I’m sure that you've heard this phrase in the past 17 minutes: "Carbs release insulin and that will make you a fat bastard.” Really? Is there a way to use these evil insulin secreting carbs to enhance your training performance for more muscle and less fat?

It's a bioenergetic fact that a vast majority of your high volume training in the gym is fueled by carbohydrates (5). As you exercise at a higher intensity, the main fuel that your body uses is carbohydrates, mainly from stored glycogen in the liver and muscles. Ask anyone who has tried a very low carb or ketogenic diet how their training went a few weeks into it. I rest my case.

Because carbs are the main fuel, dramatically restricting them isn't the best idea for the stimulation of muscle. But going bonkers on carbs at every single meal and washing them down with a large Slurpee and a side of four Pop-Tarts® isn't the best for body composition. There can be a happy medium by placing more carbs right before your training. You already know that consuming protein is beneficial (4, 11, 12, 15), but carbs have their place here, too.

Here are four reasons for placing a bunch of your carbs before your next hard training session.

back pulldown marshall nelson pre carb 102314

#1 Insulin

Insulin’s reputation is worse than Mylie Cyrus’s PR after a bad twerking experiment. Insulin has been described as everything from the most anabolic hormone to the reason why you add fat by just looking at a doughnut. What gives?

Much of the information surrounding insulin is just flat out wrong. Insulin can be best thought of as the fuel selector switch. When your insulin levels are high, it will push your body to use carbohydrates. When your insulin levels are low, it will push the body to use more fats.

  • High insulin --> use carbs
  • Low insulin --> use fat

Insulin has a lot of metabolic leverage—large effects with less effort. Not only does it result in physiologic changes, but it is under your control from a nutritional standpoint. Long term, you want to have periods of lower insulin to push the body to use fats (metabolic flexibility), but before you go lift bone-crushing weights in the gym isn't one of those times. High intensity training is fueled primarily by ATP-PC and carbohydrates.

A great time to consume carbohydrates along with a fast-acting protein to bump up muscle protein synthesis is just before training. Dr. Burke and colleagues showed that pre-training ingestion of a whey protein increased muscle protein synthesis for five hours [compared to a placebo (6)].

This mixture of protein and carbohydrates pre-training will increase insulin levels and push your body toward the main fuel that you want to drive your training—glycogen (stored carbs). This form of nutrition periodization matches the incoming fuel source with the fuel that you want to use during that training session [i.e. nutrient matched training (NMT)].

#2 Less muscle breakdown

The second reason for pre-training carbs is that insulin has been described as an anti-catabolic agent. It decreases protein degradation. This has been shown in extreme cases of muscle breakdowns like with burn patients (2) and also healthy humans (7).

In a super cool wizzbang tracer study, Chow (7) demonstrated that in healthy humans at rest, insulin did not stimulate muscle protein synthesis, but it did decrease protein breakdown. In that study (7), insulin achieved a net muscle protein anabolic response (more muscle) by inhibition of muscle protein breakdown.

front raise nelson carbs pre 102314

Remember, more muscle protein synthesis and less protein breakdown equals more muscle tissue. I can have more money left over from a night in Vegas if I either win more money (unlikely) or spend less (equally unlikely), but you get the picture.

Insulin only seems to further increase protein synthesis at pharmacological doses (which is not recommended), although it does help decrease the amount of protein you breakdown. Thus, the net effect is more muscle.

#3 Easy calories

Consumption of a protein and carbohydrate beverage before training is a very easy way to increase the amount of calories.

For optimal performance, you need both raw materials and energy. Think of building your body as building a home. In order for the brick layers to make bricks and build your new house of muscle, bricks and energy are required. All the bricks (protein) in the world won’t do you any good without any fuel. The brick layers need fuel for the machines.

Adding a protein and carb drink before your training is an easy way to cover the fuel (carbs) and building materials (protein) in minutes.

#4 Better pumps

Want to get a great pump in the gym next time? Up the carbs! Even Dave Tate has discussed the importance of old school bodybuilding training for powerlifters when doing supplemental and accessory work. It has been shown that an insulin infusion has a direct vasodilation effect (17) via nitric oxide. The more blood that flows into the muscle and gets trapped there, the better pump and more muscle growth (14) you'll get. Cleland and colleagues (8) demonstrated that vasodilation and glucose uptake are highly related.

