Im going full keto 800 calorie so thats probably the last race i will manage to compete in for the next month!
Once you've become fat adapted metabolically, there is no reason to not race, you don't need carbs to do high intensity activities.. the body makes sufficient glucose through gluconeogenesis as long you are consuming enough lipid/protein calories per day.
Is it diabetic reason?
Is that 800 cals reduction or total 800 cals consumed per day? 800 per day total consumed is proper hard core, entering starvation mode, which is not recommended.
All the best with it