Every year on 18 March, the phrase “National Breakfast Day” pops up across media channels, a marketing-friendly celebration of the meal many of us were told we should never skip.

It’s the meal that supposedly kick-starts metabolism, fuels the brain, and sets the tone for the day.

And of course, it’s the meal we’ve all heard described as: “The most important meal of the day.”

But here’s something most people don’t realise. That famous phrase may have less to do with nutrition science…and more to do with one of the most successful food marketing campaigns in history.

To understand how breakfast earned its legendary status, we need to travel back more than a century, to the birth of the modern breakfast cereal industry.

How Breakfast Became “Essential”

In the late 1800s, American physician Dr. John Harvey Kellogg began promoting a particular vision of health and diet. Kellogg believed that simple, grain-based foods were ideal for digestion and overall well-being. Working at the Battle Creek Sanitarium in Michigan, he and his brother later developed one of the world’s first ready-to-eat breakfast cereals: cornflakes.

What began as a “health” food quickly became a commercial success.

As cereal production expanded in the early 20th century, manufacturers promoted the idea that a grain-based breakfast was the ideal way to begin the day. Advertising campaigns and health messaging increasingly reinforced a simple but powerful idea: Skipping breakfast was unhealthy.

Over time, the slogan “breakfast is the most important meal of the day” became deeply embedded in culture, public health messaging, and everyday advice.

History shows that this pattern repeats itself in nutrition science. Ideas can become widely accepted long before they are rigorously tested, shaped not only by emerging evidence but also by cultural trends, public health messaging, and commercial interests. When researchers eventually begin asking careful questions, the “truths” we thought were settled often turn out to be more complex than they first appeared.

What Does the Science Actually Say?

Modern nutrition research has increasingly questioned whether breakfast itself has a unique metabolic advantage. A scientific review concluded that there is currently no clear metabolic benefit to eating breakfast compared with skipping it, when outcomes such as body weight, energy expenditure, and metabolic health are examined in controlled studies (Betts et al., 2016). Similarly, a systematic review and meta-analysis of randomized controlled trials found that adding breakfast to the diet did not promote weight loss and may increase total daily energy intake in some individuals (Sievert et al., 2019).

Observational studies sometimes show associations between breakfast skipping and poorer health outcomes. However, researchers caution that these findings are often influenced by broader lifestyle factors such as diet quality, sleep patterns, physical activity, and socioeconomic status (Ricotti et al., 2021).

In other words, breakfast itself may not be the deciding factor; overall dietary patterns appear to matter far more.

The Rise of Intermittent Fasting

One reason breakfast has become a topic of renewed scientific interest is the growing popularity of intermittent fasting and time-restricted eating.

These approaches focus less on the number of meals consumed and more on the timing of eating across the day. Clinical trials suggest that time-restricted eating may support improvements in body weight, insulin sensitivity, blood pressure, and other cardiometabolic markers, although outcomes vary between individuals and study designs (Jamshed et al., 2022).

From a physiological perspective, periods without food allow the body to shift from relying on circulating glucose to drawing on stored energy. This metabolic flexibility may play an important role in maintaining healthy glucose regulation.

What You Eat Matters More Than When

While the timing of meals receives a great deal of attention, another factor may be even more important: What breakfast actually contains. Many “traditional” breakfast foods, particularly cereals, pastries, and sweetened drinks, contain large amounts of refined carbohydrates and sugars. These foods can produce rapid spikes in blood glucose followed by mid-morning energy crashes.

In contrast, whole foods such as eggs contain high-quality protein and fats that tend to produce greater satiety and more stable metabolic responses. Clinical studies comparing egg-based breakfasts with cereal-based breakfasts have shown that participants who eat eggs often report greater fullness and reduced calorie intake later in the day (Ratliff, 2010; Keogh et al., 2020).

This suggests the metabolic effects of breakfast may depend less on the clock and more on the nutritional composition of the meal itself.

