When I tell people I fast daily while training BJJ five to seven times per week, the response is usually some version of 'you'll lose muscle' or 'that's unsustainable.' I've been doing it for years. My muscle mass is up. My recovery is better than it was in my thirties. My cognitive clarity during training is sharper. And my hormonal profile — testosterone, cortisol, insulin — is measurably improved. This isn't theory. It's my daily reality.
Intermittent fasting — specifically the 16:8 protocol, where eating occurs within an 8-hour window and fasting for 16 hours — has decades of research supporting its benefits for insulin sensitivity, inflammation, autophagy, hormonal regulation, and metabolic flexibility. The muscle-loss concern is a persistent myth that doesn't hold up under scrutiny.
This is the exact protocol I use, why it works physiologically, and how to structure it around high-frequency grappling.
The 16:8 Protocol Explained
I eat between 12pm and 8pm. I train in the morning, fasted or with black coffee. I break the fast post-training with a high-protein meal. The entire structure is built around maximising the anabolic window post-training while preserving the metabolic and hormonal benefits of the fasting period.
- Fast: 8pm to 12pm (16 hours) — including sleep
- Black coffee acceptable during the fast — does not meaningfully break the fast at typical doses
- Training: morning sessions fasted or with coffee 45–60 min pre-training
- Break fast post-training: high-protein meal — beef, eggs, or fish with fat; add carbohydrates after protein and fat
- Second meal: 3–4 hours later within the window
- Final meal: by 8pm — no eating after this regardless of hunger
The Science: What Fasting Actually Does
The metabolic and hormonal effects of 16-hour fasting are well-established. This isn't a diet trend — it's a therapeutic application of one of the oldest human experiences: not eating when food isn't available.
Every meal spikes insulin. Chronic high insulin is the primary driver of metabolic disease, fat accumulation, and hormonal disruption in middle-aged men. The 16-hour fasting window allows insulin to drop fully — improving cellular insulin sensitivity and reducing the baseline that determines how your body partitions nutrients from the next meal.
Autophagy — cellular self-cleaning — is activated by fasting, typically beginning around 12–16 hours into the fast. Damaged proteins, dysfunctional organelles, and cellular debris are recycled. This is the body's primary anti-aging mechanism. You cannot supplement your way to it.
Fasting elevates growth hormone — protecting lean mass and driving fat metabolism. The combination of fasting-induced HGH and training-induced HGH creates a larger daily HGH output than fed training alone, particularly when structured around a morning training window.
Short-term fasting (12–24 hours) increases norepinephrine — raising metabolic rate and preserving resting energy expenditure. The 'fasting slows metabolism' claim applies to prolonged starvation, not daily intermittent fasting.
Longo VD & Mattson MP (2014) — Fasting: Molecular Mechanisms and Clinical Applications. Cell Metabolism.
Fasting and Muscle: The Real Relationship
Muscle catabolism — the breakdown of muscle tissue for energy — requires a prolonged, significant caloric deficit. Skipping breakfast does not constitute starvation. During a 16-hour fast, growth hormone rises, cortisol is managed, and amino acids from the previous day's meals are still cycling through muscle protein synthesis.
- Total daily protein: 1.8–2.2g per kg bodyweight — non-negotiable
- Break fast with protein and fat first — stabilises energy and insulin response
- Carbohydrates around training: within 1–2 hours post-training for glycogen replenishment
- Consistency over perfection: occasional window shifts (8pm dinner, fast until 12pm next day) are fine
The key variable is total daily protein intake within the eating window. If a 90kg grappler consumes 180–200g of animal protein across two to three meals between 12pm and 8pm, hitting the leucine threshold at each meal, muscle protein synthesis is fully supported. The timing of the fast is irrelevant to muscle mass outcomes when protein targets are met.
The question isn't whether you can fast and train. The question is whether you're hitting your protein targets. Get that right and everything else follows.
— Josh Button · @thatjiujiteiroThe Bottom Line
This didn't come from a textbook or a coach handing me a protocol. It came from years of training hard, getting injured, burning out, and rebuilding — smarter every time. Everything in this post is something I do, have done, or have researched deeply enough to stake my performance on.
Start with one thing. Implement it fully. Then add the next. The compounding effect of doing the basics with precision beats any biohack or supplement stack.
Hard to Kill isn't a slogan. It's the standard.
Stay Dangerous. Stay on the Mats. Hard to Kill in Midlife.
