What is the question?

• The question is: What is the relationship between frequency of meals and/or snacking and energy intake? The populations of interest for this question include young children, children, and adolescents (1 up to 19 years), and adults and older adults (19 years and older).

Why was this question asked?

• 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.

How was this question answered?

• The Committee conducted a systematic review to answer this question with support from the USDA Nutrition Evidence Systematic Review team.

What is the answer to the question?

Frequency of meals and/or snacking in children and adolescents

• A conclusion statement cannot be drawn about the relationship between frequency of meals and/or snacking in children and adolescents and energy intake because of substantial concerns with heterogeneity of exposures in a small body of evidence.  

Breakfast in adults and older adults

• A conclusion statement cannot be drawn about the relationship between breakfast consumption in adults and total daily energy intake because of substantial concerns with consistency and generalizability in the body of evidence.
• A conclusion statement cannot be drawn about the relationship between breakfast consumption in older adults and energy intake because there is no evidence available.

Number of eating occasions in adults and older adults

• A conclusion statement cannot be drawn about the relationship between number of eating occasions per day in adults and older adults and energy intake because of substantial concerns with generalizability in a small body of evidence.

Snacking in adults and older adults

• A conclusion statement cannot be drawn about the relationship between snacking in adults and older adults and energy intake because of substantial concerns with generalizability in the body of evidence.

How up-to-date is this systematic review?

• Conclusion statements from this review are based on articles published between January 2000 and May 2023.

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 energy intake?

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 outcome was energy intake 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, 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 conclusion statements and graded the strength of evidence based on its consistency, precision, risk of bias, directness and generalizability.

Results

Frequency of meals and/or snacking in children and adolescents

Conclusion statement and grade

• A conclusion statement cannot be drawn about the relationship between frequency of meals and/or snacking in children and adolescents and energy intake because of substantial concerns with heterogeneity of exposures in a small body of evidence. (Grade: Grade Not Assignable)

Summary of the evidence

• Five articles examined frequency of meals and/or snacking in children and adolescents. All were crossover randomized controlled trials.
• The articles varied in exposures and outcomes assessed. Three trials assessed breakfast consumption, 1 trial assessed snacking, and 1 trial assessed number of eating occasions. Three trials assessed energy intake at subsequent eating occasions as well as total daily energy intake, while the 2 other trials only measured energy intake at a subsequent eating occasion.

Breakfast in adults and older adults

Conclusion statement and grade

• A conclusion statement cannot be drawn about the relationship between breakfast consumption in adults and total daily energy intake because of substantial concerns with consistency and generalizability in the body of evidence. (Grade: Grade Not Assignable)

Summary of the evidence

• Nineteen articles examined breakfast in adults. Eighteen were randomized controlled trials and 1 was a prospective cohort study.
• The available evidence contributed mixed results and had many limitations including lack of diversity of the populations, different study designs, interventions, and durations as well as diversity in energy intake assessments.

Conclusion statement and grade

• A conclusion statement cannot be drawn about the relationship between breakfast consumption in older adults and energy intake because there is no evidence available. (Grade: Grade Not Assignable)  

Summary of the evidence

• No articles examined breakfast in older adults.

Number of eating occasions in adults and older adults

Conclusion statement and grade

• A conclusion statement cannot be drawn about the relationship between number of eating occasions per day in adults and older adults and energy intake because of substantial concerns with generalizability in a small body of evidence. (Grade: Grade Not Assignable)

Summary of the evidence

• Six articles examined number of eating occasions in adults and older adults. Five were randomized controlled trials and 1 was a prospective cohort study.
• The articles were not generalizable to the overall U.S. population. The trials were narrowly focused on eating occasions in the context of weight loss or weight maintenance intervention trials in populations with overweight and/or obesity or in those who had previously lost weight and would not be generalizable to a free-living U.S. population.

Snacking in adults and older adults

Conclusion statement and grade

• A conclusion statement cannot be drawn about the relationship between snacking in adults and older adults and energy intake because of substantial concerns with generalizability in the body of evidence. (Grade: Grade Not Assignable)

Summary of the evidence

• Five articles examined snacking in adults and older adults. All were randomized controlled trials.
• There is not enough evidence available to answer this question and the evidence that is available is not generalizable to the overall U.S. population. The trials were narrowly focused on snacking in the context of weight loss intervention trials in participants with overweight and/or obesity and would not be generalizable to a free-living U.S. population.

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Suggested citation: Andres A, Giovannucci E, Fisher JO, Palacios C, Raynor HA, Stanford FC, Anderson CAM, Gardner CD, Hoelscher DM, Jernigan VBB, Odoms-Young A, Callahan EH, Cole NC, Higgins M, Butera G, Terry N, Obbagy J. Frequency of Meals and/or Snacking and Energy Intake: A Systematic Review. November 2024. U.S. Department of Agriculture, Food and Nutrition Service, Center for Nutrition Policy and Promotion, Nutrition Evidence Systematic Review. Available at: https://doi.org/10.52570/NESR.DGAC2025.SR10