Researchers explore: Can skipping breakfast harm your health?

By Naveed Saleh, MD, MS, for MDLinx
Published March 5, 2020

Key Takeaways

Nearly one-quarter of Americans skip breakfast, which comprises about 16% of total caloric intake for the day, according to the authors of a letter to the editor in The American Journal of Clinical Nutrition. Because so many people skip breakfast, its effect on public health is a valid concern. 

Although data on the topic are often mixed, here’s a look at some important studies that explore the value of daily breakfast consumption and its effect on energy levels and weight loss.  

Thermogenesis and weight loss

Daily energy expenditure is comprised of three primary components: basal metabolic rate, diet-induced thermogenesis (DIT), and the energy cost of physical activity. DIT is essentially defined as energy dissipated as heat after a meal.

In one low-power (n = 16) in-laboratory, randomized, crossover study, researchers found that eating the most calories at breakfast vs at dinner resulted in a 2.5-fold higher increase in DIT. Furthermore, participants who ate higher-calorie breakfasts had lower increases in blood glucose and insulin levels. On the flip side, low-calorie breakfasts resulted in increased feelings of hunger and cravings for sweets during the day.

“Our results show that a nutritional pattern with an extensive breakfast and few calories in the evening has a favorable effect on energy as well as glucose metabolism,” wrote the authors.

“Overall, the diurnal variations in DIT, independent of the calorie content of the meals, imply that the time of food intake is important not only in the prevention of obesity but also in terms of diets for weight loss,” they added. “An extensive breakfast should therefore be preferred over large dinner meals to reduce the risk of metabolic diseases.”

Energy dynamics

According to the results of a review article published in Proceedings of the Nutrition Society, people who skip breakfast tend to eat more calories later in the day. However, although the extra calories consumed throughout the day do not exceed those skipped at breakfast, the early morning fast can decrease energy levels.

“Our work in both lean and obese individuals suggests that breakfast omission may lower physical activity energy expenditure, particularly during the morning, although this needs confirmation and the potential reasons for this phenomenon remain to be established,” wrote the authors.

“The majority of studies conducted to date have been of relatively short duration, but those that have examined the effect of breakfast omission upon body weight do not support the strongly established public perceptions and correlational evidence that omission of breakfast is associated with weight-gain,” they concluded.

Heart health

Breakfast could have a big impact on heart health because it is linked to various related factors, including satiety, appetite regulation, metabolic efficiency, and energy intake. A number of researchers have tied breakfast omission to diabetes and unfavorable lipid status. 

For instance, in a high-powered observational study, researchers found that skipping breakfast was related to a higher frequency of noncoronary and generalized atherosclerosis, compared with eating a high-energy breakfast (greater than 20% of calories consumed daily).

“Skipping breakfast could serve as a marker of unhealthy dietary and lifestyle behavior and is associated with the presence of noncoronary and generalized atherosclerosis independent of conventional [cardiovascular disease] risk factors in a sample of middle-aged asymptomatic individuals,” the authors concluded. “Our findings highlight the message of the importance of healthy eating, including an energetic breakfast.”

Eating breakfast is probably beneficial. Nevertheless, different people harbor different biologic rhythms, as well as different inclinations to break their overnight fasts earlier in the day. Notably, some evidence supports the prospect that people tend to get hungrier later in the day. Moreover, mechanisms responsible for the integral nature of breakfast remain lacking in the literature.

Ultimately, longer-term studies are needed to establish the effect of breakfast on a variety of biomarkers—especially in overweight and obese individuals. Until then, it’s unclear whether breakfast is truly the “most important” meal of the day.

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