People go keto for many different reasons. Some want to get better at burning fat so they have a clean, reliable source of steady energy at all times. Some people are treating a neurodegenerative disease, or trying to prevent one from occurring in the first place. Others just want to lose body fat, take advantage of the cognitive effects of ketosis , or stop seizures. Those are all common reasons to go keto. Another reason people go keto is for the benefits to physical performance.
Keto increases energy efficiency. You can do more in the aerobic (fat-burning) zone than a sugar-burner.
Keto spares glycogen. The more fat you’re able to utilize, the more glycogen you preserve for truly intense efforts.
Keto builds new mitochondria. Mitochondria are the power plants of our cells. More mitochondria means a larger engine.
That said, the performance benefits take a few weeks to manifest. During this time, a common side effect of the keto transition is reduced performance in the gym. People report feeling sluggish, slow, weak, and flabby in the days and weeks leading up to their adaptation. It’s understandable (and somewhat expected) why this can happen:
Fat provides tons of energy at a slow rate—but you’re not great at accessing it yet.
Glucose is more scarce but provides energy rapidly—and you just took it out of your diet.
Is there anything you can do to improve your performance in the gym during the transition?
Preserving Performance During the Keto Transition
Increase Fat Content
This goes without saying. Of course you’ll be eating more fat on a ketogenic diet. Right? What I mean is you should increase fat even more than you think for the first week. This has the effect of increasing AMPK activity, which hastens the creation of fat-burning mitochondria, upregulates fat metabolism, and speeds up your ability to utilize ketone bodies.
Increase Intake of Specific Fats
Certain fatty acids seem to increase AMPK more than others. The most potent ones I’ve found are:
- Long-chain omega 3 fatty acids , found in fish oil , fatty fish (salmon, mackerel, sardines), and shellfish.
- Extra virgin olive oil rich in polyphenols . The more peppery the oil, the more polyphenols.
- Palmitoleic acid , an omega-7 monounsaturated fat. The best source is mac nuts , unless you’re the type to eat whale blubber.
Include some mac nuts, EVOO, and wild fatty fish (or quality fish oil ) on a regular basis.
Take Your Electrolytes
Electrolytes are already essential when transitioning toward a ketogenic diet. Since they regulate muscle contractions, heart function, intracellular fluid balance, and nerve impulses, they’re even more important when you’re exercising, Try 4.5 grams sodium (about 2 teaspoons of fine salt or a little under 3 teaspoons of kosher salt), 300-400 mg magnesium, and 1-2 grams of potassium each day on top of your normal food. Going keto really flushes out water weight, and tons of electrolytes leave with it.
Stick To Weights and Walking
The big problem with physical performance during the keto transition is that you’re not great at burning fat, you’re still reliant on glucose to fuel your training, and you don’t have much glucose coming in. For the transition window, this makes high intensity, high volume training a bad idea.
Running a race-pace 10k is going to be hard. Participating in the CrossFit Games is a bad idea. You haven’t yet built the machinery necessary to make those work, nor do you have the glucose necessary to tide you over. You know what will work? Weights and walking.
Walking is totally aerobic, using almost no glycogen of note. Weight training can be glycogen-dependent, but doesn’t have to be if you keep weights high and volume low. Think low (2-6 reps) volume weight training. Whatever you do, the key is to make sure your training is low-stress.
Stick to weights and walking and you’ll hasten keto-adaptation, not harm it. Then you can resume some of your normal activities.
Creatine boosts muscle content of phosphocreatine, which we can use to generate large amounts of ATP in a short period of time for quick bursts of speed or strength. This doesn’t dip into glycogen or fat. It’s ATP-PC , or ATP-phosphocreatine. If you’re going to sprint or lift heavy stuff, you’ll definitely want extra creatine in your muscles.
No need to “pre-load” creatine. Just take 5 grams a day and be sure to drink plenty of water and get plenty of electrolytes (which you’ll already be doing on keto).
If you’re going to sprint on keto, keep a few tips in mind.
Short sprints—3-5 seconds.
Plenty of rest—as much as you need to go as hard and fast as the last one. This gives you the chance to replenish some of your phosphocreatine.
This won’t fully replenish your ATP-PC stores. You won’t be able to go as hard, or do as many reps as you’d like in subsequent sprints. But if you absolutely must sprint, this the way to do it without relying on glucose. Look for the sensation of diminished power. That’s when you’re hitting the PC wall and will start dipping into glucose. Avoid that sensation. Stop short of it.
