Chocolate Milk Is Not A Performance Enhancing Drug

For more than a few years now, we’ve been hearing about the amazingness of chocolate milk as a post-workout recovery drink. There was a lot of initial hubbub, then things kind of quieted down a bit….and if you were paying attention/didn’t have your chocolate-blinders on, maybe you noticed that more than a few people were grumbling about the #spon hashtags that often accompanied the continued chocolate milk plugs. A lot of triathletes probably went back to their trusty Ultra-dur-en-oxy-recov-erox or what-have-you drink, because if it has a long fancy name with exercise-y sounding syllables, it must be the most technologically advanced recovery drink out there, and your ticket to Kona Qualification. Maybe the chocolate milk got shoved to the back of the fridge (somewhere behind the beets, pickle juice, and bovine colostrum).

But now our Kona champ is advertising for chocolate milk.

Somewhere deep in the logical area of your brain, you know that the pros often plug products they don’t use, that just because something works for one person doesn’t mean it will work for you, and that chocolate milk is probably not the secret ingredient to a world championship. But your triathlete brain wants to run to the grocery store and get some anyway.

But should you? Let’s take a look.

Does it work, and is it any better?

photo credit: http://www.flickr.com/photos/44124379481@N01/104952950 via photopin.com

Several controlled trials have put chocolate milk to the test. In the first, 10 “regional-level” cyclists and triathletes completed a high-intensity interval training session, then consumed either a chocolate milk or carb replacement beverage (matched for caloric content). 15-18 hours later, they cycled at 85% maximal oxygen uptake until they couldn’t cycle any more. This protocol was repeated the following week with whatever beverage each participant didn’t use the first time around (important, because this allows us to compare carb beverage vs chocolate milk within the same person). What were the results? No significant differences in time to exhaustion, and no differences in reported muscle soreness afterwards.¹

Similar results were found when testing soccer players during a period of increased training load – when consuming chocolate milk vs. a matched-calorie carb beverage, no differences were seen in players’ muscle soreness, fatigue ratings, quadriceps muscle force produced, or myoglobin levels (myoglobin is a protein in muscle released into the bloodstream after muscle damage – so it can be considered a rough marker of “recovery”).²

Ok, so that’s a couple of studies showing no advantage of chocolate milk over your average carb replacement drink in terms of exhaustive exercise performance, soreness, fatigue, and post-training muscle damage (but note, no explicit detriment to using chocolate milk either).

But…chocolate milk has protein, and carb-only beverages don’t (duh). So there must be a difference somewhere, right?

Another study had male runners run for 45 minutes at 65% of their VO2 peak, then drink either chocolate milk or a calorie-matched carb beverage (and as before, repeated this 1 week later with the opposite beverage). Then they took muscle biopsies of the poor souls who signed themselves up for this study. Muscle glycogen repletion post-exercise wasn’t any different between carb-only vs milk, but they did see effects on signaling molecules of skeletal muscle protein turnover, leucine (an amino acid) kinetics, and FSR with milk compared to the carb-only beverage. This just shows what we’ve known for a while – carb + protein has some advantages over carb-only specific to protein synthesis (at least at the molecular level) post-exercise (nerds: for a nice review, see this article).³ On the other hand, a recent study of “recreationally active” men who drank either chocolate milk – daily – or a placebo beverage (matched for calories and carbs) during 12 weeks of resistance training showed no differences in muscle hypertrophy⁴ – so the extra 8 grams of protein in chocolate milk might not be that advantageous on a macroscopic level.

So where did all this hype come from?

One study, done in 2009, on 9 trained male cyclists who completed a time trial followed by 4 hours of recovery, during which they consumed either chocolate milk, a calorie-matched carb replacement beverage, or fluid replacement only. Then they cycled to exhaustion at 70% of max oxygen uptake. Under this protocol, the authors found significantly increased performance (43-51% longer time to exhaustion) after chocolate milk compared to carb or fluid replacement only.⁵

So what could explain the difference here? First, there was no sucrose in the carb-only beverage; the “Mars Refuel chocolate milk” used here contained glucose, fructose, sucrose, and lactose – so not necessarily your average chocolate milk. It’s possible that part of the performance difference could be explained by different carb types.

