23rd April, 2019, Dr Chee L Khoo
Somehow, it has been drummed into us, as doctors and consumers, that breakfast is the most important meal of the day. What does that even mean? As discerning scientists, we should seek to clarify what outcome measures they are referring to when they say, “the most important meal of the day”. We should also question what type of breakfast they are referring to and the subjects recruited in the studies. Do the recommendations equally apply to patients with diabetes or normo-glycaemic subjects? Or were the recommendations extrapolated from recommendations for patients with type 1 diabetes (T1D) who needs certain amount of carbohydrates?
Most of these recommendations are based on observational studies. Bias and confounding issues were not well addressed. For example, subjects who do not eat breakfast may not eat breakfast because of socio-economic reasons and as such, may not generally have healthy eating habits anyway. Further, imposing additional breakfast calories to an established eating pattern in older patients may be counter-productive.
Type of breakfast
Have you seen the carbohydrate content in the breakfast most of our patients eat? It definitely isn’t the breakfast that we would consider “healthy”. Cereals, toasts, oatmeal, fruits and other high carbohydrate breakfast hardly qualify as “healthy” nor nutritional in my books. Nutrition guidelines internationally are generally broad in regard to the amount of carbohydrates that should be in the breakfast meal.
Dietary carbohydrate is the primary culprit in postprandial hyperglycaemia. Breakfast often results in the largest post prandial hyperglycaemic excursion of the day. Post-prandial hyperglycaemia is a major contributor to glycaemic variability which has been shown to be associated with cardiovascular complications of diabetes. Surely, carbohydrate can’t be good in your breakfast.
A recent study published in the American Journal of Clinical Nutrition, examine the impact of carbohydrate restriction at breakfast on postprandial hyperglycaemia in individuals with well-controlled type 2 diabetes (T2D) (1). 23 subjects completed two 24-hour trials in a randomised cross-over study. The breakfast in trial 1 was a low-carbohydrate breakfast (LCBF) consisting of <10% carbohydrate, ∼85% fat, and ∼15% protein and trial 2 was a guideline recommended breakfast (GLBF) consisting ∼55% carbohydrate (focusing on low glycaemic index), ∼30% fat, and ∼15% protein as recommended by the Canadian Diabetes Association Clinical Practice Guidelines. As much as possible, identical lunch and dinner were provided. Calories were matched between conditions for each meal and total 24-h period within participants. Continuous glucose monitoring was used to compare the post prandial glucose excursion between the two trial breakfast.
Results
The postprandial glucose response to breakfast was reduced by 74% when carbohydrates were restricted to <10% of breakfast caloric intake. LCBF lowered the glucose excursion at breakfast to an extent that overall exposure to postprandial hyperglycaemia and glycaemic variability were improved over a 24-h period. Glycaemic variability (frequency and magnitude of 24-h glucose oscillations) as assessed by mean amplitude of glucose excursion (MAGEs) was significantly reduced when an LCBF, rather than a GLBF, was consumed.
In addition, ratings of premeal hunger and desire to eat sweet foods later in the day tended to be lower in the LCBF condition. The encouraging preliminary findings showing lower hunger later in the day following an LCBF also indicates that this approach could have wider implications for weight loss, but this will require further research.
Dietitians generally recommend spreading out the carbs for the day. However, Pearce et al. (2) previously showed that an even distribution of carbohydrates across the day does not provide the most favourable 24-h glucose profile. This study further reinforce that finding.
Patient type
The optimal timing of carbohydrates may depend on the individual’s degree of glycaemic control. In healthy adults, responses to carbohydrates appears to be higher in the evening (3,4), which is likely related to the opposite diurnal variation in glucose tolerance and insulin sensitivity seen in healthy adults compared with individuals with T2D. Patients with diabetes may have a different response to carbohydrates at breakfast.
Outcome measures
The recommendations not to miss breakfast is derived from the presumption that missing breakfast may lead to snacking the rest of the day and overcompensation and this leads to weight gain. The US Academy of Nutrition and Dietitics commented for adults that “Skipping breakfast won’t help you lose weight. You could miss out on essential nutrients and you may end up snacking more throughout the day because you feel hungry.” (5)
It is also based on the presumption that eating earlier in the day promote greater satiety than eating later in the day. The Dieticians Association of Australia’s fact sheet suggests “… consuming breakfast regularly is associated with lower levels of overweight and obesity. Breakfast fills you up, meaning you are less likely to experience hunger pangs throughout day and resort to snacking on high energy, high fat foods.” (6)
It is also thought that missing breakfast may miss out on essential nutrients. For example, in the UK, they recommend: “Skipping breakfast won’t help you lose weight. You could miss out on essential nutrients and you may end up snacking more throughout the day because you feel hungry.” (7,8)
These recommendations are not based on level 1 evidence from randomised controlled trials but from observational trials. In fact, several randomised controlled trials do not generally support a beneficial effect of breakfast eating on weight loss. (9,10). They also assumed that the breakfast our patients have are actually “healthy”. Thus, “the most important meal of the day” have no proven nutrient or weight loss benefits at all.
In summary, missing breakfast does not necessary increase hunger for the rest of the day. Nor does missing breakfast cause weight gain. Missing breakfast doesn’t increase hyperglycaemic response later in the day. To the contrary, missing breakfast may assist in weight loss in some patients. If you can’t miss breakfast, at least keep the carbohydrate content of your breakfast to a minimum, especially if you have T2D.
References
- Courtney R Chang, Monique E Francois, and Jonathan P Little. Restricting carbohydrates at breakfast is sufficient to reduce 24-hour exposure to postprandial hyperglycemia and improve glycemic variability. Am J Clin Nutr 2019;0:1–8.
- Pearce KL, Noakes M, Keogh J, Clifton PM. Effect of carbohydrate distribution on postprandial glucose peaks with the use of continuous glucose monitoring in type 2 diabetes. Am J Clin Nutr 2008;87(3): 638–44.
- Carroll KF, Nestel PJ. Diurnal variation in glucose tolerance and in insulin secretion in man. Diabetes 1973;22(5):333–48.
- Saad A, Dalla Man C, Nandy DK, Levine JA, Bharucha AE, Rizza RA, Basu R, Carter RE, Cobelli C, Kudva YC. Diurnal pattern to insulin secretion and insulin action in healthy individuals. Diabetes 2012;61(11):2691–700.
- Academy of Nutrition and Dietetics. Adult weight management (AWM) guideline. 2014. https://www.andeal.org/vault/pq132.pdf
- Council NHaMR. Dietary guidelines for all Australians. 2013. https://daa.asn.au/resource/breakfast-cereals-and-body-weight-fact-sheet/
- British Dietetic Association. Healthy breakfast. 2016. https://www.bda.uk.com/foodfacts/healthy_breakfast
- Public Health England. The Eatwell Guide Booklet. 2016. https://assets.publishing.service.gov.uk/government/uploads/system/uploads/attachment_data/file/742750/Eatwell_Guide_booklet_2018v4.pdf
- Chowdhury EA, Richardson JD, Holman GD, Tsintzas K, Thompson D, Betts JA. The causal role of breakfast in energy balance and health: a randomized controlled trial in obese adults. Am J Clin Nutr 2016;103:747-56. doi:10.3945/ajcn.115.122044
- LeCheminant GM, LeCheminant JD, Tucker LA, Bailey BW. A randomized controlled trial to study the effects of breakfast on energy intake, physical activity, and body fat in women who are non-habitual breakfast eaters. Appetite 2017;112:44-51. doi:10.1016/j. appet.2016.12.041