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Comment by juskrey | Hacker News Reader

After years of struggling with eating during endurance sports, I have finally discovered the best approach: No food right before sports, no food during sports. Ended up proving my point (mostly to myself) by doing half-Ironman on plain water. Never eating on cycle or run again. Pure, pure evil.

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This is a difficult thing to just say "I do this and here is what I did". People's body's can be very different. For example, pro cyclists burn fat and carbs differently than normal people do to years of conditioning( aka base miles). That high fat diet only works for super intense athletes. Try and let me know how your cholesterol levels end up. Haha

Food prior to very long endurance Activites is good to stop the gastrointestinal events during the event. So I do agree with the benefits there however gels unlike solid food better absorb and replenish carbohydrate stores so you can maintain higher/intense efforts for longer. Otherwise you could "bonk". But yeah... It all depends on the activity, duration, intensity , pre-training and food consption etc...

I race/ride bikes as well. So 250-300mi or 15hr each week on the bike( more if I didn't have a day job).

I got my family's high LDL and cholesterol, which normalized for the 2 years I was on keto and stayed low after.

I went from having my GP threatening to put me on Crestor to asking for blood work every month for a while to accepting it was working and probably not going to be the death of me. Apparently dietary cholesterol doesn't really affect blood level.

I'm not an athlete, but I do about 10 miles a day. Nothing special.

10 miles a day? running? you do realize that's like way outside the mean right?

I believe the thread is regarding cycling.

When I was swimming competitively, we'd always eat enormous amounts of spaghetti the evening before and then eat virtually nothing except maybe a fruit or few pieces of candy the morning of the meet.

(As far as I know it's a total nonsense myth that eating food before swimming is dangerous. We frequently at large meals before practice and nobody ever cramped up and drowned. But from a performance standpoint in a race, having an empty stomach seemed beneficial.)

If you go hard enough for long enough, you'll run out of glycogen. If you're not maintaining your blood glucose levels by ingesting carbohydrate, you'll go hypoglycaemic and turn into a wobbly mess of useless limbs.

https://www.youtube.com/watch?v=liCRrheKIOI

Finishing a 70.3 on plain water is just about feasible if you're not particularly fast, but a reasonably quick amateur is going to end up bonking in spectacular fashion, let alone an elite athlete.

You can’t really bonk if you’re adapted to and in ketosis. Using only carbs for athletic performance is like having a hybrid car but disconnecting your gas tank.

While training for that, bonk was my second name. Nothing morbid, nothing human can't cope with. I was not saying anyone can stand up from the bed and go long.

Yet all that carb horrors are lies.

The last athlete I worked with pointed out that you can only absorb about 800 cal an hour but burn way more than that, so you simply can’t eat fast enough to avoid losing weight during an even like this, but you’re talking about burning an extra pound off by not eating at all during events.

What’s your bodily complaint that makes this difficult?

The last time I tried not eating on an endurance bike ride, I felt horrible and started shaking by the end of it. I suspect my glycogen levels got out of whack after about 5 hours of vigorous riding with no replenishment. Every body is different, and some need (and I guess tolerate) eating in the middle of the activity.

Adaption and experience turns that sharp cliff of bonking into a gentle slope, but you're going down eventually nonetheless. Five hours matches my experience as well and is also roughly the duration of a half-ironman.

But you can do both. Water for everything up to a longer (but not the longest) Sunday ride, carbs for multi-day (you won't replenish glycogen in one night), for true all day riding and for the occasional short all out competition.

What you can't do is run on water all the time, then suddenly add carbs and expect it to work out well: when I started venturing beyond my "water only horizon" (which was more like three hours at the time) it felt very much as if the body would shut down all other energy paths once carbs were available and won't be able to restore them once the carbs run out and then you need to refuel as fast as a carbs-only athlete and that's just impossible for someone used to water.

Now I think that a more accurate model is that when carbs become available, an athlete not used to that will increase energy throughput by more than what the extra carbs can supply and exhaust the other sources during the sugar high. After that it is impossible to apply carbs fast enough to compensate. But avoiding overexertion during the sugar high is easy to learn and then you are an energy generalist, going for hours when water will be enough and adding some carbs on those special occasions.

I dunno about "evil," but yeah - you probably won't die of lack of calories during an event like that. There's this whole "fat adapted athlete" thing going on in the ultra-marathon world that kinda proves the theory....

I've only done one "endurance" event, a 40 mile bike through hills. I did the whole "don't eat much" and then skimped on my break and goop in the last ten miles. I made it, but I crashed hard, metaphorically.

How do you prep beforehand?

Carb load the night before, light breakfast, and energy bars/good/etc during. Usually doing 60-100 mile (5-10 hour) rides.

Being fit is enough for such an event (no prep or food needed). But if you're not fit then you need to intake carbohydrates as you go.

At that time I was in deep keto with lots of training on water also. Now I am on paleo (with eventual natural carbs and not watching my ketone blood levels anymore) and intermittent fasting - the effect is even better. (After lots of experiments on myself I have realized that deep keto mode is naturally for prolonged fasting, so enforcing it with fats intake is a perversion)

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