In this article, I looked into the research of eating vs not eating breakfast. This is an assessment of some of the largest studies on each topic however, by no means is this complete analysis of al studies out there as that would probably take weeks. If you don't care about the science and my speculative bits, just head straight to the final summery to get the key outcomes.
COGNITIVE PERFORMANCE A large analysis of 43 studies assessing the impact of eating breakfast on cognitive performance in children (4-18 years) looked at attention, memory, executive function, psychomotor function and language. What they found was that for attention, memory and executive functions having breakfast seemed to present an advantage, especially if the breakfast was made of a decent amount of protein (e.g. some eggs, beans, tofu, fish etc.) and had carbohydrates with low GL (glycaemic load) such as oats, millet, brown rice, legumes, wholegrain bread rather than breakfast made mostly of high GL carbohydrates such as toast, jam, sweet juice etc.
Similar findings came from other studies; however, an interesting observation is that while breakfast seems to affect the acute stages of cognitive performance: attention, executive skills, quick recall, it does not affect the long term performance such as long term memory.
At the same time, in some studies, actually not serving breakfast showed more benefits for overall cognitive performance. Overall, we cannot claim that breakfast definitely improves or does not improve cognitive performance, but the majority of studies suggest that there is probably a positive effect.
A possible explanation for this discrepancy is the following: If you have been reading my previous blog, you would have heard of BDNF, a promoter of neuroplasticity that is crucial for cognitive adaptation. This may be the missing piece of the puzzle that answers why in some cases skipping breakfast (especially skipping it for a long time) may be beneficial for attention or memory. At the same time, eating more carbohydrates means more glucose in the brain to be used for neurons. The brain has different requirements for glucose, depending on how “hard” it has to perform. A mentally demanding task such as exams in the university will burn significantly more glucose by the neurons of the brain than something like cleaning the dishes, which is literally an autopilot activity so what happens after breakfast is also important.
Also, the effects of serving breakfast are more profound in people who are undernourished and generally not as healthy compared to very healthy individuals with good metabolic adaptability. Being undernourished generally means less available vitamins and minerals for the brain and poorer brain performance, which is why we often see a rapid mental decline and a higher rate of dementia in people with severe prolonged eating disorders such as anorexia. Finally, it is worth mentioning that most of these studies on breakfast and cognitive performance are conducted on children and adolescents, not on adults, we know that as humans age, our metabolic flexibility gets poorer, and many processes, including energy production, slow down so this could be a potential factor here as well. As one of the studies put it: “Children and adolescents have a higher metabolic rate of glucose utilization, a higher average cerebral (brain) blood flow and oxygen utilization, than do adults. Their higher sleep demand implies longer overnight fasting, which can deplete glycogen stores overnight.”
MOOD & MENTAL HEALTH
A huge study that pooled data from 399,550 individuals has assessed the relationship between breakfast consumption and different factors of mental health. What they found was:
39% increased risk o depression for breakfast skippers
31% increased risk of anxiety for breakfast skippers
overall increased levels of self-perceived stress in breakfast skippers
In another study, testing 74 children (11-14), they found that having proper breakfast mostly dominant in carbohydrates with low glycaemic load (GL) and a good amount of protein, children overall had better performance on cognitive testing and felt more confident and self-assured when taking these tests.
CARDIOMETABOLIC HEALTH & BODY COMPOSITION
Many studies have been conducted to investigate whether skipping breakfast contributes to increased risk of heart disease. A fairly recent large systemic study that pooled in data from 284,000 participants across multiple trials has found that skipping breakfast raises the overall risk of developing heart disease by around 24%. Additionally, Breakfast skippers have been found to have a higher overall increase of LDL (the bad) cholesterol which is a key marker of cardiovascular risk so we may say that this is a pretty significant finding. Similar findings were also shown in other larger studies, along with increased triglycerides (more fat in the blood can indicate poor blood sugar control) for those who skipped breakfast.
Type 2 Diabetes
Skipping breakfast has also been significantly associated with developing Type 2 Diabetes later in life, which is a huge risk factor for cardiovascular disease. It appears that even when the scientists controlled for BMI (this means they were considerate of people’s body composition when creating the analysis), the risk was still significant for breakfast skippers. The increased risk of diabetes was seen even in that only skipping breakfast once or twice a week. The researchers concluded: “Studies have reported that the consumption of breakfast is not only associated with increased satiation and appetite regulation, but also with a higher dietary quality in general including higher intake of fibre, vitamins, and minerals and a lower intake of added sugars (54), which might have an influence on the risk of type 2 diabetes.” (Ballon et al. 2018).
In terms of body composition, the data has been and still is very inconsistent. Some studies show people who skip breakfast gain weight whole other show that they lose weight. Even the largest trials are showing conflicting results.
There are probably few reasons for this:
It could be because skipping breakfast means eating fewer calories throughout the day; however, there is the counter-argument that skipping breakfast causes more hunger later in the day, which will drive people to eat more in the evening when metabolism is the slowest, and the most weight is gained
There is also an element of what exactly is eaten. Breakfast made of sugary cereals with milk or of bacon and eggs will have a completely different metabolic response when compared to, say, whole grain bread with hummus, seeds, green vegetables and boiled egg. The composition of breakfast is usually not clear in these studies.
The final explanation is that people consuming breakfast regularly may be more health-conscious overall, and paying more attention to what they eat throughout the whole day while staying more active. At the same time, there are people who deliberately skip breakfast performing intermittent fasting and also eating very well; however, statistically speaking, this is a relatively modern thing (e.g. keto, IF etc), and most of these people are not part of these study populations as they would probably be excluded.
SUMMARY & RECOMMENDATION
Eating breakfast is associated with a variety of positive health benefits for cardiovascular health & diabetes prevention, healthy body composition, obesity prevention, mental health, better energy levels and overall nutrition balance (sufficient consumption of all vitamins and minerals). There are few important points here:
Breakfast should be made of a combination of more complex carbohydrates (oats, quinoa, wholegrain product, legumes) with good quality fats (nuts, seeds, avocado, ) and some good quality proteins (legumes, eggs, tofu, tempeh, nut butters, grains, fish)
Having breakfast that contains a lot of simple sugars (breakfast cereals, cornflakes, high sugar granola, toasts, jams, Nutella etc.) worsens our metabolic response and may negatively impact long term health and our cognitive performance
Breakfast should also contain a decent amount of fibre from natural plant foods such as fruit or vegetables to support optimal digestion and mood
For those skipping breakfast or performing intermittent fasting, it is essential to accommodate the lost calories into later meals and to ensure that they consume an adequate amount of protein and carbohydrates to support brain health and overall energy production
From my own personal experience, adding complex, high calorie breakfast made of good carbs, good fats and fruits to meals of my clients has nearly always resulted in more energy, better sleep, sharper mind, better exercise stamina and a more stable mood throughout the day.
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