Is Breakfast Really the Most Important Meal? A BMJ Review Looked at 13 Trials

“The most important meal of the day” is one of nutrition's stickiest slogans — and its origins owe as much to cereal advertising as to science, a lineage historians have traced back to James Caleb Jackson and John Harvey Kellogg in the 19th century. The modern research picture is less catchy and considerably more useful.

What the BMJ found

In 2019, Katherine Sievert and colleagues published a systematic review and meta-analysis in the BMJ examining thirteen randomized controlled trials on the effect of eating versus skipping breakfast. Their findings surprised the field:

Breakfast eaters consumed more total daily calories — roughly 260 kcal/day more on average — and had slightly higher body weight (mean difference 0.44 kg) than skippers. The commonly repeated claim that skipping breakfast causes weight gain was not supported. The review's measured conclusion: "The addition of breakfast might not be a good strategy for weight loss, regardless of established breakfast habit."

Important context: the included trials were mostly short-term and many had high or unclear risk of bias, so the authors rightly cautioned against overinterpreting the findings. What they're strong enough to retire, however, is the dogma — the idea that skipping breakfast is metabolically irresponsible regardless of context.

What the finding means in practice

For most healthy adults, morning eating is a matter of preference, hunger, and schedule — not a metabolic obligation. If you're not hungry at 7 a.m., forcing food serves no one.

The honest condition: watch what skipping does downstream. The classic failure mode is under-eating until afternoon, then inhaling whatever's nearest at 3 p.m. — vending machine archaeology, as it's known in hospital break rooms. If skipping leads to a steady lunch and sane snacks, carry on. If it leads to unplanned chaos, the morning is where to intervene.

When breakfast earns the slot

Some populations have straightforward reasons to eat early: kids heading into school, anyone training in the morning, people who wake genuinely hungry, and shift workers starting physical labor. For them the question isn't whether but what.

If you eat breakfast, make it earn the slot

The common breakfast problem isn't skipping — it's the sugar delivery systems occupying the slot. Sweetened cereals, pastries, juice-and-toast: they spike blood glucose fast and crash it before the first meeting ends. A breakfast anchored by protein — eggs, Greek yogurt, cottage cheese, oats with nuts — holds blood sugar and appetite dramatically steadier through the morning. Same time slot, fundamentally different day.

The bottom line

Breakfast is optional. If you eat it, make it protein-forward. If you skip it, guard the afternoon. And the next time a cereal box tells you it's the most important meal of the day, remember who's selling.