Morning Exercise, Hypoglycemia, And Intermittent Fasting

Hello. I just bought the Bulletproof diet book and am seriously considering making this my lifestyle, including 18 hours of intermittent fasting every day. However, I see a potential problem. When I was on the Whole 30, with pretty much no carbs, I found that I was totally 'bonking' (running out of steam) on my morning 10-20 mile, strenuous bike ride. Seemed like once I blew out my glycemic stores, I often had a total energy crash. I have a tendency towards hypoglycemia anyway (and there is diabetes in my family), and so I amended the diet to include some carbs ('Clif Blocks') while I was riding, to keep me going.


I assume that the same thing will happen here. I don't think this necessarily happens to all people, I can't say, but it appears to, consistently, for me: I just run out of steam, and once I pass that point, it's cold sweat, brain fog, dizziness. it sucks.


I am sure primitive man could do lots of exercise with no carbs. He must have been able to. But he also wasn't overweight and he didn't have metabolic syndrome/Insulin Insensitivity, which I'm sure I do have. 


So, how best to cope with this on the bulletproof diet?





  • First off, if you're exercising every day, you'll need to adjust carbs on the BP diet. The BP diet is optimized for mental performance, and perhaps one workout a week. Using the same macros while doing strenuous exercise every morning is a recipe for disaster. There is a sticky'd post in the Athletic Performance forum on how to adjust BP macros for exercise. 


    If you want to continue morning bike rides, you could shift your IF eating window and if we said standard IF was "skipping breakfast" then you'd be skipping dinner. 


    If you made your morning rides not strenuous... say no more than 60% of max effort, you could probably run that on fat. But if you're sprinting up hills, you're burning through glycogen, and you'll need to replace it. 


    As for primitive man doing plenty of exercise on low carb, I'm not so sure. You can hike slowly all day on fat, and so it's possible primitive people only used carbs for the occasional sprint at prey or away from a predator. Also there's plenty of evidence we were cooking starchy tubers for the majority of human evolution. 

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