Frequency of Meals and/or Snacking and Consuming a Dietary Pattern Aligned with the Dietary Guidelines for Americans: A Systematic Review [Internet]

Excerpt

Background: This systematic review was conducted by the 2025 Dietary Guidelines Advisory Committee as part of the process to develop the Dietary Guidelines for Americans, 2025-2030. The U.S. Departments of Health and Human Services (HHS) and Agriculture (USDA) appointed the 2025 Dietary Guidelines Advisory Committee (Committee) in January 2023 to review evidence on high priority scientific questions related to diet and health. Their review forms the basis of their independent, science-based advice and recommendations to HHS and USDA, which is considered as the Departments develop the next edition of the Dietary Guidelines. As part of that process, the Committee conducted a systematic review with support from USDA’s Nutrition Evidence Systematic Review (NESR) team to answer the following question: What is the relationship between frequency of meals and/or snacking and consuming a dietary pattern that is aligned with the Dietary Guidelines for Americans?

Methods: The Committee conducted a systematic review using the methodology of the USDA NESR team. The Committee first developed a protocol. The interventions/exposures were frequency of meals and/or snacking in young children, children, adolescents, adults, and older adults. The comparator was a different frequency of meals and/or snacking. The outcomes were measures of diet quality as measured by the Healthy Eating Index in young children, children, adolescents, adults, and older adults. Additional inclusion criteria were established for the following study characteristics: a) use randomized or non-randomized controlled trial, prospective or retrospective cohort, or nested case-control study designs, b) be published in English in peer-reviewed journals, c) be from countries classified as high or very high on the Human Development Index, and d) enroll participants with a range of health statuses. The review excluded studies that only examine frequency of intake of a single food, beverage or category of foods and/or beverages (e.g., frequency of cereal consumption, frequency of dairy consumption, frequency of snack foods).

NESR librarians conducted a literature search in PubMed, Embase, CINAHL, and Cochrane to identify articles published between January 2000 and May 2023. Two NESR analysts independently screened all electronic results and the reference lists of included articles based on the pre-determined criteria.

NESR analysts extracted data, from each included article, with a second analyst verifying accuracy of the extraction. Two NESR analysts independently conducted a formal risk of bias assessment, by study design, for each included article, then reconciled any differences in the assessment. The Committee qualitatively synthesized the evidence, according to the synthesis plan, with attention given to the overarching themes or key concepts from the findings, similarities and differences between studies, and factors that may have affected the results. The Committee developed a conclusion statement and graded the strength of evidence based on its consistency, precision, risk of bias, directness and generalizability.

Results: Conclusion statement and grade: A conclusion statement cannot be drawn about the relationship between frequency of meals and/or snacking and consuming a dietary pattern that is better aligned with the Dietary Guidelines for Americans because there is not enough evidence available. (Grade: Grade Not Assignable)

Summary of the evidence:

1. Two articles met the inclusion criteria for this review. Both were prospective cohort studies.

2. There was not enough evidence available to answer this question. Two included articles assessed breakfast and no articles with other categories of frequency of meals were included. The articles had inconsistent results and were in very specific populations (10th graders; military recruits).