By consuming carbohydrates pre-training, you're increasing insulin levels and enhancing vasodilation. Increases in muscle blood flow have been demonstrated at physiological levels of insulin (1, 9, 18). Still don’t believe me? Try doing a very low carbohydrate diet and see what happens to your pump in the gym. You can thank me later.

triceps grant nelson pre carb 102314


Macronutrients serve three main purposes: energy, building blocks and signaling (3, 10, 13, 16). When insulin is increased before training, it signals your body to use more carbohydrates. These carbohydrates also provide a fuel source for your training and can decrease the amount of muscle that is broken down. As a bonus, insulin-induced release from carbohydrates results in increased vasodilation for a greater pump. Now get some carbs and get to the gym!


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    2. Ballian N, Rabiee A, Andersen DK, Elahi D, Gibson BR (2010) Glucose metabolism in burn patients: the role of insulin and other endocrine hormones. Burns 36(5):599–605.
    3. Bartlett JD, Louhelainen J, Iqbal Z, Cochran AJ, Gibala MJ, Gregson W, Close GL, Drust B, Morton JP (2013) Reduced carbohydrate availability enhances exercise-induced p53 signaling in human skeletal muscle: implications for mitochondrial biogenesis. Am J Physiol Regul Integr Comp Physiol 304(6):R450–8.
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    7. Chow LS, Albright RC, Bigelow ML, Toffolo G, Cobelli C, Nair KS (2006) Mechanism of insulin’s anabolic effect on muscle: measurements of muscle protein synthesis and breakdown using aminoacyl-tRNA and other surrogate measures. Am J Physiol Endocrinol Metab 291(4):E729–36.
    8. Cleland SJ, Petrie JR, Ueda S, Elliott HL, Connell JM (1999) Insulin-mediated vasodilation and glucose uptake are functionally linked in humans. Hypertension 33(1Pt 2):554–8.
    9. Clerk LH, Vincent MA, Jahn LA, Liu Z, Lindner JR, Barrett EJ (2006) Obesity blunts insulin-mediated microvascular recruitment in human forearm muscle. Diabetes 55(5):1436–42.
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    11. Coffey VG, Moore DR, Burd NA, Rerecich T, Stellingwerff T, Garnham AP, Phillips SM, Hawley JA (2010) Nutrient provision increases signaling and protein synthesis in human skeletal muscle after repeated sprints. Eur J Appl Physiol.
    12. Hawley JA, Burke LM, Phillips SM, Spriet LL (2010) Nutritional modulation of training-induced skeletal muscle adaptation J Appl Physiol.
    13. Li F, Yin Y, Tan B, Kong X, Wu G (2011) Leucine nutrition in animals and humans: mTOR signaling and beyond. Amino Acids 41(5):1185–93.
    14. Loenneke JP, Fahs CA, Rossow LM, Abe T, Bemben MG (2012) The anabolic benefits of venous blood flow restriction training may be induced by muscle cell swelling. Med Hypotheses 78(1):151–4.
    15. Moore DR, Robinson MJ, Fry JL, Tang JE, Glover EI, Wilkinson SB, Prior T, Tarnopolsky MA, Phillips SM (2009) Ingested protein dose response of muscle and albumin protein synthesis after resistance exercise in young men. Am J Clin Nutr 89(1):161–8.
    16. Stipanuk MH (2007) Leucine and protein synthesis: mTOR and beyond. Nutr Rev 65(3):122–9.
    17. Su EN, Yu DY, Alder VA, Cringle SJ, Yu PK (1996) Direct vasodilatory effect of insulin on isolated retinal arterioles. Invest Ophthalmol Vis Sci 37(13):2634–44.
    18. Vollenweider P, Tappy L, Randin D, Schneiter P, Jequier E, Nicod P, Scherrer U (1993) Differential effects of hyperinsulinemia and carbohydrate metabolism on sympathetic nerve activity and muscle blood flow in humans. J Clin Invest 92(1):147–54.

Mike is an adjunct professor and a member of the American College of Sports Medicine.