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Dietary assessment in adults

Dietary assessment in adults
Author:
Barbara Olendzki, RD, MPH, LDN
Section Editor:
David Seres, MD
Deputy Editor:
Jane Givens, MD, MSCE
Literature review current through: Dec 2022. | This topic last updated: Oct 08, 2021.

INTRODUCTION — The goal of dietary assessment is to identify appropriate and actionable areas of change in the patient's diet and lifestyle and to improve patient health and wellbeing.

Patients with complex dietary concerns should receive a comprehensive assessment by a dietitian. A complete assessment will examine multiple components, including the physical ability to chew and swallow food; evaluation for food intolerances; ability to digest and absorb foods; evaluation of possible eating disorders and appetite fluctuations; unintentional weight loss or gain; taste changes; and the skills and ability to comply with dietary lifestyle changes (shopping, cooking, and understanding of the dietary plan).

Patients can and should be adequately assessed and triaged in primary care settings, which can be expected to take 5 to 15 minutes. They may then be referred appropriately if their needs are more complex. This topic will discuss methods for assessing a patient's diet and related behaviors in the primary care setting.

Specific dietary and nutritional counseling recommendations will depend on the patient's comorbidities and are discussed in the appropriate topics. As examples:

Type 2 diabetes mellitus (see "Nutritional considerations in type 2 diabetes mellitus")

Obesity (see "Obesity in adults: Dietary therapy")

Inflammatory bowel disease (see "Nutrition and dietary management for adults with inflammatory bowel disease")

Cardiovascular disease (see "Prevention of cardiovascular disease events in those with established disease (secondary prevention) or at very high risk", section on 'Diet')

Gastroesophageal reflux disease (see "Medical management of gastroesophageal reflux disease in adults", section on 'Lifestyle and dietary modification')

DIETARY ASSESSMENT — The purpose of the dietary assessment is to obtain relevant information from the current diet to identify dietary components that may raise or lower health risks. This assessment determines which dietary and lifestyle changes might be appropriate, and which existing beneficial dietary habits should be encouraged.

Assessment options — Depending on the time available, dietary habits can be assessed quickly with a few questions, or more formally with a 24-hour dietary recall (form 1), food diary, or food frequency questionnaire (table 1). Various online tracking applications and tools are available to facilitate these assessments. (See 'Assessment tools' below.)

Quick approach — Simply asking patients, "What can you do to improve your diet?" can reduce time spent in assessment by highlighting areas the patient may be willing to consider changing while also demonstrating their level of insight. Patients often can inform the clinician of the areas of weakness in their diet and which behaviors contribute to body weight or other adverse health risks (such as elevated blood sugars).

Patients are often aware of their overeating and excessive portion sizes. It may not be necessary to have them track calories, but decreasing portions with smaller plates and bowls and avoiding second helpings could be helpful.

It is important to identify strengths in the diet (fruit, vegetables, whole grains, and other healthy options) to build upon positive dietary foundations. The clinician may then follow up in subsequent visits to assess patient changes, which is important for patient motivation and accountability.

Simple advice can improve a patient's diet. A recommendation of increasing fiber or lowering saturated fat, by providing specific food examples, can also have a beneficial impact on other areas of the diet [1,2]. Patients who consume sweetened beverages (eg, soda, sugary waters, juice, sweetened iced tea, coffee, and sports drinks) can improve their diets by decreasing consumption of these beverages and any added sugars [3,4]. Also, intake of trans-fatty acids often comes from packaged and processed foods with hydrogenated or partially hydrogenated oils (eg, dry mixes, creamers, frozen or boxed foods, and baked goods such as cakes, cookies, crackers, pies and breads) [5]. Eliminating consumption of these products can add up to large changes over time [6]. (See "Dietary fat" and "Healthy diet in adults", section on 'Added sugars and sugar-sweetened beverages'.)

24-hour dietary recall — A dietary assessment tool commonly used is the 24-hour dietary recall [7]. The goal of the 24-hour dietary recall is to identify the day-to-day pattern of eating with a minimum of reporting bias [8,9]. Most people have little variability in their dietary patterns and are remarkably consistent with caloric intake and food choices. The clinician will ask what the patient consumed in the last 24 hours, including beverages, and, if time permits, may also ask about the portion sizes of the foods. To save time, the clinician may focus on the evening meal and snacks consumed before bedtime. This is often the area of concern and changes from this alone can make a beneficial difference. (See 'Estimating portion sizes' below.)

