Targeted Ketogenic Diet / Carb Intake
When you stop eating carbs and go on a ketogenic diet, it’s likely that your high-intensity exercise performance will go down (Haff et al. 2001). So, you may benefit from ingesting carbs before, during, or right after your workouts to bring your performance back up. This is sometimes called a “targeted ketogenic diet.”
It seems the term was coined by Lyle McDonald in 1998: “The Targeted Ketogenic Diet is nothing more than the standard ketogenic diet with carbohydrates consumed at specific times around exercise.”
I’m aware of only one peer reviewed study (a case study) supporting that practice. In that study, Webster et al. (2018) found that:
“CHO ingestion during exercise was likely beneficial for this fat-adapted athlete during high-intensity endurance-type exercise (4-30 min) but likely did not benefit his short-sprint or prolonged endurance performance.”
As part of the protocol, the triathlete ingested 60 g of carbs per hour of training (endurance-type exercise). If you lift weights, your optimal intake is most likely lower.
How low? Keto expert Luis Villaseñor (2015) recommends taking 5-15 g of carbs before you work out. In a personal communication, Villañenor (2019) commented:
“Its my go to personal approach. But I do require little carbs (~10 to 15g pre). Just use 5g for under 70k people and start adding ~5g depending on duration of training and size of the person. I’ve never had people use more than ~20g post and maybe extra ~10g peri [around your workout]”
Anecdotally, other athletes report a boost in performance. In an informal survey, I asked “Anyone used it and seen a boost in performance?” One athlete said:
“I was able to sustain […] efforts for longer and no longer felt energy depleted afterwards.”
“Definite performance lift” for “longer + high intensity sessions (i.e. 2 hrs kickboxing)”.
This is anecdotal evidence. Still, it supports the idea that you may benefit from ingesting carbs around your workouts.
Targeted Ketogenic Diet Guidelines
Based on the above, if you’re on a keto diet and you’d like to try a targeted carb intake, I propose the following guidelines:
- If you run, bike, or do endurance-type exercise, ingest 60 g of carbs per hour of training (starting from the beginning of your workout).
- If you lift weights, ingest 10 g before and 10-15 g after your workout.