You don’t need carbs after a workout to build muscle. While the rapid provision of carbohydrate after exercise is important for some people in certain situations, for most people (which likely includes you), it isn’t.
Here’s a closer look at what the science has to say on the subject of post-workout carbs and muscle growth.
Making the Case for Carbs After a Workout
If I wanted to make a case for the importance of taking in carbs after a workout, it would go something like this:
After a tough workout, your body is depleted of glycogen – the name given to carbohydrate stored in your body – which needs to be replaced as soon as possible. Failure to do so is cheating your muscles and putting the brakes on recovery.
Stored glycogen in muscle cells will also pull water into those cells. This increases cell volume, triggering changes in the muscle that will ultimately lead to faster growth.
The best way to do this is with a rapidly digested carbohydrate with a high glycemic index. Potatoes, rice, dextrose, maltodextrin, waxy maize starch or Vitargo will all do the job.
The carbs also jack up your insulin levels, which helps to shuttle nutrients into muscle cells, as well as blocking the post-exercise rise in cortisol levels, which would normally have a catabolic effect on your muscles.
In short, to truly maximize recovery and muscle growth, carbs after a workout are essential.
Insulin will be spiked, cortisol will be shut down, muscle tissue damage will be repaired and glycogen will be restored as the post-workout gods deliver you directly to recovery heaven.
Or will they?
Actually, they won’t.
Post-Workout Nutrition and Glycogen
It’s true that muscle glycogen is synthesized more rapidly if you take in some carbs immediately after a workout rather than several hours later.
In fact, delaying the consumption of post-workout carbs for just two hours has been shown to slow the rate of muscle glycogen resynthesis by as much as 50% .
Put differently, the speed of post-exercise glycogen synthesis is not important as long as the total carbohydrate need for the day is met.
Unless you’re doing multiple daily workouts, a decent muscle-building diet will provide enough carbohydrate to restore glycogen stores regardless of what your post-workout nutrition looks like.
Think of it like putting fuel in your car.
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Unless you were taking part in a race, the rate at which the pump dispenses the fuel into your car is of very little practical significance.
What’s most important is the amount of fuel that gets into the tank, rather than the speed at which it gets in there.
Post-workout nutrition is a different story if you’re involved in a sport or activity where the length of time between exercise is relatively short.
The training practices of some athletes, for example, will often demand multiple bouts of exercise targeting the same muscle groups on the same day.
In this case, speeding up the rate of glycogen replenishment takes on a much greater importance . You want those muscles ready for action again as soon as possible.
In other words, the speed of glycogen restoration is important for some people in certain circumstances.
But for most of us, it isn’t.
Do You Need Post-Workout Carbs to Build Muscle?
The idea that you need carbs after a workout to “spike” insulin levels and gain muscle is also a myth.
But this has little to do with changes in blood sugar levels. Rather, the amino acids in whey trigger insulin secretion directly in pancreatic beta cells. The branched-chain amino acids, leucine in particular, appear to be the most potent insulin secretagogues.
Whey also stimulates the release of a couple of gastrointestinal hormones known as GIP and GLP-1, both of which have the effect of raising insulin levels .
In one study, taking 50 grams of carbohydrate with 25 grams of whey protein after exercise failed to stimulate muscle protein synthesis or inhibit protein breakdown to a greater extent than 25 grams of protein alone .
The rise in insulin from protein alone is enough to inhibit the increased rate of muscle protein breakdown that normally happens after training with weights .
In other words, if you’re taking in a reasonable amount of protein after training, the addition of carbohydrate isn’t going to help you gain muscle any faster.
Dig through the research, and you’ll find very little evidence to show that the addition of post-workout carbs to a protein shake has any additional muscle-building benefits compared to the protein shake alone [4, 14].
As far as building muscle is concerned, a post-workout snack could consist of nothing but protein and fat, and you’ll likely see a similar rate of muscle growth had you eaten carbs.
In fact, the combination of fat and protein has a number of interesting benefits in the muscle-building department.
In one study, a post-workout drink containing whole milk was found to be more anabolic than fat-free milk .
Although both drinks led to an increase in protein balance, it was the high fat whole milk that delivered the greatest results.
In another trial, eating whole eggs did a better job of boosting muscle protein synthesis – a key driving force behind muscle repair and growth – than eating the egg white, even when protein intake was identical .
