GradedHealth

Does skipping breakfast slow your metabolism or make you gain weight?

Trials find skipping breakfast does not slow metabolism or add weight. Heart and death links come from studies that cannot prove cause.

Published October 2026

Short answer

Trials find no metabolic slowdown and no weight gain from skipping breakfast. The evidence is limited, and the heart and death links are observational. Evidence grade C (Limited). Meta-analyses of short, low-quality trials (486 people for weight); downgraded for small sample size and high risk of bias.

Key takeaways

  • Pooled trials found people who skipped breakfast weighed about 0.4 kg less, not more [1].
  • Eating breakfast did not change resting metabolism over six weeks in a trial of 33 lean adults [2].
  • In the pooled trials, breakfast eaters took in about 260 kcal a day more, but the trials were short and inconsistent [1].
  • Skipping breakfast was linked to higher heart disease and early-death risk in cohort studies, which cannot prove cause [3][4].
  • In short trials, skipping breakfast raised LDL 'bad' cholesterol by about 9 mg/dL [5].

The short version

Skipping breakfast does not appear to slow your metabolism or make you gain weight [2][1]. In controlled trials, people who skipped breakfast weighed slightly less, not more, but the trials were short and mostly of low quality [1]. The heart and early-death links come from observational studies, which cannot prove that skipping breakfast causes them [3][4].

What the studies show

A meta-analysis pooled 13 randomised trials of breakfast in adults from high-income countries [1]. Seven of them measured weight, with 486 people in total. Skippers weighed about 0.44 kg less on average, a small gap with a range of 0.07 to 0.82 kg [1]. A second meta-analysis of seven trials, with 425 people, found about 0.54 kg less weight with skipping [5].

Breakfast eaters took in more food. Across ten trials, people told to eat breakfast ate about 260 kcal a day more than those told to skip it, though results varied widely between trials [1].

On metabolism, the Bath Breakfast Project randomised 33 lean adults to eat at least 700 kcal before 11am every day, or to fast until noon, for six weeks [2]. Resting metabolic rate, the calories the body burns at rest, stayed stable within 11 kcal a day, so skipping breakfast did not slow it down [2]. Physical activity burned about 442 kcal a day more with breakfast, and the breakfast group ate about 539 kcal a day more [2]. Body weight did not differ between the groups by the end of the trial [2].

Observational studies point the other way. Seven cohort studies with about 222,000 people linked skipping breakfast to a 22% higher risk of cardiovascular disease and a 25% higher risk of death from any cause [3]. Nine cohorts with about 242,000 people found a similar pattern, with higher risks of cardiovascular and cancer death [4]. In a US cohort of 6,550 adults followed for 17 to 23 years, people who never ate breakfast had 1.87 times the cardiovascular death risk of daily breakfast eaters; the all-cause difference was not statistically significant [6].

Skipping breakfast was also linked to overweight. In cohort studies, people who ate breakfast on few days a week had a 44% higher risk of overweight or obesity [7].

Skipping breakfast also raised LDL ('bad') cholesterol. Three of the seven trials measured it, and LDL was about 9 mg/dL higher in people who skipped breakfast [5].

In children, breakfast helped some thinking tests in the short term. Compared with fasting, breakfast more reliably helped attention, executive function and memory, and the effects were more visible in undernourished children [8].

The nuances

Most trials were short. The weight trials averaged about seven weeks, and the energy-intake trials about two weeks [1]. All of the included trials had a high or unclear risk of bias in at least one area [1]. That is why the trial findings are limited, not settled.

Only 5.1% of the US cohort never ate breakfast, so the heart result rests on a small group [6].

The children's review was partly funded by a grant from Kellogg's USA to its authors [8]. Its authors could not draw firm conclusions about breakfast composition or school breakfast programmes, which had too few studies [8].

What this means for you

The trials suggest that skipping breakfast on its own is unlikely to slow your metabolism or add weight [2][1]. Eating breakfast does not appear to help with weight loss either [1]. The heart findings are observational, so they cannot show that breakfast protects your heart [3]. If heart health is a concern, talk with your doctor about your cholesterol, blood pressure and overall diet. Ask a doctor before changing how you eat if you take medicines for diabetes or blood pressure, or if you are pregnant.

Go deeper

  • Breakfast — Eating breakfast is linked to lower heart-disease risk in large observational studies, which cannot prove cause.

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. Association between skipping breakfast and risk of cardiovascular disease and all cause mortality: A meta-analysis.. Clin Nutr, 2020.
  4. 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.
  5. Breakfast Skipping, Body Composition, and Cardiometabolic Risk: A Systematic Review and Meta-Analysis of Randomized Trials.. Obesity (Silver Spring), 2020.
  6. Association of Skipping Breakfast With Cardiovascular and All-Cause Mortality.. J Am Coll Cardiol, 2019.
  7. Skipping breakfast is associated with overweight and obesity: A systematic review and meta-analysis.. Obes Res Clin Pract, 2020.
  8. The Effects of Breakfast and Breakfast Composition on Cognition in Children and Adolescents: A Systematic Review.. Adv Nutr, 2016.