Breakfast is the most important meal of the day — or is it? While it may have been something your mom told you as she tried to give you a bag of cereal as you walked out the door to school, it’s become a trend to intentionally skip a morning meal for health promotion in some cases, such as with intermittent fasting.

But what’s the real story? And how do registered dietitians advise their clients — especially those who say they just aren’t hungry in the morning? Here’s the scoop.

The Claim About Eating Breakfast

The origin of the original claim — that breakfast is the most important meal of the day — is based on a marketing campaign by a cereal manufacturer in the 1940s, as The Atlantic reported in 2016. The goal? To sell you more Grape Nuts, not to improve public health.

Since then, however, there has been a lot of research on how eating breakfast affects health and weight, as well as learning and cognitive performance in adults and children, says Ginger Hultin, RDN, owner of ChampagneNutrition in Seattle and author of Anti-Inflammatory Diet Meal Prep and How to Eat to Beat Disease Cookbook.

So while the origin of this claim wasn’t rooted in scientific evidence, there is now research to support the recommendation.

The Scientific Research on Whether to Eat Breakfast

While you can find studies supporting both sides of the debate, it’s important to focus on meta-analyses, which look at many studies on the same subject to find a conclusion, says Hultin. “The evidence seems to be most conclusive that skipping breakfast creates worse health outcomes for many people,” says Hultin.

For example, in a meta-analysis of 45 observational studies published in the January–February 2020 issue of Obesity Research & Clinical Practice, researchers concluded that skipping breakfast is associated with being overweight or having obesity. One reason? Skipping breakfast, or not eating for extended periods of time, may increase overeating at other times of the day, says Hultin. “This is extremely common and actually a pattern that’s tied to worse outcomes for weight management, not better,” she explains.

The choice to eat breakfast doesn’t only affect weight — metabolic health is also involved. A systematic review and meta-analysis published in November 2015 in Public Health Nutrition concluded that skipping breakfast correlated to a 21 percent increased risk of type 2 diabetes, and that eating breakfast could be protective against developing the disease.

And then there’s mental health. “There’s research that ties breakfast skipping to a higher odds of being depressed and stressed,” says Samantha Cassetty, RD, nutrition and wellness expert based in New York City and coauthor of Sugar Shock. She points to a systematic review and meta-analysis published in Nutritional Neuroscience in December 2020 that involved nearly 400,000 people. The data linked skipping breakfast a 55 percent higher likelihood of having psychological distress compared with people who ate breakfast.

That said, studies are conflicting. Take a meta-analysis published in January 2019 in BMJ, which looked at 13 randomized controlled trials. Participants who were instructed to eat breakfast consumed about 260 more calories compared with those who were in a breakfast-skipping group. (That said, as the authors point out, the quality of these studies were low — for one, they were conducted over an average of seven weeks — so more studies are needed.) Another meta-analysis, published in Obesity in June 2020, also looked at randomized controlled trials, finding that breakfast skipping was associated with about a pound of weight loss over two months compared with eating the meal, but skipping is also associated with an increase in “bad” LDL cholesterol. Longer-term studies are certainly warranted.

You could say that skipping breakfast is really the modern-day intermittent fasting. A popular eating pattern is called 16:8, in which people fast for 16 hours and eat for 8 hours per day. Often, they will start eating at noon. This type of eating may offer health benefits, including improving metabolic health for those who have obesity or diabetes, decreasing risk of cardiovascular disease and cancer, notes a review published in December 2019 in The New England Journal of Medicine. The authors hypothesize that this may be because fasting may switch the body into a ketogenic state, encouraging it to burn fat for fuel, and improving blood sugar levels, blood pressure, and decreasing visceral fat. But more studies are needed, and what’s clear is intermittent fasting isn’t for everyone. What’s more, health experts warn the eating plan may be unsustainable and may set some people up for overeating later in the day.

Nutritionally speaking, skipping breakfast may not be wise, Cassetty points out. “One study, published in Proceedings of the Nutrition Society in April 2021, noted that breakfast skippers consume fewer nutrients, like calcium, vitamin D, folate, and iron. Even when snacking more, breakfast skippers don’t make up the nutrients from the missed meal,” she says. As it is, many people don’t have balanced enough diets According to the U.S. Department of Agriculture (USDA), when it comes to eating a wide variety of healthful foods, Americans received an average score of 59 out of 100 on the “Healthy Eating Index,” which assesses diet quality. If you choose to skip your morning meal, you’ll really need to make sure that lunch, dinner, and snacks are on point.

It's also important to put this question into context. “There are many other factors that play a role in one’s risk of developing certain chronic conditions, aside from whether or not a person eats or does not eat breakfast, so it’s difficult to find conclusive evidence of one specific habit without looking at the bigger picture,” says Elizabeth Adrian, RD, founder of City to Sea Nutrition, an in-person and virtual nutrition counseling in New York City. Still, she recommends her clients eat breakfast to regulate hunger, prevent overeating, and get in a quality meal at the beginning of the day.

The Final Word on Whether You Need to Eat Breakfast

All three registered dietitians we interviewed recommend breakfast to their clients. But what you eat matters more than the specific timing. It’s okay to wait until you’re hungry, even if that comes later in the morning. Focus on whole, plant-based, fiber-filled foods and limit added sugars, refined grains, and excess sodium, says Cassetty. Scrambled eggs with veggies and whole-grain toast or a smoothie made with fruit, veggies (like spinach), nut butter, almond milk, and protein powder or Greek yogurt are two examples of power breakfasts that fit the bill.