Personally, I like to eat a protein smoothie (protein powder mixed with water, greek yogurt and frozen fruit) after a workout. But that’s not because the carbs are helping me build muscle faster. Rather, it’s just a convenient and tasty way to make sure I get plenty of fruit each day.
How Do Carbs After a Workout Affect Fat Loss?
You may have heard that taking on board fast-acting carbs after a workout will sabotage your attempts to get lean.
The research on the subject is a bit of a mixed bag. Some studies show that taking in carbs after a workout puts the brakes on fat burning, while others show that it has no effect.
One trial, which looked at fat metabolism for three hours after a post-workout meal or plain water, shows little difference in the number of fat calories burned .
A study published in the British Journal of Nutrition shows that fat oxidation remains high even when a large bowl of pasta is eaten after exercise .
On the flip side, Colorado State University researchers found a marked decrease in fat oxidation when a carbohydrate-rich mixed meal was consumed immediately after exercise .
A Canadian team also found that replacing the calories burned during exercise with a post-exercise milk shake limits the normal rise in fat metabolism that occurs after a workout .
However, all four of these studies have limited practical application, and here’s why.
If you really wanted to establish the effect of carbs after a workout on fat loss, you’d need to look at changes in body composition over a period of 2-3 months. Measuring fat metabolism during a narrow window of time immediately after exercise gives you a very limited picture about what’s going on.
To lose body weight, all you need is an energy deficit. As long as a post-workout meal/shake doesn’t reduce or eliminate that deficit, it’s not going to slow your rate of fat loss.
Frequently Asked Questions
What kind of carbs should I eat after a workout?
There’s no rule that says you have to eat carbs of any kind after a workout. Personally, I like to mix frozen berries (which provide around 12-15 grams of carbs) with some whey protein powder and water in a blender, and drink it about 45-60 minutes after my workout is over.
What happens if I don’t eat carbs after a workout?
If you don’t eat carbs after a workout, the only real downside is that muscle glycogen will be resynthesized more slowly. But skipping the post-training carbs won’t make a great deal of difference to the speed at which you gain muscle, and is not as vital as was once believed.
Should I eat carbs or protein after a workout?
If you want to gain (or even just retain) muscle mass, and the rapid replenishment of muscle glycogen isn’t a priority, go with protein. But you don’t have to choose one or the other, and there’s no good reason why you can’t eat both protein and carbs after a workout.
What should you eat after a workout to lose weight?
Eating protein after a workout does have the potential to help you gain (or even just retain) muscle mass while you lose weight, depending on what you ate before the workout, and how much of a gap there is between the end of the workout and your next proper meal.
But what matters most when it comes to weight loss is your nutrient intake over the course of days and weeks, rather than the proximity of those nutrients relative to a workout.
Are carbs better before or after a workout?
You can eat carbs before, after or even during a workout. No single one time is universally better than the other. It all depends on what your goals are, the type of training (i.e. high vs low intensity) you’re doing, and your overall carb intake for the day (i.e. high vs low-carb diet).
For example, let’s say that you want to train first thing in the morning. And let’s also assume that you get shaky and dizzy if you train before eating anything. You’ve tried it for a few weeks, and decided that it’s not for you.
In this case, you’d want your pre-workout meal to contain some protein and carbs, and be relatively light on the stomach. A piece of fruit (such as a banana) and a protein shake (such as whey protein mixed with water) will do the job just fine.
Bananas contain a mixture of starch (a complex carbohydrate) and sugars (sucrose, glucose and fructose), with the exact proportion depending on the degree of ripeness.
Another option would be to have a protein shake minus the banana, then sip on a carb drink (such as Lucozade, Powerade or Gatorade) during the workout itself.
How do you add carbs to your post-workout protein shake?
There are lots of different ways to add carbs to your post-workout protein shake. The way I like to do it is by mixing frozen mixed fruit (blackberries, morello cherries, strawberries, raspberries, blackcurrants and redcurrants) with water and whey protein. I put it into a blender and just mix it all up.
This meal ticks a lot of boxes. It’s got protein, water and fiber, as well as a relatively low energy density. So not only do I get plenty of protein to help my muscles recover and grow, I’m also keeping hunger under control.
The fruit also provides vitamins, minerals and other phytonutrients, which you don’t get from carbohydrate supplements like dextrose or maltodextrin.
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