Keto for Athletes: When to Add Carbs Around a Hard Workout (3-Minute Answer, 2017)

2017-07-17

In this recording

A three-minute clip from July 2017, answering one question: what about keto for athletes? It sat in a "to be reviewed" folder and was never posted to YouTube.

[0:00] First, define "athlete". A walk with a friend, light weights, a workout DVD or gentle yoga needs no change to keto. The question sounded like it came from someone doing CrossFit hard.
[0:27] What are your goals? If you run out of gas at CrossFit and you're there for weight loss, that may not matter. If you want to compete and perform at your best, ketosis alone probably won't fuel high-output work.
[1:01] What I'd been reading: people take carbs about two hours before, during, or right after training. That might be a pre-workout, a recovery shake, or a sports drink mid-session.
[1:29] Why it works: if you've just trained, are training, or will within a few hours, your body uses that glucose before it gets stored as glycogen. So I suggested you could probably fit something like 20 extra carbs around a workout.
[2:02] My own case: I was training MMA with a much younger fighter. We sparred, and I let myself get tired on purpose. Training isn't a competition for me, so not being at my best was fine.
[2:34] "Optimal" here means performance, not health. Gassing out is fine if weight loss is the goal. For recovery, take carbs after. For performance, I'd go about two hours before.

Watching this in 2026

This is one of my early answers to this question. I still agree with the first move: ask what you're training for before you change anything. Most people asking "keto and exercise" walk, lift a little, or take a class a few times a week. They don't need a carb protocol. They need to stop worrying that being a bit flat in a hard class means keto is failing them.

What I'd add now is that I was passing on what I had been reading, not something I had tested as a protocol. I said "what I've been reading" and I meant it. I didn't name a study, and none of the evidence pages I use now covers carb timing around workouts. So treat the numbers here as a starting point to try in training, not a rule.

Then vs now

A cleaner, pre-recorded version went up on 2017-08-24 (video XhEJ9x5sP0g). By then the advice had more detail: slower carbs one to two hours before, faster carbs about 30 minutes before, some after for recovery, and small amounts, roughly 10–20 g before and 10–20 g after. Here it's a single "about 20 extra" around the workout. The core is the same: the carbs go in when your muscles will use them right away.

In a longer Live with the same file date, I made the same point about competitive athletes and the two-hours-before, during or after timing, and added that if weight loss is the goal, diet comes before exercise (live 10000000_637424646467238_6646023133880909824_n).

When to talk to a doctor

If you take insulin or other glucose-lowering medication, adding carbs around training, or training hard while low carb, changes your blood sugar in ways your doctor should plan with you. That's not something to work out from a three-minute answer.

Key points

Everyday exercise (walking, light lifting, yoga, classes) needs no change to keto.
For high-output training where performance matters, a small dose of carbs timed around the session can help.
Carbs taken just before, during or after training tend to get used rather than stored.
If weight loss is the goal, running out of gas in a hard class is fine.
These timings came from my reading and my own training, not from a cited study.