GradedHealth

Breakfast

Last reviewed October 2026 · Based on 11 studies

Bottom line

Eating breakfast is linked to lower heart-disease risk in large observational studies, which cannot prove cause. Trials find breakfast does not help you lose weight, and skipping it does not slow metabolism; in short trials, skipping raised LDL cholesterol slightly.

What it helps with

  • Helps you lose weight — No effect, evidence grade C (Limited). Two meta-analyses of short trials (486 and 425 people); downgraded for small total sample and high risk of bias. Both lean slightly toward skipping, not gaining.
  • Speeds up your metabolism — No effect, evidence grade C (Limited). One six-week trial of 33 lean adults; downgraded for small sample size.
  • Lowers 'bad' LDL cholesterol — Benefit, evidence grade C (Limited). Meta-analysis of seven RCTs (425 people), but LDL came from only three; downgraded for small total sample and surrogate marker.
  • Lowers the risk of heart disease and stroke — Benefit, evidence grade C (Limited). Observational cohorts only; large (about 220,000 to 240,000 people) but sensitivity analyses are inconsistent and the design cannot show cause; downgraded for inconsistency.
  • Lowers the risk of early death — Benefit, evidence grade C (Limited). Observational cohorts only; two meta-analyses agree in direction but are inconsistent (I2 77%) and cannot show cause; downgraded for inconsistency and design.
  • Helps children's attention and memory — Benefit, evidence grade C (Limited). Systematic review of 45 mostly acute, small studies with inconsistent results and industry-linked funding; downgraded for inconsistency and small samples.
  • Lowers the risk of overweight and obesity — Mixed results, evidence grade C (Limited). Mostly observational studies, which point to benefit, while trials show no weight benefit; mixed direction, downgraded for observational design and inconsistency.

What it is

In research, breakfast means a morning meal compared with skipping it [1]. In the Bath trial, the breakfast was at least 700 kcal eaten before 11am [2].

What the research says

Trials find little weight benefit from breakfast. Thirteen randomised trials pooled in one meta-analysis found that the seven weight trials gave skippers about 0.44 kg less weight (95% CI 0.07 to 0.82) [1]. A second meta-analysis of seven trials found about 0.54 kg less weight with skipping [3]. Breakfast eaters took in about 260 kcal a day more across ten trials, with wide variation between studies [1].

In a six-week trial of 33 lean adults, breakfast did not change resting metabolism compared with fasting until noon [2]. Skipping breakfast raised LDL cholesterol by about 9 mg/dL in the three trials that measured it [3].

Observational studies link skipping breakfast with higher cardiovascular risk [4] and with overweight [5], but they cannot show cause. In children, breakfast compared with fasting more reliably improved attention, executive function and memory in the short term [6].

Doses used in studies

The Bath trial gave at least 700 kcal of breakfast before 11am every day for six weeks; the fasting arm ate nothing until noon [2]. The weight trials averaged about seven weeks, and the energy-intake trials about two weeks [1]. The seven trials of breakfast and LDL averaged about 8.6 weeks [3].

Safety and interactions

The trials reviewed here measured weight, energy intake and blood markers, not side effects, medicine interactions or pregnancy [1][3]. Ask a doctor before changing your eating pattern if you take medicines for diabetes or blood pressure, or if you are pregnant.

Caveats and open questions

The weight trials were short and mostly of low quality, with a high or unclear risk of bias [1]. The heart and early-death findings come only from observational studies and cannot show that breakfast protects anyone [4][7]. The metabolism finding rests on one trial of 33 people [2]. The children's evidence comes from a review partly funded by Kellogg's USA [6].

References

  1. Effect of breakfast on weight and energy intake: systematic review and meta-analysis of randomised controlled trials.. BMJ, 2019.
  2. The causal role of breakfast in energy balance and health: a randomized controlled trial in lean adults.. Am J Clin Nutr, 2014.
  3. Breakfast Skipping, Body Composition, and Cardiometabolic Risk: A Systematic Review and Meta-Analysis of Randomized Trials.. Obesity (Silver Spring), 2020.
  4. Association between skipping breakfast and risk of cardiovascular disease and all cause mortality: A meta-analysis.. Clin Nutr, 2020.
  5. Skipping breakfast is associated with overweight and obesity: A systematic review and meta-analysis.. Obes Res Clin Pract, 2020.
  6. The Effects of Breakfast and Breakfast Composition on Cognition in Children and Adolescents: A Systematic Review.. Adv Nutr, 2016.
  7. Breakfast skipping and risk of all-cause, cardiovascular and cancer mortality among adults: a systematic review and meta-analysis of prospective cohort studies.. Food Funct, 2024.