The methodology of the 24-hour dietary recall is to query the previous day's intake, separating meal occurrences: "What is the first thing you had to eat or drink yesterday?"; "Did you have anything else at the time?"; "What was the next thing you had to eat or drink?" Continue asking questions with a timeframe, including snacks before bedtime and any night eating. Ask the time the patient went to bed, so as to calculate when they ate their last meal (helpful when assessing gastroesophageal reflux disease [GERD], irritable bowel syndrome [IBS], etc). Ask about where foods are eaten (eg, home, work, restaurants). This exercise can also elicit behaviors and lifestyle factors that underlie dietary choices. (See 'Behavioral assessment' below.)

Remember that patients frequently fail to report beverage and alcohol consumption and most patients will require regular prompting such as, "What did you have to drink with that?" Patients should also be asked about frequency and quantity of alcohol consumption.

Ask about combined foods, such as cream in coffee and butter on bread. As in other settings, we avoid leading questions. For example, ask if the patient had anything on or with the bread, rather than if he had butter on the bread.

Food diary — Another option for dietary assessment is to ask the patient to bring in a three- or four-day food diary that contains a complete record of foods and beverages consumed over those days. This transfers much of the time burden from the clinician to the patient [10]. Then, highlight foods that need to be changed in addition to any beneficial choices that should be continued.

The diary itself can be an excellent tool to help patients increase awareness of their eating habits and to encourage compliance with recommended dietary changes [11]. Patients may alter what they consume and increase their awareness of intake because they are asked to write it down.

Additional questions may be needed to clarify the patient's diet around areas of concern (ie, sodium, carbohydrate, fiber). A food frequency questionnaire is useful in this setting.

Food frequency questionnaire — An abbreviated assessment may be performed by obtaining only the frequency of typical foods that are consumed in the diet (table 1) [12]. This is especially useful in identifying healthy foods which can be grouped but is not as useful in identifying unhealthy and processed foods which are ubiquitous in every food category. The food frequency questionnaire will cover typical intake over a period of time (usually a week or a month).

Focus on one or more key areas that are correlated with your patient's health concerns. Ask how often the patient consumes the food and then probe for greater detail. For example, if the patient has a high low-density lipoprotein (LDL) cholesterol level, you may want to explore sources of saturated fat and hydrogenated fats (trans-fats), such as meats, cheese, processed foods, snacks, and dairy products. For this same patient, it may also be appropriate to identify sources of soluble fiber which may be missing from the patient's diet (oats, barley, legumes, nuts, seeds, fruit, and vegetables) [6]. (See "Lipid management with diet or dietary supplements", section on 'Our approach'.)

Many patients are overfed in calories but lacking in healthy foods. What is missing in the diet is equally important to what may be in excess. Food frequency assessments can reveal that a patient is not eating a variety of fruit, vegetables, whole grains, nuts, seeds, legumes, and fish. (See "Healthy diet in adults".)

Estimating portion sizes — Many patients have difficulties with accurately reporting portion sizes, particularly for foods that are horizontally estimated (eg, spaghetti or rice on a plate) [13,14]. In particular, many patients underreport portion sizes [15]. When asking about portion sizes, using comparisons can be helpful (a deck of cards [3 ounces]; 1 cup of broccoli is about the size of a fist; 1 cup of ice cream is about the size of a tennis or racquetball) (figure 1).

Assessment tools — There are multiple assessment tools available to facilitate a more objective dietary assessment, including forms, online websites, and mobile (eg, smartphone) applications.

Forms

The following form can be used to obtain dietary information from the patient (form 1). It has the structure of a 24-hour recall and/or food frequency questionnaire.

A brief food frequency assessment can be found in the table (table 1).

An example of a food diary can be found at www.cdc.gov/healthyweight/pdf/food_diary_cdc.pdf.

Websites — Several websites supply useful dietary assessment tools. These include:

Healthy Eating Index

The Mediterranean Diet Quick Assessment Tool

National Cancer Institute Dietary Assessment Primer

Applications for mobile devices and computers — There are a number of widely available diet applications for patients to download onto their smartphones and computers [16,17]. These can be quite useful to the clinician in directing the patient to track and adjust their diet according to clinician recommendations. These applications can also help the patient to increase awareness of and compliance with healthy dietary changes. Examples include:

CalorieKing

MyFitnessPal

Sworkit

Lose It!

