Can Carbs and Ketosis Coexist in High-Intensity Training?

Since starting my ketogenic journey on September 18, I've consistently maintained ketosis, confirmed by daily finger-prick testing. Along the way, I've encountered the expected challenges—especially, a heavy, sluggish feeling in my legs during uphill runs and a lack of explosiveness in intense workouts.

Rather than rushing to tweak my nutrition, I gave my body time to fully transition to fat-burning mode. Now, with a solid foundation in place, I'm beginning a deliberate experiment: targeted carb intake during exercise.

Why Experiment with Carbs on Keto?

While fat adaptation offers remarkable benefits—consistent energy, better sleep, weight loss, and improved insulin sensitivity—it has a downside: reduced explosive power during high-intensity exercise. Carbohydrates remain the body's preferred fuel source for these intense efforts.

I recently heard David Roche—a renowned endurance coach and athlete—share his carb intake on the Some Work, All Play podcast: Up to 150 grams per hour—a stark contrast to my 0 grams! Around the same time, KoopCast showed up in my feed.  In this podcast, Jason Koop and his guest discussed a study on carb intake during competition. Athletes consumed 60, 90, or 120 grams per hour, with the 120-gram group achieving slightly better performance and significantly better recovery.

This is a big deal. Improved recovery means less muscle damage, faster progress, and higher levels of performance.

First Test: Gu and Ninja

This weekend, I tore open a Gu and thought, "Let's see what happens." My local ninja obstacle-course gym served as a fitting testing ground, as these workouts take both strength and endurance.

Before the workout, I consumed a single gel, delivering 22g of carbs—a significant portion of my daily carb budget (25-30g on keto). For keto purists, this would blow past the 20g limit for the entire day. However, the theory is simple: during intense workouts, your body rapidly burns through those carbs, allowing you to return to ketosis soon afterward.

Ninja Training (Saturday)

• Protocol: 22g carbs
• Duration: 1 hr
• Pre: Ketones 0.5, BG 111
• Post: Ketones 0.5, BG 121
• 1hr Post: Ketones 0.5, BG 116
• 2hr Post: 0.8, BG 93

This experiment wasn't about nailing the perfect carb amount—it was about testing whether one little gel could supercharge my workout without kicking me out of ketosis. The results were encouraging: I stayed in ketosis, and I felt stronger! Next up: testing this approach with different workouts.

A Week of Workouts

Building on my initial success, I tested carb intake across a variety of workouts throughout the week:

Speed Intervals (Monday)

• Protocol: 22g carbs at start
• Duration: 32 min (1-min on, 1-min off)
• Pre: Ketones 0.9, BG 83
• Post: Ketones 0.4, BG 144
• 1hr Post: Ketones 0.7, BG 91

Ninja Training (Wednesday)

• Protocol: 2x22g carbs, 40min apart
• Duration: 1 hr
• Pre: Ketones 0.6, BG 103
• Post: Ketones 0.2, BG 146
• 1hr Post: Ketones 0.4, BG 103
• 2hr Post: 0.6, BG 105

Tempo Run (Thursday)

• Protocol: 2x22g carbs, 30min apart
• Duration: 40 min (10-min warmup, 20-min tempo, 10-min cooldown)
• Pre: Ketones 0.8, BG 101
• Post: Ketones 0.4, BG 179
• 1hr Post: Ketones 0.6, BG 110

Zone 2 Run (Friday)

• Protocol: 22g carbs every 20min (88g total)
• Duration: 80 min
• Pre: Ketones 0.8, BG 80
• Post: Ketones 0.5, BG 183
• 1hr Post-run: Ketones 0.8, BG 99

Each time, my ketones recovered within an hour or two, and my blood glucose (BG) returned to reasonable levels. And with today's experiment, it's clear I haven't hit the ceiling yet.

What I've Learned (And Where I'm Headed)

These experiments are just the beginning. Two key effects I'm aiming to optimize are:

1. Performance: The energy boost from carbs is undeniable. For example, on both the first day of keto (9/18) and the first day I took the Gu (11/9), I scaled the 14.5-foot warped wall-—something I couldn't manage during the weeks in between.
2. Recovery: By fueling my body during exercise, I believe I am reducing muscle damage, potentially lowering the risk of injury and boosting long-term performance.

My goal is to strike the right balance between carb intake and maintaining ketosis. I'm not aiming for surgical precision—just a sweet spot that maximizes my performance within the bounds of ketosis.