Jfitalia

why do you want to limit your protein as well? I you really should be taking in on average .5gram per lb you weigh. How much of your dailey carb intake are you trying to get rid of?

Carbonfiberboy 

I've been rather intrigued by recent low carb cycling threads. I like nothing better than experimenting on myself, so that's what I did. Recent history: This season I've really tried to periodize it, doing more than my usual LSD early in the season, getting in good miles, following Thomas Chapple's Base Training for Cyclists, which emphasizes increasing the percentage of energy derived from fat. Then we've been ramping it up with some competitive group rides the last few weeks. I ride tandem with my wife, and she's made a lot of progress this spring. We've been climbing in reasonable proximity to some fairly strong singles. Last Sunday's ride was really good: hung with some stronger riders, got about 1.5 hours of SST in one ride - my LT is about 151, so a lot of 142-148 type of thing.

We started a reduced carb regimen after that successful Sunday ride and stuck with it all week. We dropped about 2 lbs. a piece, which does not seem unusual for low-carbers.

This Sunday's (today's) ride was our first pass climbing ride of the season. On the first pass, my legs hurt like the devil, I couldn't raise a HR of over 138, we were stuck in little gears, and I was very irritable. During and after our 25 mile descent, I started hitting the carbs hard, doing a little over 300 calories/hour. By the time we got near the top of the second pass, my leg pain had mostly gone away, I felt decent, and my HR was up to 142, still crappy, but a lot better, and we were climbing a cog higher in spite of having 5000' in our legs. And all we'd done all week was 35 miles on Thursday at a pretty good pace with normal HR response.

My conclusion? Stupid, stupid, stupid, CFB. Very low glycogen. I should have carbo loaded the last 2 days before the ride. We did have pasta for dinner the night before, but much too little, too late. Low carbs: no problemo if one is not going to ride hard, but contraindicated for any serious riding. I never recovered from Thursday.

bored117 

I think there is a little confusion running around between Low carb and Atkins here. You DON'T want to go into Ketosis for cycling IMHO. Also, your body at least takes 2-3 weeks to adjust. Thing about Ketosis is.. It really stresses your Liver. Which probably is very counter effective for your recovery, etc. Of course, Ketosis will burn more fat/reduce weight faster than just about any method I know of... (I've done Atkins diet for about 6 months prior to cycling... works great for inactive people) but I can't recommend it for long term with the stress it puts on your body.
What I believe lot of people mean by low carb is more in line of low/none of highly refined carb in your diet. Which actually works quiet well in cutting down the carb as it is much harder to eat lot of low GI carbs (it just is too filling to eat much). Also, these are typically things that have great set of micro nutrients which builds up our body.
I put a little twist on it by eating carbs while riding so my fat burning engine can be fueled as well. (We will always burn both... just different ratio) Seems to work good for me. But than, I don't race. I might go FTP for 1 hour in middle of 2-3 hour ride which isn't impacted by this diet at all. (Rode my last 3 centuries with over 10k climb with this diet...)

chandltp

I'm not saying this was the only issue, but my understanding is that most people take 2-3 weeks to become fully adapted to a low carb diet. If I'm reading this right you only gave yourself a week. This could have been the cause of you feeling so weak, since your body didn't have carbs for fuel and wasn't efficiently using fat.

Carbonfiberboy 

As I explained, I'd already gone through a long period of adapting my body to use fat efficiently during cycling. I defy anyone on a low-carb diet to hold lactate threshold or 90% of MHR for 45 minutes. Report your results here.

bored117 

I do quite regularly...

chandltp

I missed the part of your post where you said you were increasing your fat percentage.

However, you didn't mention what your macro nutrient percentages were as you increased your fat content in your diet. If carbohydrates were still the primary macro nutrient, your body still may have needed time to adjust to a low carb diet.

Granted, your experience doesn't seem to be that out of the ordinary either based on the majority of articles and personal accounts I've read, so the article I linked earlier may very well be representative of a minority of people that a can continue to cycling on a low carb diet without suffering a performance loss.

I know I've personally experienced decreased energy levels, as when I do I've added carbohydrates back in. But I've yet to push through that and continue eating low carb for 2-3 weeks to see if that changed.

Carbonfiberboy 

That would be because I did not increase my diet's fat content during my early season LSD phase. AFAIK there is no clinical evidence that shows that eating fat causes your body to burn it at a higher rate during aerobic exercise. Since body fat is so available, it doesn't seem to me that there's a cellular mechanism that connects burning to eating. In the same way, no matter how much sugar one eats, one cannot increase the amount burned over what one has trained to burn, assuming that one's glycogen stores are already topped up, just like one's almost unlimited fat stores are.

There could conceivably be some confusion over this because there is clinical evidence that shows that high volume training in the "fat-burning zone" increases the body's ability to do same, and there is also evidence that not eating carbs will mean that one will have great difficulty riding at intensities above that fat-burning zone. This could force the cyclist to do more or only LSD level training, increasing the ability to burn fat irrespective of diet. Cause and effect, easy to get them confused.

This is the whole point of LSD training: to increase the body's ability to burn fat during aerobic exercise. Then when one starts eating more during the ride and kicking the intensity up into the glycogen burning zone, it's like firing booster rockets. One's sustainable power from the combined energy sources will be found to have increased.

IOW, I don't see anything wrong with low-carbing it during the LSD phase, if that's what you want to do, but I don't think it's reasonable to expect to be able to put out full climbing or breakaway power while not eating carbs. There are vegan pros, no-gluten pros, HFCS pros, but AFAIK there are no low-carb pros.

In my little trial, I underestimated the amount of carbs I needed to eat to replenish my glycogen stores after a couple of draining rides.

chandltp

I think you just pinpointed the difference in our perspective. I rarely ride at full intensity. I ride long and slow because that's what I enjoy and that's how I get places.