A widely held belief is that we absolutely need carbohydrates for successful workout recovery. The reasoning behind this is that carbohydrates help replenish glycogen. They also spike insulin which supports muscle protein synthesis. If that is the case, does that mean that low carb diets like the keto diet are detrimental to workout success?

Why carbohydrates are recommended?

After a tough workout, your glycogen stores become depleted. In case you are not familiar: glycogen is carbohydrate stored in muscle tissue. It fuels much of your workouts.

Traditional sports nutrition advice says we need to replenish that lost glycogen as soon as possible. Failing to do so is bound to slow down your recovery.

More specifically, taking carbohydrates within a couple of hours after vigorous training is believed to:

• Replenish muscle glycogen
• Spike insulin which is an important anabolic hormone
• Increase water content within muscle tissue
• Lower levels of cortisol, a catabolic hormone

However, many of these claims are now being questioned. And some are really not all important for the average person.

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If you’re someone who works out three times a week, for example, there’s no need for you to speed up the rate at which your muscle glycogen gets replenished. As long as you’re eating some carbohydrates, your glycogen stores will get back to normal within two days.

Besides that, studies have found that protein, especially the amino acid leucine, spike insulin just as much as carbohydrates. Studies also found that taking carbs together with protein was no more effective than a placebo when it comes to workout recovery.

The keto diet and workout recovery

The ketogenic (keto) diet is controversial in regard to sports nutrition. Because carbs are considered essential for performance and post-workout recovery, a diet deficient in carbs seems like a recipe for disaster. But the human body is complex and able to adapt to things we think impossible.

So, what does the science say about keto diets
and workout recovery?

Dr. Jeff Volek, a renowned low-carb researcher led a study that was published in a 2016 issue of Metabolism. The study revealed that 10 ultra-endurance athletes who had been following a keto diet for at least 6 months showed a higher fat oxidation rate and a lower carbohydrate oxidation rate during exercise. They also showed similar muscle glycogen levels at rest as the control group.

The study also found that glycogen levels recovered at the same rate in the keto group as well as the control group. This was despite the fact that the keto group consumed a diet containing 5% carbohydrates while the control group diet had 50% carbohydrates.

This study concluded that endurance athletes could maintain normal muscle glycogen content, utilization, and recovery after long-term adaptation to a ketogenic diet.

This study shows that adapting to a low-carb diet like keto makes the body use fat for energy during workouts while sparing muscle glycogen. With less glycogen lost, you need fewer carbs to recover. However, it takes several months to truly adapt to low-carb diets, so performance and recovery may suffer in the meantime. This has been confirmed by short-term studies.

Another thing to keep in mind is that ketosis, which is the primary goal of the ketogenic diet, is not the end goal of this diet. Instead, it is keto-adaptation (after long-term ketosis) that matters, especially for athletic types. 

Some limitations of the keto diet

There is a caveat to using keto for workouts. Researchers agree that workouts that heavily rely on anaerobic metabolisms, like strength training, will not work on a fat-fueled diet. That’s because ketones and fat cannot be metabolized anaerobically.

But this may apply only to athletes. Common folk may actually do quite well on a low-carb diet where strength training and other anaerobic-heavy workouts are concerned.

A study published in Nutrition & Metabolism found that the keto diet combined with resistance training reduces body fat without affecting muscle mass in untrained overweight women. So, there was no major impairment.

Central Fatigue

Another problem with the keto diet when it comes to workout recovery is how it affects central fatigue, meaning feelings of tiredness caused by changes in brain chemicals.

There’s evidence that when you’re burning more fat, the brain takes up more tryptophan – a precursor to the production of the feel-good neurotransmitter serotonin, which makes you feel tired.

Eating too much protein on this diet, which isn’t uncommon in people who regularly exercise, can also lead to elevated ammonia production during workouts. Ammonia alters energy metabolism in the brain and also communication between nerve cells, all of which leads to feelings of fatigue.

However, most of this evidence is based on short-term research, and longer studies on keto-adapted subjects are needed to check if keto truly does make you feel tired after workouts.

What else you need to consider

A major benefit of the keto diet is that it enhances fat burning. Most people follow this diet for this very reason. Even athletes may use it to shed pounds before major events.

What’s best about keto is that it is proven to burn fat while sparing muscle – something not found with most other weight-loss programs. The keto diet also does not affect resting metabolic rate (RMR) even after it leads to major weight loss.

And while you can definitely use this diet to burn fat, there are things you need to consider if you’re someone who’s an athlete or very active:

1. Increasing sodium intake

Another pioneering expert in keto sports nutrition, Dr. Stephen Phinney, recommends consuming more sodium on a keto diet. Between 3,000 and 5,000 mg of this important electrolyte is necessary to maintain normal metabolism and hydration levels, especially if you’re athletic. Besides sodium, Dr. Phinney recommends consuming 3,000 to 4,000 mg of potassium and 300-500mg of magnesium.

2. Carb cycling

The cyclical ketogenic diet (CKD) involves cycling between the standard keto diet and a high-carb diet. Usually, dieters will eat low-carb for 5-6 days of the week and do a carb refeed on days 6 and/or 7.

On carb-refeed days, you will be temporarily kicked out of ketosis. This helps restore muscle glycogen to greater levels than you could achieve by maintaining ketosis. This approach seems to work better for athletes than standard keto.

3. Targeting carb intake

Another option is to target your carbohydrate intake around your workouts. This is called the targeted ketogenic (TKD). This nutritional approach was developed to help athletic types fuel their workouts and improve post-exercise recovery.

If you’re someone who takes part in vigorous anaerobic activity, this method may be best for you.

Conclusion

Post-workout recovery is an essential aspect of all types of training. Resting is one part of the process, proper nutrition is another.

Usually, you will hear that carbohydrates are essential for proper workout recovery. And, that low-carb diets like keto cannot help with this process. However, this is simply not true.

The keto diet does not impair post-workout recovery in most cases. But it isn’t perfect, and whether you should consider it for your exercise regime boils down to personal choice. The reason? We don’t know everything about sports nutrition.   

So the question of whether carbs are necessary for
workout recovery or if ketones can suffice remains open.

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