Snacks: the evidence depends on who is eating and when

The word snack covers an apple and a bag of chips alike, so the useful evidence is about who eats one and when. The strongest trial data come from people who are ill. In a meta-analysis of 8 controlled studies in 341 patients with liver cirrhosis, a late evening snack improved albumin, ammonia and prothrombin time, with effect sizes of 0.233, -0.425 and -0.589. The studies were small, the abstract gives no confidence intervals, and the Child-Pugh score did not change. In children aged 5 to 18 with overweight, five randomized programs that cut unhealthy snacks alongside more fruit and vegetables, daily activity and less screen time were linked to a smaller waist (SMD -0.54, 95% CI -1.06 to -0.03). Snack cutting was one part of each program, so the result cannot be credited to it alone, and the interval comes close to zero. For healthy adults we found no trials, only observation. A 2024 USDA review of 6 observational articles found snacking after dinner or in the evening more consistently tied to less favorable body composition and obesity risk, and the quality of those snacks was unknown.

The numbers, per 3.5 oz (100 g)

What a real portion looks like

• US children and adolescents who snack get 27% of their daily energy and 42% of their added sugar from snacks, per NHANES 2017 to March 2020. — US children and adolescents aged 2 to 19 years who snack, WWEIA NHANES 2017 to March 2020 Evidence C source
  27% of energy, 42% of added sugar from snacks

What your body absorbs

• Laboratory and absorption data suggest iron in plant-based snacks is less available because of phytate, polyphenols, tannins and oxalic acid, while vitamin C or fermentation can improve it. — Not a population finding: review discussion of iron bioavailability in snack formulations Evidence D source
  Direction only, no size reported
• In one trial within a review of iron-rich snacks, a plant-based snack (laddu) did not raise hemoglobin in adolescent girls, which the authors put down to low iron bioavailability. — Adolescent girls aged 10 to 19 years, one RCT (Patil 2014) within the review Evidence C source
  No significant change in Hb concentration

What cooking and storage change

• Food science studies reviewed in 24 articles show that frying changes potato chips by making them absorb fat, and crispness depends on moisture and frying conditions. — Not a human population: 24 food science articles on potato chips (n = 24 articles) Evidence D source
  Direction only, fat uptake size not reported in abstract

What it does to your health

• In a meta-analysis of 8 controlled trials in 341 patients with liver cirrhosis, a late evening snack improved albumin (effect size 0.233), ammonia (-0.425) and prothrombin time (-0.589). — Patients with liver cirrhosis, with or without hepatocellular carcinoma, 8 studies (n = 341) Evidence B source
  Effect sizes: albumin 0.233, ammonia -0.425, prothrombin time -0.589; no significant effect on Child-Pugh score
• In a meta-analysis of randomized trials in children aged 5 to 18 with overweight, five behavioral programs that included cutting unhealthy snacks were linked to smaller waist circumference (SMD -0.54). — Children aged 5 to 18 years with overweight or obesity, 34 RCTs in total, 5 in this subgroup (n = 8183) Evidence A source
  SMD -0.54 (95% CI -1.06 to -0.03) for waist circumference
• In a systematic review of 10 trials in adolescent girls, nine found that iron-rich food-based snacks raised hemoglobin by 0.45 to 2.28 g/dL. — Apparently healthy adolescent girls aged 10 to 19 years, 10 studies with 24 to 211 participants each (n = 24-211 per study) Evidence B source
  Hb increase 0.45 to 2.28 g/dL in 9 of 10 studies
• Observational data link frequent snack intake in preschool children with higher odds of recurrent respiratory infections (OR 1.61) across 12 studies. — Preschool children, 12 observational studies (n = 170915) Evidence C source
  OR 1.61 (95% CI 1.35 to 1.92)
• Observational data from 600 Iranian adolescents link low-quality snacks with 1.13 times higher decayed, missing and filled teeth scores. — 600 adolescents, Kerman, southeast Iran (n = 600) Evidence C source
  DMFT 1.13 times higher with low-quality vs high-quality snacks
• In 87 college students followed for 12 weeks, any intake of ultra-processed snacks was associated with a rise in BMI (beta 0.280). — College students aged 18 to 24, Snackability trial participants (n = 87) Evidence C source
  Beta 0.280, p < 0.05 for BMI change over 12 weeks
• A 2024 USDA evidence review found after dinner or evening snacking more consistently tied to less favorable body composition in adults than snacking overall. — Adults, 6 observational articles on evening snacking (n = 6 articles) Evidence C source
  4 of 6 articles reported at least one unfavorable association

