Introduction
How can we define important?
What does the research say?
The effect of breakfast on resting metabolic rate
Breakfast and its impacts on human health
References
Further reading
Breakfast is often referred to as the most important meal of the day. In recent years it has been implicated in the control of weight, considered a cardiometabolic risk factor, and implicated in cognitive performance. Moreover, the prevailing opinion is that breakfast is an important factor in helping consumers attain an optimal nutrition profile – although this does not consider the macro and micronutrient content of the foods consumed.
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Despite these claims, the literature is inconclusive regarding the precise health benefits of eating breakfast. Several studies have been conducted that compare daily food and nutrient intakes in breakfast consumers versus those who skip breakfast; despite this, significant variation exists in the methodology used to compare the two groups as well as the methods used to analyze nutrient intakes and overall diet quality.
How can we define important?
The term important is subjective and depends on an individual's lifestyle. For example, those who engage in physical exercise in the morning are unlikely to prioritize breakfast relative to other meals in the day and are likely to consume a carbohydrate-rich choice of foods. If importance is related to long-term health outcomes, importance is judged relative to a consistent pattern i.e., over long-term habits.
What does the research say?
Intervention studies attempting to quantify the response to chronic breakfast consumption or admission do not provide clear evidence in comparison to laboratory investigation. Two recent studies using crossover designs of one-week duration reported no difference in energy intake when participants either fasted or consumed a high carbohydrate breakfast in laboratory conditions.
In another study, no dietary limitations were imposed on participants in the group consuming breakfast. In lean individuals, the group found that limited dietary compensation occurred in the breakfast group; they consumed 539 calories more compared to those in the lean fasting group. In the obese cohort, however, the energy intake was not statistically significantly different between the breakfast and fasting groups. Those who were assigned breakfast consumed 338 calories per day more than their obese counterparts in the non-fasting group.
The findings from earlier studies suggest that obese individuals tend to compensate more for a morning energy deficit than lean individuals in non-laboratories conditions. The discord between the two groups of people suggests that lean and obese people are differentially affected by environmental factors; for example, the energy intake compensation found in the obese cohort could be a result of food choices and frequency of eating.
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The effect of breakfast on resting metabolic rate
Resting metabolic rate is considered to be the largest contributor to total energy expenditure. Resting metabolic rate tends to decrease in cases of starvation and lower body mass. Previous studies have measured change in resting metabolic rate in response to a sustained morning feeding intervention. Weight loss induced by caloric restriction in obese women caused similar reductions in resting metabolic rate, but crossover intervention found no difference in resting metabolic rate following breakfast consumption or skipping. These effects have been mirrored in a similar study which demonstrated that no difference in resting metabolic rate or body weight was found in those who skipped or consumed breakfast.
Therefore, evidence universally shows that consistently extending the overnight fast by skipping breakfast does not directly affect resting metabolic rate, outside of the effect observed when weight loss results from energy intake decreasing over a long period.
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Breakfast and its impacts on human health
There is a substantial body of research that suggests that those who omit breakfast are at an increased risk of disease. Randomized controlled trials have demonstrated causal mechanisms that explain these observations. One study has reported increased lipoproteins relative to a -meal pattern when individuals adhered to a one-meal-a-day regimen. Similarly, a study demonstrated that delaying food intake until later in the morning for two weeks caused total and LDL cholesterol and insulin response to a test drink to increase relative to a decrease observed when consuming breakfast daily.
The information from prospective studies examining risk factors for cardiovascular disease demonstrates consistent and strong cross-sectional evidence to demonstrate that breakfast consumption is associated with a reduction of cardiometabolic risk factors.
Conversely, a pilot study published in 2018 has demonstrated that intermittent fasting can improve blood glucose and incident sensitivity and lower blood pressure. It is important to note that studies of a larger size, as well as the long-term benefits, remain to be assessed.
The negative health consequences of skipping breakfast
- Circadian rhythm abnormalities
- An increased risk of heart disease (27%)
- High risk of type 2 diabetes in both men and women (21% and 20% respectively)
- Increased risk of obesity (although the association between eating breakfast and obesity is thought to be as a result of improved knowledge about nutrition and health among those who consume breakfast rather than an alteration in total energy intake, and associated with a higher probability of adopting positive additional lifestyle factors, like not smoking and regular exercise)
Moreover, a meta-analysis of available studies has demonstrated that breakfast intake is associated with improved cognitive function, particularly noticeable short-term benefits on attention, memory, and executive function. However, researchers noted that there are insufficient studies for any firm conclusions to be drawn.
Overall evidence suggests that omitting breakfast affects some components of energy balance. There is no evidence to suggest that breakfast consumption affects resting metabolic rate or diet-induced thermogenesis produced from consuming subsequent meals over a day. Evidence emission does affect energy intake for the day, with several studies showing energetic compensation in subsequent meals. In many cases, it is not sufficient to eliminate the deficit caused by morning fasting; this contrasts with the prevailing view that energetic compensation is caused by skipping breakfast. This deficit is smaller in obese individuals, but a deficit still occurs across the board. Therefore, it may be regarded as a lifestyle choice, with no notable health risks associated with consuming or skipping the meal.
Ultimately, the choice to consume breakfast is individual, there are both positives on negatives associated with either eating or skipping the meal, and may be more important for those who are hungry when they first awake. There is no conclusive evidence to suggest whether breakfast is the most important meal of the day and, therefore important to consider personal circumstances and preferences. For example, those who are pre-diabetic and diabetic may find consuming a lower GI breakfast beneficial and help them concentrate better.
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References
- Betts JA, Chowdhury EA, Gonzalez JT. (2016) Is breakfast the most important meal of the day? PNS. doi: 10.1017/S0029665116000318.
- Ruddick-Collins LC, Johnston JD, Morgan PJ, et al. (2018) The Big Breakfast Study: Chrono-nutrition influence on energy expenditure and body weight. Nutr Bull. doi:10.1111/nbu.12323.
- Jakubowicz D, Wainstein J, Landau Z, et al. (2017) Influences of Breakfast on Clock Gene Expression and Postprandial Glycemia in Healthy Individuals and Individuals With Diabetes: A Randomized Clinical Trial. Diabetes Care. doi: 10.2337/dc16-2753.
- Sutton EF, Beyl R, Early KS, et al. (2018) Early Time-Restricted Feeding Improves Insulin Sensitivity, Blood Pressure, and Oxidative Stress Even without Weight Loss in Men with Prediabetes. Cell Metab. doi: 10.1016/j.cmet.2018.04.010.
- Leidy HJ, Gwin JA, Roenfeldt CA, et al. (2016) Evaluating the Intervention-Based Evidence Surrounding the Causal Role of Breakfast on Markers of Weight Management, with Specific Focus on Breakfast Composition and Size. Adv Nutr. doi:10.3945/an.115.010223.
Further Reading