What is the question?

• The question is: What is the relationship between frequency of meals and/or snacking and growth, body composition, and risk of obesity? The populations of interest for this question include children and adolescents (1 up to 19 years), adults and older adults (19 years and older), and pregnancy and postpartum.

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?

Breakfast

• Regular breakfast consumption by children and adolescents may be associated with favorable outcomes related to growth, body composition, and/or lower risk of obesity. This conclusion statement is based on evidence graded as moderate.
• Breakfast skipping in adults and older adults is not associated with favorable outcomes related to body weight and composition and risk of obesity. This conclusion statement is based on evidence graded as limited.

Snacking

• Frequency of daily snacking during childhood may not be associated with outcomes related to growth, body composition, and/or risk of obesity. This conclusion statement is based on evidence graded as limited.
• Overall snacking in adults may not be associated with outcomes related to body composition and risk of obesity. However, after dinner/evening snacking in adults may be associated with less favorable outcomes related to body composition and risk of obesity. This conclusion statement is based on evidence graded as limited.
• A conclusion statement cannot be drawn about the relationship between number of eating occasions in older adults and body composition and risk of obesity because there is not enough evidence available.

Number of eating occasions

• Higher number of eating occasions per day during childhood may be associated with favorable outcomes related to growth, body composition, and/ or lower risk of obesity. This conclusion statement is based on evidence graded as limited.
• Number of eating occasions per day in adults is not associated with outcomes related to change in body composition and weight. This conclusion statement is based on evidence graded as moderate.
• A conclusion statement cannot be drawn about the relationship between number of eating occasions in older adults and body composition and risk of obesity because there is not enough evidence available.

Meal frequency

• Meal frequency/skipping by children and adolescents may not be associated with outcomes related to risk of overweight or obesity. This conclusion statement is based on evidence graded as limited.
• A conclusion statement cannot be drawn about the relationship between meal frequency/skipping by children and adolescents and growth and body composition because there is not enough evidence available.
• A conclusion statement cannot be drawn about the relationship between lunch or dinner frequency in adults and older adults and outcomes related to body composition and risk of obesity because of substantial concerns related to directness and generalizability in a small body of evidence.

Frequency of meals and/or snacking

• A conclusion statement cannot be drawn about the relationship between frequency of meals and/or snacking during pregnancy and gestational weight gain because there is not enough evidence available.
• A conclusion statement cannot be drawn about the relationship between frequency of meals and/or snacking during postpartum and postpartum weight change because there is not enough evidence available.

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 growth, body composition, and risk of obesity?

Methods

• The Committee conducted a systematic review using the methodology of the USDA NESR team. The Committee first developed a protocol. The intervention or exposure of interest was the frequency of meals and/or snacking in young children, children, adolescents, adults, older adults, and pregnancy and postpartum; definitions will vary across studies and include occasion-based measures such as meals (e.g., breakfast), snacking, and number of eating occasions. The comparator was a different frequency of meals and/or snacking. The outcomes  were growth (in young children, children, adolescents) including: height, length/stature-for-age, weight, weight-for-age, stunting, failure to thrive, wasting, BMI-for-age, weight-for-length/stature, body circumferences (arm, neck, thigh), head circumference; body composition (in young children, children, adolescents, adults, older adults) including: skinfold thickness, fat mass, ectopic fat, fat-free mass or lean mass, waist circumference, waist-to-hip-ratio; risk of obesity (in children, adolescents, adults, older adults) including: BMI, underweight, normal weight, overweight and/or obesity, weight loss and maintenance (in adults and older adults); pregnancy and postpartum-related weight change including: gestational weight gain and postpartum weight change. 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) and interventions less than 12-week duration.
• 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 conclusion statements and graded the strength of evidence based on its consistency, precision, risk of bias, directness and generalizability.

Results

Breakfast

Children and adolescents

Conclusion statement and grade

• Regular breakfast consumption by children and adolescents may be associated with favorable outcomes related to growth, body composition, and/or lower risk of obesity. This conclusion statement is based on evidence graded as moderate. (Grade: Moderate)

Summary of the evidence

• Fifty articles examined breakfast in children and adolescents.  One was a randomized controlled trial and 49 were observational studies.
• The direction of the results was similar across studies, but statistical significance and comparators being assessed were not consistent.
• The size of samples was large across studies.
• Few studies were designed and conducted well.
• The populations and interventions/exposures that were examined directly represent those of interest in this review, but the comparators do not.
• The evidence applies to the U.S. population.

Adults and older adults

Conclusion statement and grade

• Breakfast skipping in adults and older adults is not associated with favorable outcomes related to body weight and composition and risk of obesity. This conclusion statement is based on evidence graded as limited. (Grade: Limited)

Summary of the evidence

• Twenty-four articles examined breakfast in adults and older adults. Two were randomized controlled trials and 22 were observational studies.
• The statistical significance and size of effects were too different across studies.
• The size of samples was too small across studies.
• Few studies were designed and conducted well.
• The populations, interventions/exposures, comparators, and outcomes that were examined directly represent those of interest in this review.
• The evidence applies to the U.S. population, but older adults were underrepresented.

Snacking

Children and adolescents

Conclusion statement and grade

• Frequency of daily snacking during childhood may not be associated with outcomes related to growth, body composition, and/or risk of obesity. This conclusion statement is based on evidence graded as limited. (Grade: Limited)

Summary of the evidence

• Seven observational articles examined snacking in children and adolescents.
• The direction of results and size of effects were similar across studies.
• The size of samples was small is some studies.
• Few studies were designed and conducted well.
• The populations, outcomes, and comparators that were examined directly represent those of interest in this review, but the categorization and definitions of the exposures do not.
• The evidence may not apply to the U.S. population.

