Scientific Questions

The 2025 Dietary Guidelines Advisory Committee (Committee) is using three scientific approaches (data analysis, food pattern modeling, and systematic reviews) to examine the evidence on nutrition and health. As part of Step 1, HHS and USDA developed a list of proposed scientific questions to inform the Committee’s work. The Committee prioritized the questions and presented the list of questions it planned to address at Meeting 2. According to the Federal Advisory Committee Act, the Committee has up to two years to complete its work. Similar to all previous Committees, as the Committee conducts its work, it has taken steps to further prioritize the scientific questions to be reviewed to inform its advice to HHS and USDA in the time available to conduct its work.

The Committee is divided into subcommittees to conduct its evidence review, and the scientific questions being addressed by each subcommittee are listed below. In addition, a list of scientific questions that the Committee has discontinued work on is provided, with the rationale for why each question was deprioritized.

During its Committee Meetings, the Committee discusses progress made on its work to answer the scientific questions prioritized for review. Presentations are made by each subcommittee documenting the evidence review and synthesis for each question and draft conclusion statements are shared for discussion. The first draft conclusion statements were shared with the Committee starting with Meeting 3 and additional conclusions statements were presented at subsequent meetings. Visit the 2025 Dietary Guidelines Advisory Committee Meetings pages to find more information about the Committee’s work, and attend future meetings to hear updates on the Committee’s work.

All of the protocols that describe the plan for how each scientific question is being examined using systematic review or food pattern modeling are available through the links below. The data analysis plan outlines the process, strategy and analyses being used to answer the data analysis questions.

View Systematic Review Protocols View Food Pattern Modeling Protocols View Data Analysis Plan

Subcommittee 1: Dietary Patterns and Specific Dietary Pattern Components Across Life Stages

Systematic Review Questions:

Dietary Patterns

What is the relationship between dietary patterns consumed and growth, body composition, and risk of obesity?

What is the relationship between dietary patterns consumed and risk of cardiovascular disease?

What is the relationship between dietary patterns consumed and risk of type 2 diabetes?

What is the relationship between consumption of dietary patterns with varying amounts of ultra-processed foods and growth, body composition, and risk of obesity?

What is the relationship between dietary patterns consumed and risk of breast cancer?

What is the relationship between dietary patterns consumed and risk of colorectal cancer?

What is the relationship between dietary patterns consumed and risk of cognitive decline, dementia, and Alzheimer's disease?

Beverages

What is the relationship between beverage patterns consumed and growth, body composition, and risk of obesity?

What is the relationship between dairy milk and milk alternative consumption and growth, body composition, and risk of obesity?

What is the relationship between 100% juice consumption and growth, body composition, and risk of obesity?

What is the relationship between sugar-sweetened beverage consumption and growth, body composition, and risk of obesity?

What is the relationship between low- and no-calorie sweetened beverage consumption and growth, body composition, and risk of obesity?

What is the relationship between sugar-sweetened beverage consumption and risk of type 2 diabetes?

What is the relationship between low- and no-calorie sweetened beverage consumption and risk of type 2 diabetes?

Food Sources

What is the relationship between food sources of saturated fat consumed and risk of cardiovascular disease?

Subcommittee 2: Diet in Pregnancy and Birth through Adolescence

Systematic Review Questions:

What is the relationship between dietary patterns consumed during pregnancy and risk of hypertensive disorders of pregnancy?

What is the relationship between dietary patterns consumed during pregnancy and risk of gestational diabetes mellitus?

What is the relationship between repeated exposure to foods and food acceptance?

What is the relationship between complementary feeding and growth, body composition, and risk of obesity?

What is the relationship between parental and caregiver feeding styles and practices during childhood and growth, body composition, and risk of obesity?

What is the relationship between parental and caregiver feeding styles and practices during childhood and consuming a dietary pattern that is aligned with the Dietary Guidelines for Americans?

What is the relationship between dietary patterns consumed during pregnancy and gestational age at birth?

What is the relationship between dietary patterns consumed during pregnancy and birth weight?

Subcommittee 3: Food Pattern Modeling and Data Analysis

Food Pattern Modeling Questions:

Overarching Question: Considering each life stage, should changes be made to the USDA Dietary Patterns (Healthy U.S.-Style, Healthy Mediterranean-Style, and/or Healthy Vegetarian)? And, should additional Dietary Patterns be developed/proposed?

The following food pattern modeling analyses will be evaluated by the Committee in support of answering the overarching question:

Should foods and beverages with lower nutrient density (i.e., those with added sugars, saturated fat, and sodium) contribute to item clusters, representative foods, and therefore the nutrient profiles for each food group and subgroup used in modeling the USDA Dietary Patterns?
What are the differences between nutrient profiles calculated using the dietary intakes of the total U.S. population and population groups?
What are the implications for nutrient intakes when modifying the Protein Foods group and subgroup quantities within the Healthy U.S.-Style Dietary Pattern or Healthy Vegetarian Dietary Pattern? What are the implications for nutrient intakes when proportions of animal-based Protein Foods subgroups are reduced and proportions of plant-based Protein Foods subgroups are increased?
What are the implications for nutrient intakes when modifying the Dairy and Fortified Soy group quantities within the Healthy U.S.-Style Dietary Pattern? What are the implications for nutrient intakes when Dairy food and beverage sources are replaced with non-Dairy alternatives?
What are the implications for nutrient intakes when modifying the quantities of the Grains group within the Healthy U.S.-Style Dietary Pattern? What are the implications for nutrient intakes when specific individual staple grains are emphasized; or when the Grains group is replaced with other staple carbohydrate foods (i.e., Starchy Vegetables; Beans, Peas, and Lentils; starchy Red and Orange vegetables)?
What are the implications for nutrient intakes when modifying the Vegetables food group and subgroup quantities within the Healthy U.S.-Style Dietary Pattern?
What are the implications for nutrient intakes when modifying the Fruits food group quantities within the Healthy U.S.-Style Dietary Pattern?
Can nutrient goals be met when animal sources of foods and beverages are removed from the Healthy Vegetarian Dietary Pattern for ages 2 years and older?
What quantities of foods and beverages lower in nutrient density can be accommodated in the USDA Dietary Patterns while meeting nutritional goals within calorie levels?
Do simulated diets that meet the updated USDA Dietary Patterns and reflect variation in dietary intakes achieve nutrient adequacy?
Can nutrient goals be met when carbohydrate-containing foods and beverages are reduced in the Healthy U.S.-Style Dietary Pattern for ages 2 years and older?

Data Analysis Questions:

What are the current patterns of food and beverage intake?

What are the current intakes of food groups, nutrients, and dietary components?

What is the current prevalence of nutrition-related chronic health conditions?

Which nutrients and/or dietary components present a substantial public health concern because of underconsumption or overconsumption?

Subcommittee 4: Strategies for Individuals and Families Related to Diet Quality and Weight Management

Systematic Review Questions:

What is the relationship between frequency of meals and/or snacks and growth, body composition, and risk of obesity?

What is the relationship between frequency of meals and/or snacks and energy intake?

What is the relationship between frequency of meals and/or snacks and consuming a dietary pattern that is aligned with the Dietary Guidelines for Americans?

What is the relationship between portion size and growth, body composition, and risk of obesity?

What is the relationship between portion size and energy intake?

Evidence Scan Questions:

What evidence has been published on the relationship between culturally tailored dietary interventions and diet-related psychosocial factors, dietary intake, diet quality, and health outcomes?

Discontinued Scientific Questions

Subcommittee 1: Dietary Patterns and Specific Dietary Pattern Components Across Life Stages
Systematic Review Questions:	Rationale
Dietary Patterns
What is the relationship between dietary patterns consumed and risk of depression?	The Committee consulted Federal subject matter experts on this topic and based on concerns from these experts about reverse causality and/or the plausibility of the relationship between dietary patterns and risk of depression, the Committee decided to discontinue this systematic review.
What is the relationship between dietary patterns consumed and risk of prostate cancer?	In consideration of project workload and timelines, the Committee discontinued this systematic review after determining it was lower priority due to there being fewer new studies published on this topic compared to dietary patterns and breast cancer or colorectal cancer.
What is the relationship between dietary patterns consumed and bone health?	In consideration of project workload and timelines, the Committee discontinued this systematic review after determining it was lower priority due to there being fewer new studies published on this topic since the previous reviews conducted by the 2015 and 2020 Dietary Guidelines Advisory Committees.
Beverages
What is the relationship between coffee and/or tea consumption and risk of type 2 diabetes?	In consideration of project workload and timelines, the Committee discontinued this systematic review after determining that assessing the overall dietary pattern in relation to risk of type of 2 diabetes is higher priority than examining coffee and tea independently. In addition, the nutritional implications of consuming this beverage type are being examined in other systematic reviews and food pattern modeling analyses.
What is the relationship between coffee and/or tea consumption and growth, body composition, and risk of obesity?	In consideration of project workload and timelines, the Committee discontinued this systematic review after determining that assessing the overall dietary pattern in relation to growth, body composition, and risk of obesity is higher priority than examining coffee and tea independently. In addition, the nutritional implications of consuming this beverage type are being examined in other systematic reviews and food pattern modeling analyses.
What is the relationship between dairy milk and milk alternative consumption and risk of type 2 diabetes?	In consideration of project workload and timelines, the Committee discontinued this systematic review after determining that assessing the overall dietary pattern in relation to risk of type of 2 diabetes is higher priority than examining dairy milk and milk alternatives independently. In addition, the nutritional implications of consuming this beverage type are being examined in other systematic reviews and food pattern modeling analyses.
What is the relationship between 100% juice consumption and risk of type 2 diabetes?	In consideration of project workload and timelines, the Committee discontinued this systematic review after determining that assessing the overall dietary pattern in relation to risk of type of 2 diabetes is higher priority than examining 100% juice independently. In addition, the nutritional implications of consuming this beverage type are being examined in other systematic reviews and food pattern modeling analyses.

Subcommittee 4: Strategies for Individuals and Families Related to Diet Quality and Weight Management
Evidence Scan Question:	Rationale
What evidence has been published on the relationship between home food availability in adults and diet-related psychosocial factors, dietary intake, diet quality, and health outcomes?	In consideration of project workload and timelines, the Committee discontinued this evidence scan after determining that the planned evidence scan on culturally tailored dietary interventions is higher priority. In addition, home food availability in infants, young children, children, and adolescents will be examined in other systematic reviews being conducted on caregiver feeding practices.