Safety, limits and interactions

• US FDA health claim wording states that frequent eating of foods high in sugars and starches as between-meal snacks can promote tooth decay. — General population, US labeling rule Evidence E source
  Regulatory statement, no effect size

What people believe that the data does not support

• Observational data link packaged savory snacks with slightly lower type 2 diabetes risk (RR 0.92), while ultra-processed food overall carried RR 1.48 in 12 cohorts. — 12 prospective cohort studies, Europe, North America, Korea, Brazil, Australia (n = 714199) Evidence C source
  Packaged savory snacks RR 0.92 (95% CI 0.88 to 0.95); all UPF highest vs lowest RR 1.48 (1.36 to 1.61)
• The EU refused to authorize a claim that hypo-caloric snacks reduce abdominal fat cell size during a low-calorie diet. — EU labeling Evidence E source
  Non-authorized
• The EU refused to authorize a claim that a low-calorie filling snack with slow carbohydrates keeps blood sugar even and eases weight control. — EU labeling Evidence E source
  Non-authorized

What is still unknown

• A meta-analysis of observational studies in adolescents found no significant link between a snacks dietary pattern and depressive symptoms (OR 1.20). — Children and adolescents with mean age 19 or less, 21 observational studies Evidence C source
  OR 1.20 (95% CI 0.70 to 1.48), not significant
• The same USDA review found no link between snacking and body composition or obesity in 5 of 7 articles on children and adolescents. — Children and adolescents, 7 observational articles (n = 7 articles) Evidence C source
  5 of 7 null
• For older adults the USDA review could not grade the evidence on snacking and obesity, because only one article had a mean age above 60. — Older adults (n = 1 article) Evidence C source
  Grade not assignable

The bottom line

Among US children and adolescents who snack, snacks supplied 27% of daily energy and 42% of added sugar in NHANES 2017 to March 2020, based on one day of dietary recall. Frequent cookies, brownies and sweetened drinks account for much of that sugar. What goes into the snack matters. In a review of 10 trials in apparently healthy adolescent girls, nine found that iron-rich food-based snacks raised hemoglobin by 0.45 to 2.28 g/dL. Half of those trials were quasi-experiments, nine carried a moderate risk of bias, and the results were never pooled. One plant-based snack, a laddu, produced no significant change, which the authors put down to poorly absorbed iron without measuring it. Laboratory and absorption studies suggest phytate, polyphenols, tannins and oxalic acid hold back iron from plant snacks, and vitamin C or fermentation can improve it. Frying makes potato chips absorb fat, according to 24 food science studies whose summary gives no amount. The observational signals are small and hard to separate from lifestyle. Preschool children with frequent snack intake had 1.61 times the odds of recurrent respiratory infections (95% CI 1.35 to 1.92) across 12 studies. In 600 adolescents in one Iranian city, low-quality snacks went with tooth decay scores 1.13 times higher, in a single cross-sectional survey. In 87 college students followed for 12 weeks, any ultra-processed snack intake was associated with a rise in BMI (beta 0.280), using self-reported weight. One finding runs against the usual story. In 12 cohorts with 714,199 people, ultra-processed food overall went with a higher type 2 diabetes risk (RR 1.48, 95% CI 1.36 to 1.61), while packaged savory snacks went with a slightly lower one (RR 0.92, 0.88 to 0.95). That subgroup came from only three publications and stays open to confounding. The EU refused a claim that hypo-caloric snacks shrink abdominal fat cells on a low-calorie diet, and another that a filling low-calorie snack keeps blood sugar even and eases weight control. A refusal means the evidence was not enough when it was assessed. Who should be careful. The US labeling rule on sweeteners states that frequent eating of foods high in sugars and starches as between-meal snacks can promote tooth decay. For children that sits beside the US figure above, where 42% of their added sugar arrives at snack time. The cirrhosis finding comes from patients under medical care and says nothing about people without liver disease. Several questions stay open. A meta-analysis of 21 observational studies found no significant link between a snacks eating pattern and depressive symptoms in young people (OR 1.20, 95% CI 0.70 to 1.48), with high heterogeneity. The USDA review found no association between snacking and body composition in 5 of 7 articles on children and adolescents, which defined a snack in different ways. For adults over 60 it could not grade the evidence at all, because only one article had a mean age above 60.

