By Matt Wang, MS Candidate in Human Nutrition
It’s lunchtime. You walk towards the staff refrigerator and take out your Tupperware with last night’s leftovers: salmon, salad, and rice. You’re ravenous, but remember that you have a presentation at 2 pm that you can’t risk being food coma-ed out for. What do you do? A. Eat your lunch and feel drowsy during the presentation, B. Eat half your lunch and risk unleashing your hangry rage on your co-workers around 4 pm, or C. Skip lunch 😦
What if I told you that there was a fourth option, one that allowed you to eat your entire lunch and not feel drowsy? Impossible you might say, but a study from Dr. Alpana Shukla at Weill Cornell Medical College highlights a quirk of our digestive systems that we might be able to utilize to fight the food coma.
First, it’s important to understand why we feel tired after eating. While there are likely many factors that contribute to feeling tired postprandially (after eating a meal), one factor that carries particular importance is blood glucose levels. When blood glucose levels are low, there is less energy being delivered to the body and the brain, which leads to tiredness.
After a meal, a healthy individual’s blood glucose will increase at first from all the glucose being absorbed from their food. But while blood glucose is what supplies energy to the brain and body, it can lead to adverse effects if it gets too high. In order to stop blood glucose from going too high after a meal, the pancreas releases a hormone called insulin, which signals cells to take glucose out of the blood and store it. Insulin protects us from the harmful effects of hyperglycemia (high blood glucose). When insulin doesn’t work properly, like in people with diabetes, additional insulin may be required to prevent hyperglycemia after a meal.
The problem with insulin is that it can overshoot. Like the school cafeteria overcooks Brussel sprouts, insulin can causes blood glucose to go lower than the ideal range. The reason for this overshoot, or reactive hypoglycemia (“hypo-” = low) is because insulin acts a little bit longer than it needs to, and it takes a while for the body to shut off insulin once it does its job. This reactive hypoglycemia contributes, along with other factors, to the post-meal slump that knocks us out after lunch.
So how can we prevent reactive hypoglycemia while still eating? One way that Dr. Shukla has found is to eat your carbs last. In her study, she had her participants with prediabetes eat a set meal of ciabatta, grilled chicken, and vegetables in varying orders. The carbs-first group eats their bread over 10 minutes, takes a 10-minute break, and then eats the chicken and vegetables over 10 minutes. The protein-and-vegetables-first group eats their chicken and vegetables over 10 minutes, takes a 10-minute break, and then eats the ciabatta over 10 minutes. Lastly, the vegetables-first group eats their vegetables over 10 minutes, takes a 10-minute break, and then eats the chicken and ciabatta over 10 minutes. Everyone’s blood glucose levels were assessed every 30 minutes at the start of the meal until 3 hours after the meal.
The protein-and-vegetables-first and the vegetables-first groups both had relatively stable blood glucose levels which did not spike or dip sharply, but the carbs-first group experienced a much higher blood glucose spike and subsequent dip below baseline. These results suggest that eating protein and vegetables first (and thus carbs last), can help stabilize the spike and dip in blood glucose levels after a meal, which may help to even out energy levels as well.
For your meal of salmon, salad, and rice, this study suggests that eating your salmon and salad first and rice last might be helpful in preventing the dreaded post-meal slump. While that might not seem like normal behavior and you could be tired due to other reasons (sleep deprivation, caffeine withdrawal, etc), this new finding in nutrition research may just help you stay awake during that 2 pm presentation.
Peer-edited by Gabrielle Dardis, PhD Candidate in Biochemistry
Picture Credit: Cover photo and text photo found on Shutterstock. Graphic from Shukla et al. 2019.
1. Shukla AP, Dickison M, Coughlin N, Karan A, Mauer E, Truong W, Casper A, Emiliano AB, Kumar RB, Saunders KH, Igel LI, Aronne LJ. The impact of food order on postprandial glycaemic excursions in prediabetes. Diabetes Obes Metab. 2019 Feb;21(2):377-381. doi: 10.1111/dom.13503. Epub 2018 Sep 10. PMID: 30101510; PMCID: PMC7398578.
2. Reactive hypoglycemia: What causes it? – Mayo Clinic. Retrieved October 12, 2021, from https://www.mayoclinic.org/diseases-conditions/diabetes/expert-answers/reactive-hypoglycemia/faq-20057778