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9.2: Planning a Diet

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  • The definition of diet is anything that is consumed by a particular person or people on a regular basis. That means if someone routinely drinks coffee in the morning, that is part of his/her diet. If a person consistently eats a Big Mac from McDonald’s, that is part of his/her diet. However, it is clear that food choices influence short-term and long-term health. That is why it is so important to make wise choices in what one eats on a regular basis. If a person chooses to have a diet high in calories without balancing energy use, that person can expect to put on unhealthy weight. A diet that is high in fiber, with the appropriate amount of calories and proper amounts of the macronutrients, will contribute to a healthy body.

    When people discuss “going on a diet,” they are actually talking about changing their existing dietary habits in order to change their body shape. All people are “on a diet” because everyone eats! Many times, the term diet is thought of as a method to lose weight or to change body shape. However, it is important to focus on the nutritional concepts listed below, so long-term health can be achieved.

    Decisions about nutrition can be difficult. Knowing and using scientific research can lead to better health. Over time public health organizations have developed tools based on nutritional science to help people design healthy diets. These tools should be used as guidelines for each individual with the awareness that everyone is different and therefore has different needs. Everyone, regardless of age, size, shape, physique, can benefit from learning and utilizing the following tools:

    Acceptable Macronutrient Distribution Range (AMDR)

    The AMDR describes the proportions of daily caloric intake that should be carbohydrates, lipids, and proteins. Basically the AMDR provides guidelines on how many macronutrient calories one should consume a day.

    According to the AMDR, the range of caloric intake in a daily diet should be:

    • Carbohydrates: 45-65%
    • Lipids: 20-35%
    • Proteins: 10-35%

    Dietary Reference Intakes (DRI)

    The DRI’s are reference values of nutrient intake that help with nutrition planning and assessment of healthy individuals. There are four measures that together comprise the DRI:

    • Recommended Dietary Allowance (RDA): the average daily dietary intake level that is sufficient to meet the nutrient requirement of nearly all (about 97%) healthy individuals in a group. This is the basic quantity of a nutrient recommended.
    • Adequate Intake (AI): a value based on observed or experimentally determined approximations of nutrient intake by a group (or groups) of healthy people—used when an RDA cannot be determined. This is the minimum amount of a nutrient needed for maintaining health.
    • Tolerable Upper Intake Level (UL): the highest level of daily nutrient intake that is likely to pose no risk of adverse health effects to almost all individuals in the general population. As intake increases above the UL, the risk of adverse effects increases. This is the maximum that would be consumed prior to developing negative effects of eating too much. This is not a level that is met, but rather one that is avoided to prevent a decrease in health.
    • Estimated Average Requirement (EAR): a nutrient intake value that is estimated to meet the requirement of half the healthy individuals in a group. These nutrient values should be used as goals for dietary intake for health.

    4 Key Concepts for Personalizing a Healthy Diet

    Personalizing meal plans can be extremely beneficial psychologically as well as physically. Knowing that one is eating healthy reduces some of the subconscious doubts about doing what needs to be done to be well. However, as with every healthy practice, there can be pitfalls. To help avoid these, there are 4 approaches that can be taken:

    1. Assessing and changing your diet
    2. Staying committed to a healthy diet
    3. Try additions and substitutions to bring your current diet closer to your goals
    4. Plan ahead for challenging situations

    Planning Healthy Meals

    Individual requirements for nutrients vary considerably depending on factors such as age and gender. Other relevant factors are size, metabolic rate, and occupation. A farmer would have a different dietary need than someone in a sedentary occupation. The body also has stores of certain nutrients (fat-soluble vitamins, for example) so that variations in daily intake of such nutrients can be accommodated. Thus it could be misleading to recommend a particular daily intake level.

    When considering dietary needs, various techniques have been established by health officials to assist people in choosing foods and food amounts wisely. Choose My Plate is a graphic representation of what a healthy plate of food might look like. Other tools, such as meal planning guides have also been established.

    Nutrition Labels

    Perhaps one of the most effective tools provided to consumers is the nutrition label that is by law on all food packaging. This information can be useful for evaluating the nutrient content of food and planning healthy meals.

