Myth: Take Carbs Post-Workout To Spike Insulin For Greater Muscle

Many people think that it’s necessary to consume carbohydrates after a workout in order to elevate insulin and maximize muscle growth.

In fact, the extra insulin due to carb supplementation has no additive effect on protein synthesis. A recent study found there was no difference in muscle protein synthesis or protein balance when 25 grams of whey protein or the same dose of whey protein with 50 grams of carbs were supplemented after strength training (6).

It should be noted that an elevation of insulin above fasting levels has an anti-catabolic effect on muscle tissue, but this degree of increase can be achieved with whey protein (7). This is important because if your goal is to lose body fat, you don’t want to replace all the calories you just burned doing a hard workout by consuming unnecessary carbs.

That said, it’s worth mentioning that if you’re a hardcore athlete who trains multiple times a day, carb supplementation post-workout will enhance glycogen restoration in the muscle. Glycogen is your muscle’s energy source and it can make or break athletic performance when repeated high volume, intense bouts of exercise are necessary, such as when playing in a basketball or soccer tournament or doing two-a-days for an extended period of time.
For everyone else, unless you are severely restricting carbs in your diet for some reason, glycogen will easily be replenished from regular meals and supplementation is not necessary (7).

To avoid any confusion, another issue worth clarifying is our recommendation that post-workout is one of the best times to eat carbs. If you’re on a lower carb diet with the goal of losing body fat, the hours after your workout are one of the best times to eat carbs because insulin sensitivity is greatly enhanced. The body will digest carbs into glucose in the blood and then store those calories as glycogen in the muscle. However, if you eat carbs at other inopportune times, such as for breakfast, when glycogen stores are full, it’s more likely that those calories will be stored at fat.

Take Away: There’s no need to consume supplemental carbs post-workout to maximally trigger protein synthesis. A whey protein shake containing 20 grams will do the trick and save you carb calories if your goal is fat loss.

References
1. West, D., Kujbida, G., et al. Resistance Exercise-Induced Increases in Putative Anabolic Hormones Do Not Enhance Muscle Protein Synthesis of Intracellular Signaling In Young Men. 2009. Journal of Physiology. 587(21), 5239-5247.

2. West, D., Burd, N., et al. Elevations in Ostensibly Anabolic Hormones with Resistance Exercise Enhance Neither Training-Induced Muscle Hypertrophy Nor Strength of the Elbow Flexors. 2010. Journal of Applied Physiology. 108, 60-67.

3. Frank, A., et al. The role of hypothalamic estrogen receptors in metabolic regulation. Frontiers in Neuroendocrinology. 2014. 35(4):550-7.

4. Ignacio, D., et al. Thyroid hormone and estrogen regulate exercise-induced growth hormone release. PLOS One. 2015. 10(4):e0122556.

5. Lizcano, F., Guzman, G. Estrogen Deficiency and the Origin of Obesity during Menopause. Biomedical Research International. 2014. 2014:757461.

6. Staples, A., et al. Carbohydrate does not augment exercise-induced protein accretion versus protein alone. Medicine and Science in Sports and Exercise. 2011. 43(7):1154-61.

7. Aragon, A., Schoenfeld, B. Nutrient Timing Revisited: Is There a Post-Exercise Anabolic Window? Journal of the International Society of Sports Nutrition. 2013. 10(5).