Adults

Conclusion statement and grade

• Overall snacking in adults may not be associated with outcomes related to body composition and risk of obesity. However, after dinner/evening snacking in adults may be associated with less favorable outcomes related to body composition and risk of obesity. This conclusion statement is based on evidence graded as limited. (Grade: Limited)

Summary of the evidence

• Twelve articles examined snacking in adults. One was a randomized controlled trial and 
  11 were observational studies.
• The direction of effects differed across studies.
• The size of samples was too small across studies.
• Few studies were designed and conducted well.
• The populations, outcomes, and comparators that were examined directly represent those of interest in this review, but the interventions/exposures do not.
• The evidence may not apply to the U.S. population.

Older adults

Conclusion statement and grade

• A conclusion statement cannot be drawn about the relationship between snacking in older adults and body composition and risk of obesity because there is not enough evidence available. (Grade: Grade Not Assignable)

Summary of the evidence

• One observational study examined snacking in older adults.
• There is not enough evidence available to answer this question.

Number of eating occasions

Children and adolescents

Conclusion statement and grade

• Higher number of eating occasions per day during childhood may be associated with favorable outcomes related to growth, body composition, and/ or lower risk of obesity. This conclusion statement is based on evidence graded as limited. (Grade: Limited)

Summary of the evidence

• Eight observational articles examined number of eating occasions in children and adolescents.
• The direction of results was similar across studies, but statistical significance differed.
• The size of samples was small in some studies.
• Few studies were designed and conducted well.
• The populations and outcomes that were examined directly represent those of interest in this review, but the interventions/exposures and comparators used do not.
• The evidence may not apply to the U.S. population.

Adults

Conclusion statement and grade

• Number of eating occasions per day in adults is not associated with outcomes related to change in body composition and weight. This conclusion statement is based on evidence graded as moderate. (Grade: Moderate)

Summary of the evidence

• Thirteen articles examined number of eating occasions in adults. Five were randomized controlled trials and 8 were observational studies.
• The direction of results and size of effects were too different across studies.
• The size of samples was small is some studies.
• Few studies were designed and conducted well.
• The populations, interventions/exposures, comparators, and outcomes that were examined directly represent those of interest in this review.
• The evidence applies to the U.S. population but may be more applicable young adults or participants with overweight or obesity.

Older adults

Conclusion statement and grade

• A conclusion statement cannot be drawn about the relationship between number of eating occasions in older adults and body composition and risk of obesity because there is not enough evidence available. (Grade: Grade Not Assignable)

Summary of the evidence

• No articles examined number of eating occasions in older adults.
• There is no evidence available to answer this question.  

Meal frequency

Children and adolescents

Conclusion statement and grade

• Meal frequency/skipping by children and adolescents may not be associated with outcomes related to risk of overweight or obesity. This conclusion statement is based on evidence graded as limited. (Grade: Limited)

Summary of the evidence

• Eleven observational articles examined meal frequency in children and adolescents and risk of overweight and obesity.
• The direction and statistical significance of results varied across studies.
• The size of samples was small in some studies.
• Few studies were designed and conducted well.
• The interventions/exposures and comparators that were examined do not directly represent those of interest in this review.
• The evidence may not apply to the U.S. population.

Conclusion statement and grade

• A conclusion statement cannot be drawn about the relationship between meal frequency/skipping by children and adolescents and growth and body composition because there is not enough evidence available. (Grade: Grade Not Assignable)

Summary of the evidence

• Five observational articles examined meal frequency in children and adolescents and growth and body composition.
• There were not enough studies that reported results in relation to growth and body composition, and therefore a conclusion statement could not be drawn.

Adults and older adults

Conclusion statement and grade

• A conclusion statement cannot be drawn about the relationship between lunch or dinner frequency in adults and older adults and outcomes related to body composition and risk of obesity because of substantial concerns related to directness and generalizability in a small body of evidence. (Grade: Grade Not Assignable)

Summary of the evidence

• Five observational articles examined meal frequency in adults and older adults.
• The evidence available to answer this question had high variability in the exposures and were unable to be synthesized together.

Frequency of meals and/or snacking

During pregnancy

Conclusion statement and grade

• A conclusion statement cannot be drawn about the relationship between frequency of meals and/or snacking during pregnancy and gestational weight gain because there is not enough evidence available. (Grade: Grade Not Assignable)

Summary of the evidence

• Two observational articles examined frequency of meals and/or snacking during pregnancy.
• There is not enough evidence available to answer this question. One article was in adolescents.

During postpartum

Conclusion statement and grade

• A conclusion statement cannot be drawn about the relationship between frequency of meals and/or snacking during postpartum and postpartum weight change because there is not enough evidence available. (Grade: Grade Not Assignable)

Summary of the evidence

• Two observational articles examined frequency of meals and/or snacking during postpartum.
• There is not enough evidence available to answer this question.

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Suggested citation: Palacios C, Raynor HA, Anderson CAM, Andres A, Fisher JO, Giovannucci E, Hoelscher DM, Gardner CD, Jernigan VBB, Odoms-Young A, Stanford FC, Callahan EH, Cole NC, Fultz A, Higgins M, Butera G, Terry N, Obbagy J. Frequency of Meals and/or Snacking and Growth, Body Composition, and Risk of Obesity: 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.SR16