Breakfast is the most important meal of the day
Short answerSort of
On this page
Sort of. Trials don’t show that eating breakfast helps you lose weight, and people who skip it do fine. What they do show is that a breakfast with real protein in it cuts hunger for the rest of the day. The usual American breakfast is the plate with the least protein on it.
What we’d do
If you eat breakfast, make it a real plate, with about 30 g of protein and some fruit. If you’re not hungry in the morning, skip it, and make your first meal the good one. Either way, don’t eat a bowl of cereal just because a rule says to. A low-protein breakfast is the one meal that’s easiest to fix.
If you remember three things
- Breakfast on its own didn’t help weight. In 13 trials pooled, breakfast eaters ate about 260 more calories a day.
- A protein breakfast cut hunger. A 35 g protein breakfast lowered hunger and the day’s calories over 12 weeks.
- Cereal and milk is a D. A big bowl of Greek yogurt with blueberries, a banana and almonds is an A.
Why people believe it
It’s one of the most repeated lines in nutrition, and it sounds like body science. You’ve fasted all night, so breakfast “breaks the fast” and starts your metabolism, and skipping it makes your body hold on to fat.
The trials tell a different story about the metabolism part. bodyfat.guide covers that in full. This page is about the part that holds up, which is what’s on the plate.
A simple way to picture it
Breakfast is like the first gas stop on a road trip. You don’t have to stop, and plenty of people drive straight through to lunch. But if you do pull over, it’s what you put in the tank that gets you through the morning, and a coffee and a doughnut won’t get you far.
What the trials found
Breakfast or a morning fast
33 lean adults, 6 weeks. Betts and colleagues, 2014
Resting metabolism stayed within 11 calories a day either way. Breakfast eaters moved more, and also ate about 539 more calories a day.
Lean adults only.
Thirteen trials pooled
Sievert and colleagues, BMJ, 2019
Breakfast eaters ate about 260 more calories a day and weighed about 1 lb (0.44 kg) more than skippers.
The authors rated most of the trials low quality.
A 35 g, 13 g or no protein breakfast
57 young adults who usually skipped breakfast, 12 weeks. Leidy and colleagues, 2015
The skippers gained about 3.5 lb of fat. The 35 g group gained none, ate less over the day and was the only group with less hunger than the skippers.
Compared head to head, the 35 g and 13 g groups didn’t differ.
A big breakfast or a big dinner
30 adults with overweight, 4 weeks each way. Ruddick-Collins and colleagues, 2022
The same weight loss either way. People were less hungry with the big breakfast.
Both diets cut calories.
Put together, eating breakfast because it’s breakfast doesn’t do much. A breakfast with protein, or a bigger share of the day’s food in the morning, helped with hunger in two separate trials. That’s a good reason to eat one if you’re hungry, and to make it count.
Why the usual breakfast misses
In a 2014 study of protein through the day, the researchers noted that breakfast “is typically carbohydrate rich and low in protein”. The 2025 to 2030 US guidelines list “ready-to-eat or packaged breakfast options” among the refined carbohydrates to cut back on. On the meal checker, the breakfasts people eat most show the same thing. Most of them miss Muscle and Hunger, the two meters protein feeds, and the sweet ones miss Glucose too.
| Breakfast | Protein | Grade |
|---|---|---|
| A doughnut | 4 g | F |
| A bagel with butter | 9 g | D |
| Corn flakes and milk | 11 g | D |
| Oatmeal and a banana | 7 g | C |
| Two eggs on buttered whole wheat toast | 18 g | C |
| Greek yogurt and blueberries | 18 g | C |
| Three eggs, buttered whole wheat toast and strawberries | 25 g | B |
| Greek yogurt, blueberries, a banana and almonds | 25 g | B+ |
| The same with half a container more yogurt | 34 g | A |
The fixes are small. The checker’s one change for corn flakes is oatmeal with berries, which makes it a C+. For the doughnut it’s Greek yogurt and berries, which makes it a C. Adding a cup of fruit and a third egg to eggs on toast takes it from a C to a B, and a cup of Greek yogurt beside that makes it an A. The B and B+ breakfasts in the table clear every meter but one, Muscle, since 25 g is still short of the 30 g a 170 lb person needs at a meal. Some of the biggest upsets in meals that grade the opposite of what you’d guess are breakfasts.
Who should eat breakfast anyway
If you take a diabetes medicine that can cause low blood sugar, follow your care team’s advice on meal timing. If you’re hungry in the morning, or you find yourself raiding the snack drawer at 11, a protein breakfast is the fix. And if you lift in the morning, breakfast is a good place for one of your day’s protein plates. Muscle: protein on every plate shows what 30 g looks like.
7 sources
- Betts et al., The causal role of breakfast in energy balance and health: a randomized controlled trial in lean adults, American Journal of Clinical Nutrition, 2014europepmc.org
- Sievert et al., Effect of breakfast on weight and energy intake: systematic review and meta-analysis of randomised controlled trials, BMJ, 2019europepmc.org
- Leidy et al., A high-protein breakfast prevents bodyfat gain, through reductions in daily intake and hunger, in breakfast skipping adolescents, Obesity, 2015europepmc.org
- Ruddick-Collins et al., Timing of daily calorie loading affects appetite and hunger responses without changes in energy metabolism in healthy subjects with obesity, Cell Metabolism, 2022europepmc.org
- Mamerow et al., Dietary protein distribution positively influences 24-h muscle protein synthesis in healthy adults, Journal of Nutrition, 2014europepmc.org
- US Department of Agriculture and US Department of Health and Human Services, Dietary Guidelines for Americans, 2025 to 2030, January 2026cdn.realfood.gov
- Gebhardt and Thomas, Nutritive Value of Foods, USDA Agricultural Research Service, Home and Garden Bulletin 72, 2002 (the meal checker's food values)ars.usda.gov