Sources

1. snk-daily-r1-15 · dietary survey brief
   Snacks account for 27% of total energy intake of children and adolescent snack consumers. As Figure 5 illustrates, snacks contribute around one-quarter or less of daily intake for most nutrients. Notably, forty-two percent of total added sugar intake is consumed at snacks, which is explained by frequent intake of cookies/brownies and sweetened beverages (See table 2, page 6).
   USDA FSRG Dietary Data Briefs, WWEIA NHANES 2017-March 2020 · checked 2026-09-28
2. snk-daily-r1-04 · review discussion
   In contrast, the iron bioavailability of plant-based snacks is limited due to the presence of potent iron absorption inhibitors, such as phytate, polyphenols, tannins, and oxalic acid [38]. To improve iron bioavailability in plant-based snacks, incorporation of iron absorption enhancers (vitamin C or animal tissues), use of traditional food processing methods such as fermentation, malting, soaking, thermo processing, and the addition of enzymes such as phytase have also been proven effective [[39], [40], [41], [42], [43]].
   Adv Nutr, 2025 · checked 2026-09-28
3. snk-daily-r1-05 · systematic review of trials
   Generally, 1 RCT by Patil et al. [29] (2014) among the shortlisted studies on the efficacy of an iron-rich snack (laddu) was not found to be efficacious in increasing the Hb concentration among study participants, with no significant change in Hb concentration. The conclusion drawn was that the lack of efficacy in raising Hb concentration may be attributed to the lower bioavailability of iron in the food vehicle-laddu.
   Adv Nutr, 2025 · checked 2026-09-28
4. snk-daily-r1-06 · systematic review of lab studies
   This process changes the nutritional value and structure of the product by absorbing fat into the product.
   J Texture Stud, 2026 · checked 2026-09-28
5. snk-daily-r1-01 · meta-analysis
   Our analysis included eight studies comprising 341 patients (167 in LES groups and 174 in control groups). ... These eight studies demonstrated that LES intervention had significant effects for liver biochemical parameters on albumin, ammonia, and prothrombin time, with respective effect sizes of 0.233, -0.425, and -0.589
   J Gastroenterol Hepatol, 2019 · checked 2026-09-28
6. snk-daily-r1-02 · meta-analysis of RCTs
   Five additional RCTs involved behavioral interventions on dietary education to reduce unhealthy snacks, increase fruit and vegetable intake, promote daily physical activity, and limit screen time, supported by online resources also showed a significant association with WC (SMD, -0.54 [95% CI, -1.06 to -0.03]).
   JAMA Netw Open, 2025 · checked 2026-09-28
7. snk-daily-r1-03 · systematic review of trials
   Ten studies (five RCTs and five quasi-experiments) involving 24 to 211 participants were included. ... Iron content of snacks varied, with nine studies out of ten reported Hb increases ranging from 0.45 to 2.28 g/dL.
   Adv Nutr, 2025 · checked 2026-09-28
8. snk-daily-r1-08 · meta-analysis of observational studies
   A total of 12 studies involving 170 915 children were included. Meta-analysis showed that asthma (OR = 3.26, 95% CI: 1.85-5.7), passive smoking (OR = 1.50, 95% CI: 1.20-1.87) and frequent snack intake (OR = 1.61, 95% CI: 1.35-1.92) were significant risk factors for RRTI in preschool children.
   J Paediatr Child Health, 2026 · checked 2026-09-28
9. snk-daily-r1-10 · cross-sectional
   Results: DMFT score of adolescents who consumed low-quality snacks were 1.13 times more than those who consumed high-quality snacks.