    Understanding Food Labels

    In the United States, the Food and Drug Administration (FDA) requires packaged foods to have a label that helps consumers make educated decisions about the foods they purchase. The label provides caloric, macronutrient, and some micronutrient content of the food. Labels also indicate ingredients and manufacturer information.

    Understanding the information on food labels can lead to healthy choices about food. This page will outline how to interpret food labels.

    FYI: Food labels do not provide all nutritional information; they just include the basics to help consumers make healthy food decisions.

    Information On Food Labels

    • Name of product: Sometimes the name of the product includes important information. For example some brands are vegetarian, kosher, gluten-free, etc. It is also important to compare/contrast ingredients in generic and brand name foods
    • Serving Size: It’s important to pay attention to how many servings a package contains. Many packages contain multiple servings.

    Figure \(\PageIndex{1}\). Using your hand to determine serving size

    • Calories: Pay attention to whether the caloric content of the food is per serving or per package. Also, some food labels indicate calories before or after preparation.
    • Fats: The food label includes all fats. Note that the label indicates different types of fats. A later chapter will address different fats and how they are important in human nutrition.
    • Cholesterol: Dietary cholesterol is a major factor in cardiovascular health. Limiting the intake of cholesterol can prevent heart disease.
    • Sodium: Another major factor in promoting good health is limiting the amount of sodium intake.
    • Carbohydrates: The food label includes simple and complex carbohydrates. Note that the label indicates different types of carbohydrates; a later chapter will address these and how they are important in human nutrition.
    • Proteins: Protein intake needs to be carefully monitored because over or under consumption of protein can cause severe issues.
    • Vitamins and Minerals: There are four vitamins and minerals (Vitamin D, Calcium, Iron, and Potassium) that are required on food labels; however, the label might include more than these four.
    • Ingredients: The ingredients are listed in order of their content per volume. If sugar is listed as the first ingredient, there is more sugar in the food than any other ingredient. The last ingredient has the least amount in the food.
    • Name of manufacturer: In addition to the Nutrition Facts, the food label includes the name and contact information for the manufacturer as required by law.
    • Allergens: Food manufacturers are required to draw specific attention to common allergens such as nuts, milk products, soy, etc. There is no specific location for allergen information, but it should be someplace on the packaging.

    Figure \(\PageIndex{2}\). Nutrition Facts

    To learn additional details about all of the information contained within the Nutrition Facts panel, see the following website:

    Finding Quality Nutrition Research

    “New study shows that margarine contributes to arterial plaque.” “Asian study reveals that two cups of coffee per day can have detrimental effects on the nervous system.” How do you react when you read news of this nature? Do you boycott margarine and coffee? When reading nutrition-related claims, articles, websites, or advertisements always remember that one study does not substantiate a fact. One study neither proves nor disproves anything. Readers who may be looking for complex answers to nutritional dilemmas can quickly misconstrue such statements and be led down a path of misinformation. Listed below are ways that you can develop discerning eyes when reading nutritional news.

    • The scientific study under discussion should be published in a peer-reviewed journal, such as the Journal of the International Society of Sports Nutrition. Question studies that come from less trustworthy sources (such as non peer-reviewed journals or websites) or that are not published.
    • The report should disclose the methods used by the researcher(s). Did the study last for three or thirty weeks? Were there ten or one hundred participants? What did the participants actually do? Did the researcher(s) observe the results themselves or did they rely on self -reports from program participants?
    • Who were the subjects of this study? Humans or animals? If human, are any traits/characteristics noted? You may realize you have more in common with certain program participants and can use that as a basis to gauge if the study applies to you.
    • Credible reports often disseminate new findings in the context of previous research. A single study on its own gives you very limited information, but if a body of literature supports a finding, it gives you more confidence in it.
    • Peer-reviewed articles deliver a broad perspective and are inclusive of findings of many studies on the exact same subject.
    • When reading such news, ask yourself, “Is this making sense?” Even if coffee does adversely affect the nervous system, do you drink enough of it to see any negative effects? Remember, if a headline professes a new remedy for a nutrition-related topic, it may well be a research-supported piece of news, but more often than not it is a sensational story designed to catch the attention of an unsuspecting consumer. Track down the original journal article to see if it really supports the conclusions being drawn in the news report.

