Carbs or Protein After a Workout?

Post-workout carbs or protein

I received this question in an email and thought it would make for a good blog post, as it’s a question I receive quite often. If you have something you’d like to see answered, feel free to send a question through the contact page.

Post-workout nutrition choices play a significant role in your ability to recover, build muscle, reduce muscle soreness and even help keep you from getting sick. As important as this “window of opportunity” is, recommendations for what to eat or drink are still surrounded in myth and misunderstanding.

Post-workout nutrition became popularized with research by John Ivy and his team, who later published an appropriately titled book, Nutrient Timing. The very short summary of his findings was that a post-workout meal or shake consisting of carbs and protein, in a ratio of 4:1, seemed to provide the right mix to maximally stimulate glycogen (carbohydrate) repletion and increase protein synthesis.

The downside of the work was that it was primarily focused on athletes and speeding recovery between training sessions. It was not focused on the average person who exercises for health and fitness.

Many sports nutrition companies took Ivy’s research and promoted the 4:1 carb-to-protein post-workout recommendation for everyone. Go for a walk, have a high-carb shake or meal. Play in a softball game (where you stand still most of the time) and have a high-carb shake or meal. Do a basic strength training session and have a high-carb shake or meal.

Non-athletes rarely need to use such a strategy. In fact, for those looking to increase muscle, while minimizing fat gains, such a high-carb, low-protein post-workout option can be detrimental.

Even worse, advertising for supplements and snacks related to exercise send the message that lots of carbs are good. The exaggerated advertising creates an unwarranted excuse to indulge in carbs with reckless abandon following a workout. Then people scratch their heads, wondering why they’re not getting leaner with all the exercise they’re doing.

Post-workout nutrition strategies for an athlete have different objectives than the objectives of post-exercise nutrition for health and fitness focused people.

The use of protein and carbohydrates, following a workout, are generally recommended for the following reasons:

  • To enhance glycogen replenishment
  • To stimulate protein synthesis
  • To reduce muscle protein breakdown
  • To speed recovery between workouts
  • To support immune function

The question then becomes, “Do your fitness goals and training program drive the need for post-workout carbs and/or protein?”

Post-Workout Carbs and Glycogen Replenishment

As intensity levels of a training session increase, glycogen, or carbohydrate usage, increases. Intensity increases by running, swimming or cycling faster. Intensity can also be increased by performing more sets or reps during a resistance training workout. In fact, during moderate to high-rep-range resistance training performed to muscular failure, glycogen can be depleted by 25-40%.[1] Low-rep, heavy weight training doesn’t tap into glycogen stores very much, as the primary energy source is ATP and creatine phosphate.

Since exercise depletes glycogen, it stands to reason that post-workout carbohydrates would help replenish glycogen levels. While it’s true that post-workout carbs effectively replenish glycogen stores, the question is, “Are they necessary?” Do you really need to immediately replenish glycogen stores after a workout, or will your normal diet refill your glycogen stores during the time between exercise sessions? If so, the post-workout carbs probably aren’t necessary.

If you’re training a couple times per day, you’d be well-justified in using carbs right after your workout. You’ll be far more prepared for your second training session of the day. Think of a football player during training camp. More than likely, that isn’t you.

Chances are, you’re not training twice a day. You have a full-time job, family commitments and many other things going on. You train three to five times per week. If you train more than three times per week, you probably follow a split routine, where you’re not training the same muscle group with a high level of volume more than once every few days.

If that sounds more like you, your body will have plenty of time to replenish most of its glycogen stores between workouts by eating a ton of vegetables and some fruit, without loading up on carbs after your workout.

The bottom line here is, if your training volume and frequency is high, you could benefit from a higher-carb post-workout strategy to help you perform well at your next workout. If your training is moderate in intensity or volume, you probably don’t need the carbs for glycogen replenishment.

