Why protein keeps you more alert (and thinner) than sugar does

Your new afternoon snacks?

It’s 3PM and you’re at your desk fighting determinedly to keep your eyes open. You think maybe some candy or soda could give you the sugar rush you need to get through the last few hours of the work day, so you head to the vending to get some — STOP! Wait a minute. You might want to read this post first before you snag those M&M’s; new research shows that protein might do a better job of keeping you awake, and burning your calories, too.

As someone who’s happiest with meat at every meal, I say: pass me the jerky.

Everyone’s familiar with the concept of a sugar rush: you eat a ton of sweet stuff, you get a huge rush of energy and hyperactivity, and then you “crash” and feel more tired than you did before eating the sweets. That said, it’s almost logical to think that sugar would stimulate cells that help keep us awake. What cells are those? They are neurons called orexin cells, which secrete a stimulant into the brain to help keep us awake and burn calories. In fact, these neurons are less active in obese people and narcoleptics.

Researchers in the U.K. set out to find what makes these drowsiness-busting, calorie-burning neurons tick. They labeled the orexin neurons in mouse brains using genetically-directed fluorescence; this way, they could introduce different types of nutrients and look at their effects on the activity of only the orexin neurons. Interestingly, glucose was found to inhibit these cells, which might explain after-meal sleepiness when the sugar from your food gets into your blood and then to your brain. In a recent follow-up publication, this same group found that dietary amino acids, like the ones found in egg whites, stimulated orexin neurons — these amino acids even reversed the inhibitory effect of glucose.

In other words, and to vastly oversimplify, sugar might contribute to making you sleepy and stout, while protein could help to keep you lively and lean. These findings could to explain previously mystifying studies in which protein meals made people more alert than carbohydrate meals. Additionally, these results could be especially important for altering the dietary compositions of people with disorders like obesity, insomnia, and narcolepsy.

So, if you swap out a candy bar for a protein bar with the same number of calories, the protein might tell your body to burn more of those calories, and you’ll get through your day with fewer yawns. Sounds like a good trade to me.

Stay nerdy.

Burdakov D, Gerasimenko O, & Verkhratsky A (2005). Physiological changes in glucose differentially modulate the excitability of hypothalamic melanin-concentrating hormone and orexin neurons in situ. The Journal of neuroscience : the official journal of the Society for Neuroscience, 25 (9), 2429-33 PMID: 15745970

Karnani MM, Apergis-Schoute J, Adamantidis A, Jensen LT, de Lecea L, Fugger L, & Burdakov D (2011). Activation of central orexin/hypocretin neurons by dietary amino acids. Neuron, 72 (4), 616-29 PMID: 22099463