    When reading information on websites, remember the following criteria for discerning if the site is valid:

    • Who sponsors the website?
    • Are names and credentials disclosed?
    • Is an editorial board identified?
    • Does the site contain links to other credible informational websites? Even better, does it reference peer-reviewed journal articles? If so, do those journal articles actually back up the claims being made on the website?
    • How often is the website updated?
    • Are you being sold something at this website?
    • Does the website charge a fee?

    Trustworthy Sources

    Now let’s consider some reputable organizations and websites from which you can obtain valid nutrition information.

    Organizations Active in Nutrition Policy and Research

    1. US Department of Agriculture Food and Nutrition Information Center. The USDA site has more than twenty-five hundred links to dietary, nutrition, diet and disease, weight and obesity, food-safety and food-labeling, packaging, dietary supplement and consumer questions sites. Using this interactive site, you can find tips and resources on how to eat a healthy diet, my Foodapedia, and a food planner, among other sections.
    2. The Academy of Nutrition and Dietetics (AND). The AND promotes scientific evidenced-based, research-supported food and nutrition related information on its website, It is focused on informing the public about recent scientific discoveries and studies, weightloss concerns, food safety topics, nutrition issues, and disease prevention.
    3. Department of Health and Human Services. The HHS website,, provides credible information about healthful lifestyles and the latest in health news. A variety of online tools are available to assist with food-planning, weight maintenance, physical activity, and dietary goals. You can also find healthful tips for all age groups, tips for preventing disease, and on daily health issues in general.
    4. Centers for Disease Control and Prevention. The Centers for Disease Control and Prevention ( distributes an online newsletter called CDC Vital Signs. This newsletter is a valid and credible source for up-to-date public health information and data regarding food, nutrition, cholesterol, high blood pressure, obesity, teenage drinking, and tobacco usage.
    5. Dietitians of Canada. Dietitians of Canada,, is the national professional association for dietitians. It provides trusted nutrition information to Canadians and health professionals.

    Genetically Modified Foods

    Genetically modified foods (also known as GM or GMO foods), are plants or animals that have undergone some form of genetic engineering. In the United States, much of the soybean, corn, and canola crop is genetically modified. The process involves the alteration of an organism’s DNA, which allows farmers to cultivate plants with desirable characteristics.

    For example, scientists could extract a gene that produces a chemical with antifreeze properties from a fish that lives in an arctic region (such as a flounder). They could then splice that gene into a completely different species, such as a tomato, to make it resistant to frost, which would enable farms to grow that crop year-round.

    Certain modifications can be beneficial in resisting pests or pesticides, improving the ripening process, increasing the nutritional content of food, or providing resistance to common viruses. Although genetic engineering has improved productivity for farmers, it has also stirred up debate about consumer safety and environmental protection. Possible side effects related to the consumption of GM foods include an increase in allergenicity, or tendencies to provoke allergic reactions. There is also some concern related to the possible transfer of the genes used to create genetically engineered foods from plants to people. This could influence human health if antibiotic-resistant genes are transferred to the consumer. Therefore, the World Health Organization (WHO) and other groups have encouraged the use of genetic engineering without antibiotic-resistance genes. Genetically modified plants may adversely affect the environment as well and could lead to the contamination of non-genetically engineered organisms.

    Genetically modified foods fall under the purview of the EPA, the USDA, and the FDA. Each agency has different responsibilities and concerns in the regulation of GM crops. The EPA ensures that pesticides used for GM plants are safe for the environment. The USDA makes sure genetically engineered seeds are safe for cultivation prior to planting. The FDA determines if foods made from GM plants are safe to eat. Although these agencies act independently, they work closely together and many products are reviewed by all three.

    Organic food products

    Organically produced foods have been cultivated or raised without synthetic pesticides, antibiotics, or genetic engineering. Certified organic foods can be identified by the USDA’s stamp and is usually more expensive than conventionally produced foods. There have been a lot of questions about the nutritional superiority of organic foods over those traditionally produced. These questions do not have simple answers. Most studies differ substantially in their methodology and involve many different aspects of the food being studied. The USDA makes no claims that organic food is safer or more nutritious than conventionally produced food, and indeed many organic foods - e.g., milk, butter, ice cream, meat - are likely to match their conventional counterparts for fat and calories.