Post-Workout Carbs and the Insulin Spike

Post-workout carbs spike insulin levels. When insulin levels are high, nutrients may be shuttled into the cells to speed recovery at a faster rate. It sounds good, but elevated insulin also shuts down fat burning. In a short period of time following the carb intake, blood sugar levels drop, stimulating hunger and low energy levels.

The question I weigh out here is, “Is the small increase in nutrient absorption more beneficial than the side effects of the carbs consumed after a workout?” For those who are strictly training to improve performance, I’d definitely say “yes.” For those who are pursing optimal health and body fat levels, while accepting a small drop in performance, I’d say “no.”

Post-Workout Protein

While exercise is a good thing, you don’t get stronger, more muscular or fit during your training session. This all occurs during the recovery process following a training session. In fact, during a training session, you actually become weaker as you fatigue and breakdown muscle tissue. Where the body has an ability to replenish carbohydrate needs on its own, it can’t do the same with protein. Protein needs must be met with food or supplements.

Protein is king when it comes to recovery. Protein helps build muscles, supports the immune system, satisfies hunger and supports a number of other metabolic functions.

It was once thought that raising insulin by consuming carbohydrate helped improve net protein balance, but research shows the effects are minimal, if they at all. If the carbohydrates do have any effect, it’s from raising insulin, which may slow protein breakdown slightly.

However, protein does stimulate protein synthesis and reduces protein breakdown following a training session. In doing so, protein creates a net increase in lean body mass.

Protein or amino acids have also been shown to reduce soreness and muscle damage following a training session. Interestingly, a study on U.S. Marines showed post-workout protein led to fewer medical visits, bacterial infections and muscle or joint problems.[2]

The need for post-workout carbs varies based on the individual, but everyone benefits from protein during the post-workout window.

Protein also raises insulin levels, though nowhere near to the extent that carbohydrates do. But their mild stimulation of insulin may offer the small benefit of reduced protein breakdown seen with insulin increases from carbohydrate.

Whey protein has a strong track record in research as a superior post-workout protein source. Compared to soy or casein, whey protein stimulates the growth of lean body mass much better. Part of this is due to its rich source of branched-chain amino acids, and part of it is due to its fast digestion and absorption. Whey isolate is the most frequently researched form of whey protein for performance enhancement.

A serving of 20 grams of whey protein seems to maximally stimulate protein synthesis, meaning 40 grams of protein doesn’t further stimulate protein synthesis. However, this does not take into account the effects that greater protein intakes have on lowering protein breakdown. At a minimum, I’d recommend 20 grams of protein from whey following a training session, but would not dissuade someone from consuming more.

There has also been little research showing how other protein sources compare to the effects of 20 grams of protein, other than the soy or casein mentioned above. In my opinion, I’d err on the higher end of protein intake following an exercise session, especially with protein sources other than whey.

Post-Workout Protein Plus Carbohydrate

Separately, carbohydrates replenish glycogen stores following exercise, which is necessary in some people. Protein does a bunch of important stuff following exercise, which is important for virtually  everyone.

If they’re consumed together, is there some kind of synergistic effect? No, not really.

Combining carbohydrates with protein does not further improve glycogen stores than when carbohydrates are consumed alone.

Carbohydrates do suppress protein breakdown slightly, when combined with protein, which helps improve net protein balance. But this comes at a trade-off of potential reductions in fat utilization and cravings for more carbs. Protein synthesis is not improved by adding carbs to the protein. The minor benefit of adding carbs to protein for average individuals isn’t worth the potential drawbacks.[3]

The combination of protein and carbs is really appropriate for those individuals who need quick glycogen replenishment along with the benefits protein provides. Who really needs that? Athletes and those training with high frequency and intensity.

If you’re like me, exercise is something you do for an hour or so most days of the week. You’re conscious of minimizing body fat gains. You’re main goals are to maintain optimal health while looking and feeling fit. If that’s the case, stick with protein.

Thanks for reading. Have a question or comment? Post it below.