Carbs Before a Workout on Keto: How to Dose Them for Hard Training
Three and a half minutes on one narrow question: if you train hard, should you eat carbs around your workouts while doing keto? My answer was that most people watching didn't need to, and that the people who did should treat it as an experiment in practice, never something new on competition day.
In this video
- [0:00] On keto you may not have the same explosive energy for some workouts. The first question is whether that matters for you.
- [0:30] If you're doing keto for weight loss, like most people, you probably don't need workout carbs. CrossFit competition or high-intensity interval training is where it starts to matter.
- [1:00] Slow carbs (heavy starches, crackers) go in the one-to-two-hour window before. Fast carbs (a sports drink, honey) can go about 30 minutes before. Experiment in training so you know what to expect.
- [2:00] Walking, jogging, an elliptical or light resistance training don't need carbs. I'd done an hour-plus of kickboxing on keto without them and kept my energy up.
- [2:30] The cases where I'd experiment: wrestlers, track athletes, a sports camp, basketball several times a week, very heavy lifting, or lifting combined with intervals.
- [3:00] After a workout, the window I gave was 30 to 90 minutes, up to two hours. Amounts: 10 to 20 g before and 10 to 20 g after, starting near 10 each.
Then vs now: the numbers got smaller
Three weeks before this, in a live video on exercise, I gave weekend competitors a bigger dose: 20 to 50 g of carbs two hours before and about 20 g after (video f119qGyJ7AY). In this video the range dropped to 10 to 20 g on each side, with "keep your carbs minimal" as the instruction (video XhEJ9x5sP0g).
I didn't explain the change in either video. Reading them side by side, the later one is the more careful version: start at the smallest dose that might help and only go up if you actually feel a difference. If you watch both, use the smaller numbers as your starting point.
The line that holds up: first ask whether it matters
The best sentence in this video is the first real one. Before you work out how to dose carbs, ask whether a bit less punch at the end of a workout even matters to you.
For someone exercising to feel better and support weight loss, feeling a little flat at the end of a session isn't a problem to fix. I said the same about myself in my first long Q&A: in MMA class I'd gas out sooner on keto, and I treated it as practice for fighting tired. I also said that in a real fight camp I'd probably put some carbs back (video cTGYIFOTPl8).
That's still the right order. Decide what the workout is for, then decide whether carbs serve it.
What the evidence pages cover, and what they don't
None of the evidence pages has a study on carb timing or dosing around exercise on a ketogenic diet. In the video I said the 30-to-90-minute recovery window is what's usually discussed in the muscle literature. That's my summary from 2017, and the pages here don't check it, so read the windows and gram amounts as a starting experiment, not a protocol.
What the pages do cover is protein, which matters more for most people training on keto than a few grams of carbs. The International Society of Sports Nutrition puts most exercising people at 1.4 to 2.0 g of protein per kg of body weight per day, in doses of 20 to 40 g every three to four hours (ISSN 2017). A pooled analysis of 49 trials found protein supplementation added to resistance-training gains in fat-free mass and strength, with the benefit levelling off around 1.6 g/kg/day (Morton 2018).
If your workouts feel flat, it's worth checking you're actually eating your protein before you start adding carbs.
If you take diabetes medication
Exercise lowers blood sugar, and so does cutting carbs. If you're on insulin or another medication that lowers glucose, adding or removing carbs around workouts changes your risk of going low. That's a plan to make with your doctor, not by copying the gram amounts here.
Key points
- Most people doing keto for weight loss don't need workout carbs.
- Explosive, fully anaerobic training (sprints, wrestling, competitive CrossFit, very heavy lifting) is where an experiment makes sense.
- Slow carbs one to two hours before, fast carbs about 30 minutes before, some after.
- Start small: about 10 g before and 10 g after, up to 20 each if you feel a real benefit.
- Test it in training, never for the first time on competition day.
- Check your protein before you add carbs.