Post-Lunch Crash? Take the Protein Detour


The battle with drowsiness ensues in the hour after lunch. When there’s work to be done, struggling to pay attention and focus on the task at hand, we often turn to caffeine as our savior. But is there another way? Can we minimize or prevent the post-lunch crash? Why does it even happen at all?  

There’s the common myth that a full belly makes the blood rush to our stomachs and out of our brains, depriving our brain cells of oxygen and other vital nutrients. But unless every meal results in brain damage, which is then magically reversed an hour or two later, perhaps comatose isn’t the best way to describe our post-meal state. The makeup of the meals we eat affects the chemicals within our brain, and has direct physiological impacts. 

Serotonin and melatonin are two brain messenger molecules, or neurotransmitters, which have a calming effect and help maintain our sleep-wake cycle. The brain produces both molecules using tryptophan as starting material. Tryptophan is first chemically altered to produce serotonin, which is then converted into melatonin. 

The tryptophan in turkey is often associated with the post-Thanksgiving meal slump. This myth persists even though turkey contains less tryptophan than more than 50 other foods, including eggs and spinach. In actuality, the holiday over-consumption of carbohydrate-rich breads, pies, and biscuits is largely to blame. 

Think of a pond in which your blood is like the water, and amino acids are like the fish. At any given time there are 20 different amino acids swimming around. The surge of insulin after a carb-heavy meal pulls the majority of these amino acids into the muscles, much like fisherman pulling fish out of a pond. Not taking the bait, tryptophan is left behind. The brain, getting hungry, casts its own net, and catches the tryptophan – drowsiness ensues. 

However, there is a remedy. According to a study from the Massachusetts Institute of Technology, including at least 10 percent protein in a meal begins to lower the entry of tryptophan into the brain, and the more protein in your meal, the better. Protein is made up of many different types of amino acids. When you release these various types of amino acids into the pond, the chances of catching tryptophan greatly diminishes, preventing its sedative effects.

A protein-rich meal also increases brain levels of a different amino acid called tyrosine. According to researchers from the U.S. Army Research Institute of Environmental Medicine, tyrosine elevates the production of other neurotransmitters, mainly dopamine and norepinephrine. 

Dopamine is involved in regulating our attention and our ability to focus. Medications prescribed to patients with attention-deficit disorder elevate dopamine availability in the brain. This clearly illustrates dopamine’s ability to influence our mental state. Due to its involvement in alertness, attention, movement, and various types of learning and memory, dopamine has been studied for decades.

Norepinephrine, also known as noradrenaline, is also important for attention. Imagine: you’re walking down the street, alone. It’s dark. You spot a shadowy figure walking in your direction a few hundred steps ahead. A rush of alertness spreads throughout your body.  As you near the shadowy figure, your heart and mind begin to race. “Should I keep walking? Should I turn off? Should I turn around and run?” In this scenario a large dose of norepinephrine is released into your brain during fight-or-flight, a response to situations in which alertness and attention are critical to our survival. A protein-rich meal releases a much smaller dose of norepinephrine, leaving your heart rate normal and your wit about you, but non-the-less contributing to alertness.

Understanding how our eating habits affect cognitive performance can help us combat the post-lunch dip and elevate productivity naturally, without diminishing our capacity to be productive. This eliminates the need to drink excessive amounts of caffeine or other chemicals – which have side effects or ultimately lead to a crash and a decline in mental performance.  Next time you’re grabbing lunch on a busy day, remember, avoid the carb crash, and take the protein detour. 



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