Is breakfast really compulsory?

Where "the most important meal of the day" comes from

The phrase is so widespread that it is taken for a scientific fact. Its history is more modest. According to an article inJAMA, the dietitian Lenna Frances Cooper wrote in 1917 in the journal Good Health, published by the Battle Creek sanatorium (Michigan) run by John Harvey Kellogg, that breakfast is in many respects the most important meal, because it sets the day going.

Historians and nutrition researchers consider that the phrase owes much of its popularity to 20th-century cereal marketing. We were unable to consult a primary source on the specific manufacturer campaigns: the key point is that the slogan is old, has been repeated a great deal, and that its repetition is not proof.

Skipping breakfast and weight: what the trials show

The most studied question is weight. The meta-analysis bySievert et al., published in the BMJ in 2019, pooled 13 randomised controlled trials conducted in adults from high-income countries. Its results:

• in trials measuring weight (7 of 13), people who skipped breakfast lost slightly more weight, on average0.44 kgmore (confidence interval 0.07 to 0.82 kg);
• in trials measuring energy intake (10 of 13), those who had breakfast ate on average about260 kcal more per dayoverall.

The authors conclude that adding breakfast is not necessarily a good weight-loss strategy. They also flag important limitations: all trials had a high or unclear risk of bias on at least one criterion, durations were short (about seven weeks for weight, two for energy intake) and results varied widely from one trial to another. This work therefore does not say that skipping breakfast causes lasting weight loss, nor that it causes weight gain: it shows that any effect, if it exists, is small and poorly established.

Observational studies, which compare people who do or do not have breakfast, are more numerous, but they cannot demonstrate a cause-and-effect link: lifestyle, sleep or activity level often differ between the groups.

Concentration and performance: a matter of age and context

For children and adolescents, the systematic review byAdolphus et al. (2016)analysed 45 studies. It concludes that, compared with fasting, breakfast has a short-term benefit, on the same morning, for certain functions: attention, executive functions and memory. The benefits appear more clearly in undernourished children.

The authors specify that no firm conclusion can be drawn either on the ideal composition of breakfast or on the long-term effects of school programmes. They also note little data on adolescents, small samples and tests that are sometimes insensitive. Finally, the review was funded by Kellogg's USA, and several included studies were industry-funded, which the authors acknowledge as a risk of bias. For adults, data are scarcer and caution is needed.

Intermittent fasting: limited evidence

Intermittent fasting (eating only during certain time windows or on certain days) often leads to skipping breakfast. Areview of meta-analyses published in JAMA Network Open in 2021suggests that certain forms, notably modified alternate-day fasting, may help overweight or obese adults lose weight, with favourable effects on cardiometabolic markers. Its authors call for longer trials to verify effects on cardiovascular events and mortality.

In other words: the data mainly cover a few months and overweight adults, and they do not allow it to be made a rule for everyone. Intermittent fasting is one way of organising meals among others, not a cure, and we give no personalised advice.

Children, adolescents and specific situations

For younger people, the context is not the same as for adults. According to a document fromEduscolciting the INCA 3 study by ANSES, breakfast is the least regularly eaten of the three meals, and on average 3.4 pupils per class arrive at school having eaten nothing, rising to 13% in priority education areas (we only read an extract of this document). For children and adolescents, the official dietary guidelines are detailed in our article onchild nutrition.

People with diabetes, those on treatment (particularly for diabetes) or those under special medical supervision should not change their meals based on an article: this is a question to ask their doctor or dietitian. Our article ondiabetes and the glycaemic indexgives general guidance, without replacing that advice.

What a balanced breakfast looks like

When one is eaten, the usual pattern in France is built on four elements, as presented for example byVidal(we could not consult the official Manger Bouger page, offline at the time of research):

• adrink: water, tea, coffee or milk;
• acereal product: bread, rusks, oat flakes or muesli, preferably over sweetened cereals;
• adairy product: milk, yogurt, fromage blanc, for calcium and protein;
• afruit, preferably whole. Juice is possible but contains less fibre and counts as a sugary drink.

A little butter, honey or jam completes the meal. The same page stresses a useful point: quantities are set by hunger and satiety, and what matters is to eat the equivalent of a breakfast during the morning, not at a fixed time. For other meals, seebalanced meals: lunch, dinner and snacks.

Common industrial breakfast products

Sweetened cereals, breakfast biscuits, brioches and fruit juices are practical but often high in sugars. We were unable to read an OQALI report quantifying current levels by product family: to compare, look at the "of which sugars" line in the nutrition table, per 100 g, as explained in our article onhidden sugar and salt. ANSES also recommendsnot exceeding 100 g of sugars per day (excluding lactose and galactose) and no more than one glass of sugary drink, juice included in the reasoning; see our comparisonfruit juice vs soda.

Many of these products are also classed asultra-processed. A few simple alternatives, without claiming perfection:

• Someoat flakesor a muesli without added sugars, with milk or plain yogurt;
• Somebread(wholemeal if you like it) with a little butter, jam or fresh cheese;
• awhole fruitrather than a juice;
• aplain yogurtor fromage blanc, sweetened to taste.

To judge a specific product, readthe label: the ingredients list, ordered by decreasing weight, quickly tells you whether sugar comes first. In Yumiq, the product page shows the number of additives detected (harmless, to watch, risky). The Yumiq-Score penalises controversial additives assessed by the EFSA and ANSES, and the Yumiq star requires the absence of risky additives.

What to take away

• The "most important meal" slogan is old and widely repeated, but it is not backed by solid evidence for everyone.
• Trials on weight are short and of limited quality: the effect of having or skipping breakfast is small and uncertain.
• In children, breakfast has a short-term effect on attention and memory in studies, especially if the child is undernourished.
• Listening to your hunger matters more than dogma: a simple, quality breakfast is better than sugary products out of habit, and skipping breakfast is not a fault in itself.
• For diabetes, treatment or doubt, it is for the doctor to decide.

Sources

• BMJ 2019, Sievert et al.: effect of breakfast on weight and energy intake (PubMed)
• Advances in Nutrition 2016, Adolphus et al.: breakfast and cognitive performance in children and adolescents
• JAMA Network Open 2021, Patikorn et al.: intermittent fasting, review of meta-analyses (PubMed)
• JAMA 2019, Rubin: skipping breakfast and weight
• ANSES - Sugars in the diet
• Eduscol - School breakfasts (INCA 3 data)
• Vidal - Building a balanced breakfast