    There are, however, specific health reasons that motivate shoppers to buy natural or organic, foods. For instance, people with food allergies, chemical allergies or intolerance to preservatives can substitute organic foods, personal care products and clothing. To reduce fat and cholesterol in their diets, consumers can replace meat with products made from organic soy, wheat or vegetables.

    Some organic foods also have significantly higher levels of cancer- fighting antioxidants, according to a study of corn, strawberries and marionberries, which was published in Feb.26, 2003, in the Journal of Agriculture and Food Chemistry, a peer-reviewed publication of the American Chemical Society ("Bitter or Harsh Phenalics Guard the Plant Against These Pests").

    Some officials say, however, that organic foods may at times 'be less safe than conventional foods. In October 2002, USDA's undersecretary for food safety warned that organic foods' lack of preservatives makes them vulnerable to bacteria and parasites. The following month., the Institute of Food Technologies issued a release stating that organics "have the potential for greater pathogen contamination." Also in 2002, records from the U.S. Food and Drug Administration and Health Canada revealed that organic and all-natural products are eight times more likely to be recalled for safety problems, including bacterial contamination. Organic products are as safe as conventional ones, according to the ` Organic Trade Association. "Certified organic growers follow strict guidelines for safe and hygienic food production. As with all food producers, they must comply with local, state and federal health standards.

    Dietary Food Trends

    Hundreds of years ago, when food was less accessible and daily life required much more physical activity, people worried less about obesity and more about simply getting enough to eat. In today’s industrialized nations, conveniences have solved some problems and introduced new ones, including the hand-in-hand obesity and diabetes epidemics. Fad diets gained popularity as more North Americans struggled with excess pounds. However, new evidence-based approaches that emphasize more holistic measures are on the rise. These new dietary trends encourage those seeking to lose weight to eat healthy, whole foods first, while adopting a more active lifestyle. These sound practices put dietary choices in the context of wellness and a healthier approach to life.

    Functional Foods

    Many people seek out foods that provide the greatest health benefits. This trend is giving rise to the idea of functional foods, which not only help meet basic nutritional needs but also are reported to fight illness and aging. According to the Academy of Nutrition and Dietetics (AND), formerly known as the The Academy of Nutrition and Dietetics, functional foods may reduce the risk of disease or promote optimal health. The AND recognizes four types of functional foods. They are: conventional foods, modified foods, medical foods, and special dietary use foods.

    The first group, conventional foods, represents the simplest form of functional foods. They are whole foods that have not been modified. Examples include whole fruits and vegetables (which are abundant in phytochemicals and antioxidants), yogurt and kefir (which contain natural probiotic bacteria that can help maintain digestive system health), and dark chocolate (which contains antioxidants).

    • Modified foods have been fortified, enriched, or enhanced with additional nutrients or bioactive compounds. Foods are modified using biotechnology to improve their nutritional value and health attributes. Examples of modified foods include calcium-fortified orange juice, breads enriched with B vitamins, iodized salt, cereals fortified with vitamins and minerals, margarine enhanced with plant sterols, and energy drinks that have been enriched with herbs (ginseng or guarana) or amino acids (taurine). It is important to consider that the health claims of some modified foods may be debatable, or entirely fraudulent. Check with a health professional regarding the effects of modified foods on your health.
    • Medical foods are designed for enteric administration under the guidance of a medical professional. (During enteric administration, food is treated so that it goes through the stomach undigested. Instead, the food is broken down in the intestines only.) Medical foods are created to meet very specific nutritional requirements. Examples of medical foods include liquid formulas for people with kidney disease, liver disease, diabetes, or other health issues. Medical food is also given to comatose patients through a gastronomy tube because they cannot eat by mouth.
    • Special dietary use foods do not have to be administered under a doctor’s care and can be found in a variety of stores. Similar to medical foods, they address special dietary needs and meet the nutritional requirements of certain health conditions. For example, a bottled oral supplement administered under medical supervision is a medical food, but it becomes a special dietary use food when it is sold to retail customers. Examples of special dietary use foods include gluten-free foods, lactose-free dairy products, and formulas and shakes that promote weight loss.