SethAZ 

Ok, well that actually does sound like a true bonk. Btw, that's a serious thing, and you really need to have some calories available for something like that, because raising the blood sugar level is what's needed, not willpower.

All I can say is that losing weight through hard, long distance cycling is a balancing act, and one which I personally am still tinkering with. The challenge is that if you're riding hard enough, and far enough, then your body probably can't keep up with the rate of calories burned by metabolizing your body fat, but if you're going low calorie, low carb diet then it's really easy to be at too low of an energy state. If your glycogen stores aren't topped off then you probably don't have the 90 minutes' worth people popularly write about.

What I do personally, and I'm still working on this and am not claiming to be an expert on it, is for my longer rides I make sure I've at least got some gatorade powder mixed in in my second water bottle. I'll go with the water-only bottle to begin with, and hold back going with the gatorade if I'm doing fine, but I'll start drinking it without hesitation if I get any inkling that my energy state is low enough that my fat metabolism isn't keeping up. I have one of those little snack bags that attaches to my bike right behind the stem, and I'll typically have an energy goo, or a calorie bar of some sort like a Cliff bar or whatever in that little bag. I don't eat it, it just sits there as an emergency reserve. If my gatorade bottle isn't sufficient and I'm in real calorie trouble I want to have those calories available as an emergency measure.

It's really easy to get into this mind trap where you're hesitant to eat or drink any calories because you're trying to lose weight and you think it just takes will power to gut it out, but bonking for real isn't about willpower. It's about whether your brain is going to starve because your body, even burning fat, is just incapable of keeping up with the calorie demand. Hence the fallback plan of having calories available. Additionally, I carry my wallet with me in my jersey pocket, and I plan all my rides that are longer than 25 or 32 miles so that on the back half of the ride I'm never further than maybe 2 or 3 miles from a gas station. I live in a part of AZ where I ride on tons of back roads and rural roads and whatnot, but I live right on the edge of where the citification keeps pushing out into the desert, and it's not hard to ride roads where there's a Circle K or some other gas station not that far away. If I'm feeling in calorie trouble I do not hesitate to stop there, get a sugary coffee and sometimes an additional snack, take 7 to 10 minutes to rest up and drink the calories, then continue on.

I'm at the point where I have a pretty good idea of what my fat-burning metabolism can handle, and I plan accordingly. I know I can do a 25 mile route pretty easily on an empty stomach. I can typically do my 32-mile route on an empty stomach if I don't push my heart rate past the zone 2/zone 3 boundary. Any further than 32 miles is stepping closer to the brink than I like, and hence the gatorade/emergency calorie/gas station treat options. A month ago I did a 50 mile ride during a week of tons of other miles, where I decided to see how far I got on an empty stomach. It wasn't truly empty because I'd eaten a little two or three hours before the ride, so it wasn't quite the same as an early morning "fasted state" ride. I ended up stopping at a 7-11 at around the 43 mile mark and getting a sugary coffee and snack. I hadn't bonked, but I detected signs of stress that tripped the Master Caution light in my mind, and I didn't hesitate. These signs of stress included that my heart rate was going up 5-10 bpm with no increase, and even perhaps a slight decrease in how fast I was riding. After a 7-10 minute break and some iced sweet coffee at the 7-11 I rode home the last 7 miles and was fine.

My current training regimen includes early morning "fasted state" bike rides, on water and black coffee only. I have a target heart rate which I've determined after reading a few online articles about cardio base training and improving the efficiency of burning body fat. If I'm feeling really good and look down and find out I'm 5-10 bpm higher than this target, I'll slow down. If I look down and I'm 5-10 bpm lower than this heart rate, I'll speed up. This heart rate wasn't determined for me by some sort of scientific testing or anything like that, so it's really just a SWAG, but the idea is that at this heart rate I have the best chance of improving my cardio endurance while also training my body to be more efficient at burning my extensive internal lipid stores.

Doing like a 12-15 mile ride this way I don't even bring the Gatorade backup, but doing my 32-mile route I definitely do. I often don't drink it, but if I feel any signs of energy stress I don't hesitate at all.

Anyhow, I'm glad that nothing really bad came from your experience. I know you didn't ask for any advice, but as I'm basically still a fat body, and also an aspiring long distance cyclist, and have been tinkering with diet, cycling for calorie burn and long distance endurance, etc. I thought I'd share my thoughts on it.

Bottom line is this: low energy state is no joke when you're out on a bike. You should have an energy plan, and that includes a backup plan where you have some calories you can eat/drink for a near-instant energy state raise, because bonking doesn't mean you're losing the most weight; it means your brain is fighting hard to keep itself from dying. Dain bramage isn't worth it. Bring some calories.