Second, the advantages of Mars Refuel chocolate milk could be specific to subsequent performance at lower exercise intensities (60-70% VO2 max, as was used in this study). Think about it – we focused on protein before, but milk also has some fat content, and at this exercise intensity, you’re going to be oxidizing a higher proportion of fatty acids.

Third, there’s this disclaimer at the end of the paper. Now, plenty of great, objective research is funded by industry – but it’s still important to at least consider that someone with skin in the game bank-rolled the study.

So what have we concluded so far?

(1) There’s no convincing evidence that chocolate milk is advantageous as a post-workout drink. But (2) there’s also no evidence that it’s performance de-enhancing, compared to other beverages (unless you’re lactose intolerant, of course, but we won’t go there). So what’s the big deal?

Obligatory Health Soapbox:

1. Your average cup of chocolate milk contains ~25 grams of sugar, about the same as a soda. Half of that is from lactose, the other half is added (cane sugar, high fructose corn syrup, organic coconut sugar – your body treats it basically the same).

2. Lactose (naturally occurring sugar in milk) isn’t absorbed spectacularly by a lot of adult digestive systems, and most likely, you’ve already harangued your gut with some sort of gel/drink mix/etc during your workout – so if you’re a sensitive GI type, you may be adding insult to injury.

3. Sure, you’re getting some Vitamin D, calcium, and protein in that milk, which is great. But in that case, why not just drink #whitemilk? Trust me, the whey protein and lactose alone will be more than enough to spike your insulin (such that your body appropriately replenishes your muscle glycogen and gets some protein synthesis started) without the added pre-diabetes. Yes, that can happen to people who exercise a ridiculous amount too.

photo credit: http://www.flickr.com/photos/45968460@N03/5456102904 via photopin.com

For the record, I don’t categorically hate sugar. And from a health standpoint, if you’re going to indulge, after a workout is a great time. My point is, don’t delude yourself into thinking chocolate milk is an inherently healthy beverage. It’s basically liquid chocolate ice cream. Mmmm….

One last final note: Why Do We Want to Believe in the “Benefits” of Chocolate Milk So Much?

When you consume a palatable food (no joke, chocolate milk is often used in these studies – almost universally liked & easy to drink while having your head scanned), the regions of your brain that are involved in anticipating and processing rewards strongly activate (like the orbitofrontal cortex, insula, and putamen, for those curious). You also have a big release of dopamine, the feel-good neurotransmitter.

So blame it on your brain: it likes sugar. A lot. You even think about chocolate milk, and those reward-related brain regions probably light up like a light bulb. And maybe this plays into why we want to be able to health-wash chocolate milk.

1. Pritchett, K., Bishop, P., Pritchett, R., Green, M., & Katica, C. (2009). Acute effects of chocolate milk and a commercial recovery beverage on postexercise recovery indices and endurance cycling performance.Applied Physiology, Nutrition, and Metabolism,34(6), 1017-1022.
2. Gilson, S. F., Saunders, M. J., Moran, C. W., Moore, R. W., Womack, C. J., & Todd, M. K. (2010). Research article Effects of chocolate milk consumption on markers of muscle recovery following soccer training: a randomized cross-over study.
3. Lunn, W. R., Pasiakos, S. M., Colletto, M. R., Karfonta, K. E., Carbone, J. W., Anderson, J. M., & Rodriguez, N. R. (2012). Chocolate milk and endurance exercise recovery: protein balance, glycogen, and performance.Med Sci Sports Exerc,44(4), 682-91.
4. Mitchell, C. J., Oikawa, S. Y., Ogborn, D. I., Nates, N. J., MacNeil, L. G., Tarnopolsky, M., & Phillips, S. M. (2014). Daily chocolate milk consumption does not enhance the effect of resistance training in young and old men: a randomized controlled trial.Applied Physiology, Nutrition, and Metabolism,40(2), 199-202.
5. Thomas, K., Morris, P., & Stevenson, E. (2009). Improved endurance capacity following chocolate milk consumption compared with 2 commercially available sport drinks.Applied Physiology, Nutrition, and Metabolism,34(1), 78-82.
6. Kringelbach, M. L., O’Doherty, J., Rolls, E. T., & Andrews, C. (2003). Activation of the human orbitofrontal cortex to a liquid food stimulus is correlated with its subjective pleasantness.Cerebral cortex,13(10), 1064-1071.