Is breakfast the most important meal of the day?

Question

This question is not about nutrition. I am not asking whether the kinds of foods that people typically have during breakfast (esp. cereals) are healthier than other foods.

The claim is often made that the food is somehow digested “better” (more efficiently?) when consumed early in the day (shortly after waking up). It is claimed furthermore that extreme deviation from a traditional three-meal rhythm (esp. eating stuff in the middle of the night) is unhealthy. How much is there to it?

I am skeptical about these claims because I have seen no reason to believe that the digestive system is any less capable of digesting food at any time during the day. Although it may well be slower in digesting food at some times than others, I don’t see how that makes any difference to energy content and health consequences.

Answer 1

The three meal standard that people use is more a cultural than biological function. If you look at how humans foraged and ate before we settled into cities and started agriculture, we were "snackers". We would eat numerous small portions throughout the day instead of a couple of large meals. Our attempts to align our current societal habits with our evolutionary mechanisms don't always work.

Going longer periods without food is generally a precursor to attempting to gorge yourself since the survival centers of the brain may think that you are entering a food scarce time period.

Proceedings of the Nutrition Society: Cambridge Journals. This could probably be a good scientific paper that talks about how our eating habits are not quite in line with our evolution.

Human eating behaviour in an evolutionary ecological context Stanley J. Ulijaszek Institute of Social and Cultural Anthropology, University of Oxford, 51 Banbury Road, Oxford OX2 6PE, UK

Present-day human eating behaviour in industrialised society is characterised by the consumption of high-energy-density diets and often unstructured feeding patterns, largely uncoupled from seasonal cycles of food availability. Broadly similar patterns of feeding are found among advantaged groups in economically-emerging and developing nations. Such patterns of feeding are consistent with the evolutionary ecological understanding of feeding behaviour of hominids ancestral to humans, in that human feeding adaptations are likely to have arisen in the context of resource seasonality in which diet choice for energy-dense and palatable foods would have been selected by way of foraging strategies for the maximisation of energy intake. One hallmark trait of human feeding behaviour, complex control of food availability, emerged with Homo erectus (1·9 ´ 106-200 000 years ago), who carried out this process by either increased meat eating or by cooking, or both. Another key trait of human eating behaviour is the symbolic use of food, which emerged with modern Homo sapiens (100 000 years ago to the present) between 25 000 and 12 000 years ago. From this and subsequent social and economic transformations, including the origins of agriculture, humans have come to use food in increasingly elaborate symbolic ways, such that human eating has become increasingly structured socially and culturally in many different ways.

Answer 2

No, breakfast is not the most important meal of the day.

This article analyses a few studies looking at the effects of different meal patterns: Is Late Night Eating Better for Fat Loss and Health?

It suggests that skipping breakfast is beneficial for fat-loss, and other health indicators.

True, this guy wrote a book about this subject, so clearly, he must have an agenda. But he still found 5 controlled studies done on the subject.

Dietary epidemiology commonly find associations between certain meal patterns and higher BMI / body fatness. However, this association can solely be attributed to lifestyle-related factors and eating behaviors; snacking in front of the TV in the evening, making poor food choices in general, and so forth. People who eat more in the evening simply eat more calories, which explains why they weigh more.

Calorie-controlled studies looking at the effects of distributing a fixed caloric load differently throughout the day are scarce; I have listed all of them above. These tell a much different story than the one found in dietary epidemiology. While short-term studies (15-18 days) do not find a statistically significant difference between early and late meal patterns, long-term studies (>12 weeks) show that late eating patterns produce superior results on fat loss, body composition and/or diet adherence. This might be explained by more favorable nutrient partitioning after meals due to hormonal modulation.

I wonder if any other studies were conducted on the subject with contradicting results (that the author failed to find/list due to some sort of confirmation bias.)

Answer 3

According to this article: http://www.bbc.co.uk/news/health-19962588 , although the author does not state that eating exactly the same food at different times of the day makes a difference, it claims that skipping breakfast subconsciously influences the brain to seek out food with higher calories, resulting in subjects of normal weight eating 20% more calories after missing breakfast:

Twenty one people, who were all normal weight, were shown pictures of calorie packed foods while they were positioned in a magnetic resonance imaging (MRI) machine at Imperial College London.

On one day they were given no breakfast before the scans and on a different day they were fed a large, 730 calorie, breakfast an hour and a half before.

The researchers said skipping breakfast created a "bias" in the brain in favour of high calorie foods.

The results, presented at the Neuroscience 2012 conference, showed the brain changed how it responded to pictures of high calorie foods, but not low calorie foods, when breakfast was skipped.

They showed part of the brain thought to be involved in "food appeal", the orbitofrontal cortex, became more active on an empty stomach.

When the researchers offered the participants lunch at the end of the study, people ate a fifth more calories if breakfast was missed.

It implies, though not explicitly state, that the additional 20% is a total, i.e.

lunch_skip = 1.2 x (lunch_{no skip} + breakfast_{no skip})

instead of

lunch_skip = 1.2 x lunch_{no skip}