So, Is Breakfast Really the Most Important Meal?

The scientific answer is more nuanced than the slogan suggests. For some people, eating breakfast may improve concentration, appetite control, or daily nutrient intake. For others, delaying the first meal of the day, allowing for a longer overnight fasting period, may fit better with their metabolism or lifestyle.

What modern research increasingly suggests is that the real question may not simply be whether we eat breakfast, but rather:

• What foods do we choose
• How those foods influence blood sugar and satiety
• How eating patterns support overall metabolic health

 

National Breakfast Day may be a fun celebration of morning meals. But it also reminds us that many of the nutrition messages we grew up with were shaped much more by history and marketing than they were by science.

New Research: Eggs, Fasting, and Metabolic Health

Building on this growing interest in meal timing and food quality, researchers at The Noakes Foundation are currently exploring how different foods influence metabolic responses following an overnight fast. The study is examining how foods such as eggs compare with other low-carbohydrate foods in their effects on blood glucose, satiety, and metabolic markers when consumed as the first meal of the day. By measuring changes in blood sugar, blood pressure, inflammation, body weight, and waist circumference over time, the research aims to better understand how simple dietary shifts may influence metabolic health in real-world settings. This work forms part of a broader effort to generate locally relevant nutrition evidence in a South African context, where rates of diabetes and metabolic disease continue to rise.

Individuals interested in learning more about the study or participating in future research are welcome to get in touch. For more information, please contact Karen Heath at The Noakes Foundation at: karen@thenoakesfoundation.org.

 

References

Betts JA, Chowdhury EA, Gonzalez JT, Richardson JD, Tsintzas K, Thompson D. Is breakfast the most important meal of the day? Proc Nutr Soc. 2016 Nov;75(4):464-474. doi: 10.1017/S0029665116000318. Epub 2016 Jun 13. PMID: 27292940.

Sievert K, Hussain SM, Page MJ, Wang Y, Hughes HJ, Malek M, Cicuttini FM. Effect of breakfast on weight and energy intake: systematic review and meta-analysis of randomised controlled trials. BMJ. 2019 Jan 30;364:l42. doi: 10.1136/bmj.l42. PMID: 30700403; PMCID: PMC6352874.

Ricotti R, Caputo M, Monzani A, Pigni S, Antoniotti V, Bellone S, Prodam F. Breakfast Skipping, Weight, Cardiometabolic Risk, and Nutrition Quality in Children and Adolescents: A Systematic Review of Randomized Controlled and Intervention Longitudinal Trials. Nutrients. 2021 Sep 23;13(10):3331. doi: 10.3390/nu13103331. PMID: 34684332; PMCID: PMC8539462.

Jamshed H, Steger FL, Bryan DR, Richman JS, Warriner AH, Hanick CJ, Martin CK, Salvy SJ, Peterson CM. Effectiveness of Early Time-Restricted Eating for Weight Loss, Fat Loss, and Cardiometabolic Health in Adults With Obesity: A Randomized Clinical Trial. JAMA Intern Med. 2022 Sep 1;182(9):953-962. doi: 10.1001/jamainternmed.2022.3050. PMID: 35939311; PMCID: PMC9361187.

Ratliff J, Leite JO, de Ogburn R, Puglisi MJ, VanHeest J, Fernandez ML. Consuming eggs for breakfast influences plasma glucose and ghrelin, while reducing energy intake during the next 24 hours in adult men. Nutr Res. 2010 Feb;30(2):96-103. doi: 10.1016/j.nutres.2010.01.002. PMID: 20226994.

B Keogh J, M Clifton P. Energy Intake and Satiety Responses of Eggs for Breakfast in Overweight and Obese Adults-A Crossover Study. Int J Environ Res Public Health. 2020 Aug 3;17(15):5583. doi: 10.3390/ijerph17155583. PMID: 32756313; PMCID: PMC7432073.