Don’t freak out if you “dip into glucose,” though. Yeah, dipping into glucose constantly will inhibit keto-adaptation in the early stages, but once or twice won’t make a big difference. Just don’t make glucose-intensive work a habit.
Get Primal Endurance
Brad Kearns and I wrote Primal Endurance  because endurance athletes needed a better, safer, healthier way to do the thing they love-hated. I know, because that was us. We both got out of serious endurance athletics because it was harming more than helping us. But that doesn’t mean we stopped missing it. Once an endurance athlete, always an endurance athlete. You can’t shake the bug.
Primal Endurance shows you how to build a powerful, long-lasting aerobic base using primarily stored body fat. It’s the perfect complement to a keto lifestyle, especially if you want to optimize your athletic performance and make your physical activity support rather than inhibit keto-adaptation.
Understand the Purpose of Training
Lifting in the gym isn’t a competition. You’re not being paid. The whole point of lifting weights, running sprints, and doing low level aerobic activity is to get better at doing those things. It’s not about “winning” every workout. That’s what training is—accepting paltry results with the assurance that you’re getting better. Think about it.
When you add 50 pounds to the bar, it’s harder. The bar moves more slowly. You can’t do as many reps. From your brain’s perspective, you’re suddenly “weaker.” Yet, it’s the best way to get stronger in the long run.
When you try a new sport or physical activity, you’re no good. You’re a beginner. People you’re sure you could trounce in your preferred activities are destroying you. This doesn’t mean you should give up. It means you have to get better. And if you stick with it, you will get better.
When you train on your newly keto diet, think of it like you’re increasing weight, upping the intensity, or learning a new sport. You’re not weaker. You’re not getting worse. The training is getting harder. The pain is increasing. And, although it might not feel like it right now, you’re going to be better off in the long run.
Once you’re fully fat-adapted and able to utilize fats, ketones, and glycogen, you’re going to be an unstoppable force.
Okay, that’s short term. What about long term?
How To Enhance Performance Long-Term With Keto
Carb Cycle When Necessary
Once you’ve been keto for at least a month, don’t be afraid to cycle in carbs to support your intense training. If you’ve depleted muscle glycogen with an intense training session, you’ve created a glycogen debt and any carbs you eat in the hours following that workout will go to repleting that glycogen. Best of all, intense training upregulates insulin-independent glycogen uptake  immediately post-workout. That means if you do it right, you don’t even need to increase insulin to shove those glucose molecules into your muscles.
Carb Cycle the Right Way
Many people do carb cycling on keto completely wrong. They spend two days binging on bear claws and gummy bears then wonder why they’ve gained weight and lost progress. A few tips:
You probably need fewer carbs than you think. A little snack of 20-40 grams of carbs right after a really intense workout can make all the difference in the world without knocking you out of ketosis, provided you’ve accumulated enough of a glycogen debt.
Choose the right carbs. A sweet potato the night before to top off glycogen stores, a cooked-and-cooled white potato (diced and quickly seared until crispy in a pan is my favorite way to eat these), or UCAN Superstarch (whose slow absorption has minimal impact on insulin and thus ketones) are all good choices.
Do it for the right reasons. Don’t carb cycle because you miss French fries. Carb cycle because you’ve depleted glycogen.
And hell, briefly exiting ketosis isn’t the end of the world. Most people doing keto aren’t doing it as a life or death intervention. They just want to look, feel, and perform better. Don’t let keto become an ideology. It is a tool for your pleasure.
Chase Results, Not Ketones
In my experience, the people who focus on results rather than ketone readings do best.
Heck, if you spend half your time stressing about your ketone levels, the resultant cortisol will probably trigger gluconeogenesis and inhibit keto-adaptation by introducing a flood of new glucose into your body.
Are you leaning out? Thinking more clearly? Skipping the afternoon nap and breakroom donuts without even thinking about it? Lifting more? Running easier? Lab tests improving?
Then you’re good. That’s what matters.
Besides, the point of keto-adaptation is fat-adaptation—the ability of your muscles to utilize free fatty acids. That’s the real power of going keto, because once the fat-burning machinery is established and your muscles can use fats directly, you have more leeway to eat protein and cycle carbs.
Those are the tips I’ve found to be most useful for people acclimating to exercise on a keto diet. What’s worked for you?