://realfood.gov/
13. Lichtenstein AH, et al. 2026 Dietary Guidance to Improve Cardiovascular Health: A Scientific Statement From the American Heart Association. Circulation. 2026; 153(18): e1285-e1295. https://doi.org/10.1161/CIR.0000000000001435
14. Burstad et al. Evaluation of dietary protein and amino acid requirements: a systematic review. The American Journal of Clinical Nutrition. 2025; 122(1): 285-305. https://doi.org/10.1016/j.ajcnut.2025.04.017
15. Physicians Committee for Responsible Medicine. “New Dietary Guidelines Were Written by Authors With Strong Ties to the Food Industry, Doctors Report.” https://www.pcrm.org/news/news-releases/new-dietary-guidelines-were-written-authors-strong-ties-food-industry-doctors Published January 7, 2026. Accessed May 10, 2026.
16. Nestle M. “The MAHA 2025-2030 Dietary Guidelines have arrived: Cheerful, Muddled, Contradictory, Ideological, Retro.” Food Politics (blog). https://www.foodpolitics.com/2026/01/the-maha-2025-2030-dietary-guidelines-have-arrived-cheerful-muddled-contradictory-ideological-retro/ Published January 8, 2026. Accessed May 10, 2026.

Attributions

Adapted by Pattie S. Green, Ph.D. and Jonathan Pottle, Ph.D., Tacoma Community College  from Human Nutrition by University of Hawai‘i at Mānoa Food Science and Human Nutrition Program which is licensed under a Creative Commons Attribution 4.0 International License:. Specifically, the following sections were adapted here:

• Chapter 12 Nutrition Applications Introduction
• Understanding Daily Reference Intakes
• Lifestyles and Nutrition
• Understanding the Bigger Picture of Dietary Guidelines