Audax plus Intermittent fasting trained my body to use fat/ketones effectively.
It's what humans are supposed to do. Burning fat, and metabolising Keytones, is our normal, evolved state, not burning sugars.
It's the last 60 years of cheap, easy-access, Carbs that made us all carb-dependent and "bonked" when the Glycogen burned up after 2 hours (when you still have weeks worth of fat fuel stored).
I've cycled perfectly comfortable after 4 days of zero calories, you just need to make sure you stay in a fat-burning zone. Audax is typically fat-burning cycling.
4 days is impressive!
Is there an easy way based on heart rate to know where the fat burning zone is?
On Saturday I did my first 200k audax. My Wahoo reckons I burned 5200kcal over the 12:54 I was riding. On the day I consumed:
2 cheese & Ham rolls for breakfast.
Glass of orange juice
mars bar
cheese toastie (CP 1)
M&M's ~100gm
Chocolate digestives ~90gm
Chips (portion size unknown)
400ml coke
500ml fanta.
I'm not sure the exact numbers, but I make that something in the 2000-3000kcal range. I did notice towards the end that I was starting to flag a bit (yay for cadence meter), and even stopped with just 1km to go for a handful of M&M's just to give me a kick to get there.
The answer to the question though is, I think, about 2,000kcals. That's why non-cyclists, on the London-Brighton ride, "bonk" about 2-3 hours in. They've been burning glycogen at 600-1000kcals an hour and it's all gone. They aren't adapted to metabolise fat ...so they bonk. They're on empty. A fat-burning cyclist will cycle 50 miles without any difficulty, without the need for carbs. It just needs time to "train" your metabolism. It hurts at first.
Our snacking culture (which shuts off fat-burning immediately) means that we've generally lost our ability to metabolise the very fuel we spent millions of years evolving to use the most efficiently.
How does one go about training one's metabolism? What are the long term side effects of switching to ketotonic energy production?
J
2 cheese & Ham rolls for breakfast.
Glass of orange juice
mars bar
cheese toastie (CP 1)
M&M's ~100gm
Chocolate digestives ~90gm
Chips (portion size unknown)
400ml coke
500ml fanta. Sounds more like you attended a 7 year old's birthday party !!
I'm not medically qualified so take this with a pinch of salt (waits for humorous dietary comment)...but..
Almost everything you consumed was a "quick hit" carb fuel and not optimal for a long steady ride.
M&Ms, Coke, Fanta, Fruit Juice..etc will just spike your blood sugars briefly and then leave you to crash afterwards.
Far better to have a bag of Mixed Nuts, simple carbs, Oatmeal porridge..etc. (There are websites for slowburn endurance carbs).
I've used sweets myself* (Jelly Babies are the accepted "
help me over the final 20km" emergency fuel) but I wouldn't recommend the amount of refined sugar that you ate.
* Nothing works for me like a pint of Bitter Shandy when there's 20-30k to go.
As for the Fat-Burning Zone, I'd use the rule of thumb that, if you can chat away to a fellow cyclist, without getting out of breath, you're probably in Z2 or thereabouts.
As for adapting to burning fat efficiently there's no real shortcuts to actually riding in the zone, without eating. My first year of Audax was a story of eating, bonking & being starving hungry. That improved over time to the point I could do a summer 200 without much more than a bowl of soup.
The long term side effects of a "fasted" lifestyle are positive. It's how we evolved to live. What we do now (Constant Carbs intake) is a very recent change (see: "Type 2 diabetes" and "epidemic").