BEHAVIORAL ASSESSMENT — In addition to a dietary assessment, it is important to assess the key behavioral factors that are pertinent to a patient's food choices. Behavioral and life factors will impact the patient's ability to implement dietary change and can be assessed by asking about prior attempts at dietary change. Patients should be asked about their dietary environment, which includes [18]:

Work and other time constraints, including weekend differences.

Access and financial ability to buy healthy foods [19,20].

Timing of intake – Does the patient go for hours without eating and then increase intake in the evening? In patients with diabetes and prediabetes, how does timing relate to blood glucose levels and diabetic medications?

Frequency of takeout/restaurant meals, processed/prepared food, and travel.

Age and number of children living in the household.

Support of family members, including who cooks and purchases food [21].

The health of other family members.

Exercise habits.

Cultural and religious practices.

Patient's personal health goals and motivators.

Sleep, fatigue, stress.

Clinicians can then discuss simple changes in a patient's dietary environment that can improve the patient's diet. For example, if a patient has limited access to healthy foods at home, a patient can try shopping at a different grocery store and/or keeping healthy foods in sight at home. Other suggestions include bringing lunch to work or, when eating out, eating only half of the portion and/or substituting a vegetable for a starch.

Lifestyle changes, including diet and physical activity, are best accomplished with support from friends and family. When possible, all family members should follow the same diet. Change is likely to take place incrementally, building upon increasing knowledge about the impact of diet upon health concerns, and with skills developed to meet those concerns in a tasty and flavorful way [12,22].

REFERRAL — Patients with complex dietary concerns such as those with diabetes, renal disease, digestive disorders, cancer, and class III obesity should be referred to a registered dietitian for comprehensive assessment. Registered dietitians can be found through a hospital nutrition group [23], or online at eatright.org.

SOCIETY GUIDELINE LINKS — Links to society and government-sponsored guidelines from selected countries and regions around the world are provided separately. (See "Society guideline links: Healthy diet in adults".)

INFORMATION FOR PATIENTS — UpToDate offers two types of patient education materials, "The Basics" and "Beyond the Basics." The Basics patient education pieces are written in plain language, at the 5th to 6th grade reading level, and they answer the four or five key questions a patient might have about a given condition. These articles are best for patients who want a general overview and who prefer short, easy-to-read materials. Beyond the Basics patient education pieces are longer, more sophisticated, and more detailed. These articles are written at the 10th to 12th grade reading level and are best for patients who want in-depth information and are comfortable with some medical jargon.

Here are the patient education articles that are relevant to this topic. We encourage you to print or e-mail these topics to your patients. (You can also locate patient education articles on a variety of subjects by searching on "patient info" and the keyword(s) of interest.)

Basics topics (see "Patient education: Diet and health (The Basics)")

Beyond the Basics topics (see "Patient education: Diet and health (Beyond the Basics)")

SUMMARY AND RECOMMENDATIONS

Before prescribing dietary change, it is helpful to assess a number of aspects of a patient's current eating habits. Although complex patients may be referred to a dietitian for such an assessment, many patients will be adequately assessed and counseled in a primary care setting. (See 'Introduction' above and 'Dietary assessment' above.)

Most patients underreport portion sizes. When asking about portion sizes, using comparisons can be helpful (a deck of cards [3 ounces], 1 cup of broccoli is about the size of a fist, 1 cup of ice cream is about the size of a tennis or racquetball) (figure 1). (See 'Estimating portion sizes' above.)

Depending on the time available, dietary habits can be assessed quickly with a few questions, or more formally with a 24-hour dietary recall (form 1), food diary, or food frequency questionnaire (table 1). Various online tracking applications and tools are available to facilitate these assessments. (See '24-hour dietary recall' above and 'Food frequency questionnaire' above and 'Food diary' above and 'Assessment tools' above.)

Behavioral and life factors will impact the patient's ability to implement dietary change and can be assessed by asking about prior attempts at dietary change and by asking patients about their dietary environment. (See 'Behavioral assessment' above.)

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