Impact of changes in body fat levels on cycling uphill?

ColinJ

Being overweight really impacts hill-climbing ability. Fat is a load which needs to be carted up hill and it doesn't help at all. I can do the maths and can work out how much extra power would be required to cope with a given amount of extra weight on a given gradient at a given speed.

Now, there is something I'm beginning to wonder about and this is what I'd like an answer to:

Is there a metabolic cost to having high body fat? I'm thinking perhaps in terms of having to pump blood round extra fatty tissues or something like that. Is it worse than just being dead weight and an insulator? Put it this way - If I was climbing a steep hill (slowly, so we can pretty much ignore wind resistance) and could magically reduce my body fat by 10 pounds, would that have more effect than just jumping onto a bike that weighed 10 pounds less?Yes, I know that losing the weight off me would be cheaper !

I aim to go down from 215 pounds in weight to about 174. When fat I ride my Basso (lower gears) which weighs about 22 pounds. When slim, I'd ride my Cannondale which is more like 17 pounds. I reckon I carry about 10 pounds of water, tools and clothes when riding.

Total riding weight (fat) = 215 + 22 + 10 = 247 pounds (yikes!)
Total riding weight (slim) = 174 + 17 + 10 = 201 pounds

If the cost of fat is only dead weight, then (given a similar level of fitness) I ought to be able to climb my steep hill in about 201/247 (~81%) of the time. I feel almost sure that I was faster uphill when slim than just the difference in weight would explain, but perhaps I'm fooling myself - I did a lot of cycling that year so maybe I was lighter and fitter.

unclemalc

There must be a cut-off point where 'power-to-weight' ratios come into play. I personally carry too much weight and so I have not gone down the carbon route (yet) because if I want to reduce the weight of me+bike on the road, its cheaper to reduce the pie intake and slim down. I have been doing that steadily for this year and it shows in my stamina increase and general well-being.
Its a circular thing - eat less crap, lose weight (gradually, mind) improve and increase all aspects of cycling, thus lose more weight and so on.
This week I went up my usual climb to finish my ride and there were 8 lads on MTBs mucking about in front. I went past them without effort one by one and as I passed the last one, only a third of the way up, I heard him say " Christ, look at him..."
Now it might have been a comment on my new jersey, but I like to think it was a comment on the style....
At least he didn't say "Look at that fat old fart go..."

Mettan

unclemalc wrote:

Its a circular thing - eat less crap, lose weight (gradually, mind) improve and increase all aspects of cycling, thus lose more weight and so on.

Yep, that's a good point. After 3 - 6 months of regular riding (and sensible eating) it does all start come together.

ColinJ

ColinJ wrote:

If the cost of fat is only dead weight, then (given a similar level of fitness) I ought to be able to climb my steep hill in about 201/247 (~81%) of the time. I feel almost sure that I was faster uphill when slim than just the difference in weight would explain, but perhaps I'm fooling myself - I did a lot of cycling that year so maybe I was lighter and fitter.

I've been reading some interesting articles (including this one) and doing some thinking since I made the original post...

I'm 6' 1" tall and of medium build. When I was a student I lost a lot of weight. At my lowest, I was about 10 stone 12 pounds (152 pounds, 69 kg). I was so puny that I could get a roll of Sellotape over my wrist and push it all the way up to my armpit!

Years went by and I got very fat, then I took up cycling. My weight came down steadily and I got fitter but I still weighed about 13 stone (182 pounds, 83 kg). I was still pretty mediocre going uphill on my bike.

Then one year I got serious and started doing a lot more cycling, including regular intense intervals on my turbo-trainer. I got my weight down to 11 stone 10 pounds (164 pounds, 75 kg) and my hill-climbing ability was transformed. The thing is - I looked incredibly scrawny even though I weighed 12 pounds (5.5 kg) more than I had as a student. My ribs were sticking out and the skin on my hands was almost transparent.

It dawns on me now, that I'd actually lost a lot more fat then I thought I had, but I'd also put on a lot of muscle so my weight hadn't dropped as much as it would have done otherwise. Because of my increased muscle and decreased weight, my power-to-weight ratio had rocketed.

So... to answer my own question - I think that fat is just dead weight, and a nuisance when riding hard in hot weather because it makes overheating more likely.

Merely dieting to lose weight is counter-productive because muscle will be lost as well, so power-to-weight ratio won't improve that much and also - daily calorie requirement would drop (muscle tissue isn't dead weight like fat - it needs energy to maintain it) so calorie intake would have to be reduced further, more muscle would be lost and so on.

It all makes sense to me now. The body is genetically programmed to store energy as fat in case of future food shortages. In the western world, most people don't have a shortage of food, so many people tend to overeat regularly and the weight piles on. Eventually, they try and diet to get rid of the fat, but the body thinks "Warning - starvation mode!" and starts to shut down the metabolism and shed muscle since that uses up energy even when not being used. If we exercise intensely and reduce calorie intake only slightly, the body doesn't go into starvation mode, but builds extra muscle because it is obviously needed. This extra muscle burns up even more energy - bonus!

So, if I've got it right...

Dieting -> starvation mode -> metabolic shutdown + muscle loss -> less activity -> plateau -> giving up -> gaining weight again (the classic 'yo yo' diet effect).

Vigorous exercise + slight calorie reduction -> calories burned when exercising -> bigger muscles -> faster metabolism (extra calories burned even at rest) -> overall weight loss and performance increase beyond what just the weight loss would suggest.

Perhaps that was all very obvious to everyone else, but I used to look on losing fat as just losing 'dead weight'. Now that I can see that there is more to it than that, I feel even more motivated to get on with it .





(Of course, I could just be talking a load of old b*llocks !)

unclemalc

Outstanding. Post it on all the topics relating to this sort of thing.
May you increasingly soar up those hills.