In People With Diabetes, Could Breakfast Really Be The Most Important Meal Of The Day?

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Nora Torres Yordan, Harvard Medical Student

“Breakfast is the most important meal of the day.” We’ve all heard (and likely repeated) this age-old phrase. Despite saying it, however, some of us might not live by it. Maybe we’re running late in the morning, or we think skipping it benefits our waistlines. Or perhaps some of us think this is one of those baseless statements well-meaning people make. 

Regardless of the reason, some of us are habitual breakfast skippers. It turns out, it’s not doing us any favors, especially for those of us who live with diabetes. 

Not having breakfast has been associated with obesity, high cholesterol, and yes, type II diabetes. In a large study that followed 29,206 men for 16 years, those who were breakfast-skippers were about 21% more likely to develop diabetes than those who reported eating breakfast, and this is after accounting for age, BMI, diet and various well-known risk factors for developing diabetes. It may not be just breakfast. Those who reported eating just 1-2 times per day still had an increased risk of diabetes when compared to those who reported eating three times per day. Other studies have shown similar findings in women.
 
So, if skipping breakfast increases the risk of developing diabetes, can eating breakfast help decrease one’s risk? Better yet, can we harness the power of breakfast (or brunch) to help improve blood sugar control in people with type II diabetes? Possibly!
 
A small, randomized cross-over study of 18 individuals with type II diabetes who were being treated with either Metformin (an oral drug) or dietary changes revealed that having a high-calorie breakfast and a low-calorie dinner improved their blood sugars after meals. This study randomly assigned people to adopt a diet with more calories at breakfast than dinner or vice versa for six days, and then on the 7th day, they came in to be evaluated. On the evaluation day, participants’ large meal consisted of 704 calories, lunch had 603 calories and their smaller meal had just 205 calories. On these evaluation days, investigators looked at blood sugar, insulin levels and other hormone levels for 3 hours after each meal to see what the levels looked like after adopting this diet. The participants could then go home and resume their normal diets. After two weeks passed, each participant crossed-over to the other arm (if on the high-calorie breakfast diet the first time around, they switched to the high-calorie dinner diet for 6 days and came in on day 7 for evaluation). This way, there was data for each person for both types of diet, which helped the study account for some of each person’s variability.
 
This study revealed that peak post-meal blood sugar levels were lower after each meal (breakfast, lunch and dinner) in the high-calorie breakfast group when compared to the high-calorie dinner group. Post-meal insulin, the hormone responsible for getting glucose from the blood into cells, also reached a higher level and it did so more quickly (within 60 vs. 120 minutes) in the high-calorie breakfast group. These beneficial differences in glucose spikes and insulin secretion were also seen after lunch, despite participants eating exactly the same meal for lunch on both test days. This suggests that eating a high-energy breakfast had a positive impact on participants’ hormone responses to food throughout the day.
 
Though this study had a small sample size and relatively short follow-up period, its results are quite promising. In the setting of our new understanding about circadian rhythms (our bodies’ internal clocks) and their important role in our responses to food, these data are particularly exciting. Despite being a relatively short-term study, following the glucose and insulin trends of participants throughout just one day, its results are consistent with those of another small, randomized trial which found that eating a large breakfast rich in protein and fats was associated with improvements in hemoglobinA1c (a marker of blood sugar levels over the past 2-3 months) and reductions in the dosing of medications for type II diabetes.
 
We still don’t know if these findings will hold up under further scrutiny. Neither of these small randomized trials had the same types of foods at each meal, which could mean that the composition of the meal rather than when they were eaten made the biggest difference. However, when taken together with the results of the large cohort study mentioned above, these results suggest that both eating breakfast and the foods we consume at breakfast (and at our other meals) have the potential to independently and significantly improve diabetes control.

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Author bio: Nora Torres is a fourth year student at Harvard Medical School hoping to pursue a career in Obstetrics and Gynecology. She graduated with a degree in Human Developmental and Regenerative Biology from Harvard College prior to transitioning to medical school. Her interest in nutrition and diabetes is grounded in the high prevalence of diabetes in her home town of Ponce, Puerto Rico and unequal prevalence of diabetes in low-SES and Latinx immigrant populations in the United States. In her spare time, Nora loves cooking with new fruits and vegetables and attending Zumba and barre classes at her local gym.