   Nutr Health, 2026 · checked 2026-09-28
10. snk-daily-r1-11 · longitudinal observational
    For the longitudinal analysis, 87 participants submitted the weight and height after 12 wk, and we found that any intake of ultra-processed snacks was associated with an increase in BMI after 12 wk (β = 0.280, p < 0.05).
    J Am Coll Health, 2026 · checked 2026-09-28
11. snk-daily-r1-12 · agency systematic review
    When isolating the 6 articles that only looked at snacking after dinner or in the evening, there was a much more consistent association between snacking at this time and less favorable body composition and risk of obesity outcomes.
    USDA Nutrition Evidence Systematic Review, Frequency of Meals and/or Snacking and Growth, Body Composition, and Risk of Obesity, 2024 · checked 2026-09-28
12. snk-daily-r1-16 · regulation
    (v) Frequent eating of foods high in sugars and starches as between-meal snacks can promote tooth decay.
    21 CFR 101.80, Health claims: dietary noncariogenic carbohydrate sweeteners and dental caries · checked 2026-09-28
13. snk-daily-r1-07 · meta-analysis of cohorts
    Comparing the highest vs. lowest categories of intake, summary RR for T2DM risk was 1.48 (95% CI, 1.36 to 1.61). ... Among individual UPF subgroups, processed meats (summary RR, 1.34; 95% CI, 1.16 to 1.54) were positively associated, whereas ultra-processed cereals and breads (0.98; 95% CI, 0.97 to 0.99) and packaged savory snacks (0.92; 95% CI, 0.88 to 0.95) were inversely associated.
    Diabetes Metab J, 2025 · checked 2026-09-28
14. snk-daily-r1-17 · regulatory register
    POL-HC-6217 “Hypo-caloric snacks (KOT products)” Contributes to reduce the adipocytes size at the abdominal level, in the context of a low-calorie diet -/- Non-authorised
    EU Register on nutrition and health claims, claim POL-HC-6217, snapshot 2026-09-21 · checked 2026-09-28
15. snk-daily-r1-18 · regulatory register
    POL-HC-7136 Fructose + dextrose Low-calorie and filling snack. Slow carbohydrates prevent rapid changes in blood sugar. Slow carbohydrates help to keep blood sugar levels even for a long time. With no rapid drops in blood sugar people feel more satiated, due to which weight control is easier. Fibre-rich food is good for those wanting to lose weight. Fibre does not contain energy, but is filling. Non-authorised
    EU Register on nutrition and health claims, claim POL-HC-7136, snapshot 2026-09-21 · checked 2026-09-28
16. snk-daily-r1-09 · meta-analysis of observational studies
    There was no statistically significant association between depressive symptoms and "unhealthy" and "snacks" patterns (OR: 1.20 [95% CI: 0.95, 1.46]; OR: 1.20 [95% CI: 0.70, 1.48]) dietary patterns.
    Nutr Rev, 2025 · checked 2026-09-28
17. snk-daily-r1-13 · agency systematic review
    Five out of 7 articles reported that there was no association between snacking and body composition and risk of obesity outcomes.
    USDA Nutrition Evidence Systematic Review, Frequency of Meals and/or Snacking and Growth, Body Composition, and Risk of Obesity, 2024 · checked 2026-09-28
18. snk-daily-r1-14 · agency systematic review
    Only one of the articles65 had a mean age of >60 years and therefore the evidence was only generalizable to adults. A grade not assignable conclusion statement was formed for the relationship between snacking and body composition and risk of obesity in older adults.
    USDA Nutrition Evidence Systematic Review, Frequency of Meals and/or Snacking and Growth, Body Composition, and Risk of Obesity, 2024 · checked 2026-09-28