Weight Loss Discussion Thread

[Chris S]

I think it estimated a 6000 calorie loss for a day's ride for me.

Isn't that the figure that Mark Beaumont had to chase every day though? And that was for 160km - I'm guessing you're talking about 200km.

I'm trying to "buy" a 1000kcals of deficit most days. If LS really is that optimistic, then I'm seriously depressed - that means I'll have to sit on the turbo all day!

[L CC]

"Not being the last up every single hill on a ride" is my motivation.

Of the East Anglian Big Hitters I am the strongest climber.

(This is a bit like saying of all the fish in my 3' garden pond, I am the largest, at 2" big...)

I think I need something more tangible. Y'know, like a new bike or something. You only deserve soot if you look something like an elf. Unfortunately my £s will not cover such things.

[jogler]

"Not being the last up every single hill on a ride" is my motivation.

This appears to be my purpose in life.Someone has to carry the lantern rouge & my thick skin & sloping shoulders are ideally suited to me providing this public service to prevent embarresement to anyone on the same ride as me.

[philip]

I think it may be rather more sensible with the Turbo figures. For "moderate" it gives about 600kcals/hr

That seems a lot.  Have i got the calculations wrong ?

600 kcal is 2520 kJ

One hour is 3600 seconds

That makes it about 700 W continual output for an hour 

The human body is not 100% efficient at converting food calories into mechanical work.  I remember estimates of the efficiency at about 25% for cycling, so the cycling power is more like 170W. I guess the rest is mostly heat.

[border-rider]

The human body is not 100% efficient at converting food calories into mechanical work. 

ah, of course

I wonder how that % changes with effort ? I suspect that at audax pace it's quite a bit higher; 25% might work for all-out turbo work I guess.

[border-rider]

At the moment my weight is coming off fairly quickly but I was starting from a position of being very overweight (approx 17 stones), I don’t know if this is a factor – I do know from previous experience that the rate of loss will probably slow down significantly as my weight drops under the 95-90kg mark (and if I don’t keep up the momentum I’ll have trouble keeping it off).  Currently lost 1.59 stones since the start of the year.

I’m exercising more- I haven’t missed a commute yet this year and as the round trip is 25+ miles this seems to help.  I’m eating a bit more carefully but certainly not dieting (I’m weighing carbs to ensure that I’m not under or overdoing it).  I’m also making sure that I eat breakfast every day, which also seems to help.

Possibly more significantly, I’m drinking a fair amount less alcohol, still probably a fair intake by most people’s standards but a big reduction for me.

I’m doing up to two turbo sessions on either Tuesday or Thursday and I seem to get much of my weight loss in the day following these efforts.  I’m also doing a long turbo or hilly ride at the weekend.

My problem has never been with shifting weight when motivated, it’s in finding the motivation and keeping the weight off once lost that I really struggle with.  My biggest battle with weight loss will be in the summer when all the rides I have planned for will be over.

I'm doing OK also.  9 kg off since NY, and I have a weight in stone that begins in 12 and not 14 now.

I've already got the mother-in-law "too thin" comment

I even managed to keep my weight down on last week's work trip to the US, despite the enforced inactivity and the lack of control over diet etc.  Not drinking alcohol (which I can tell you was a major temptation last week) is really helping me.  Not just the calories in the booze, but the way it messes up both my metabolism and my will power...

I'm still (just slightly) overweight according to my BMI, but I think that's more of an indication of the crudeness of BMI. 

[Chris S]

I've already got the mother-in-law "too thin" comment

LOL. That really winds me up.

"You're looking gaunt dear, are you feeling ok?"

Grrr....

[mattc]

'fitting into a big fancy white frock' worked really well

Excellent. I'll try that one  

 
I had similar thoughts when I read that  

I said: How the hell you get into those tight blue jeans?
She said: For starters you can buy me a drink.
[by Anon]

[simonp]

I think it may be rather more sensible with the Turbo figures. For "moderate" it gives about 600kcals/hr

That seems a lot.  Have i got the calculations wrong ?

600 kcal is 2520 kJ

One hour is 3600 seconds

That makes it about 700 W continual output for an hour 

The human body is not 100% efficient at converting food calories into mechanical work.  I remember estimates of the efficiency at about 25% for cycling, so the cycling power is more like 170W. I guess the rest is mostly heat.

yes, this causes confusion.

When you are using a powertap or other watt meter they are reporting output work done.  When converting to food energy you multiply by about 4.  It's easiest just to take the number of kJ and say that's the number of kcals.

Powertap reported 2400kJ for a 109km ride for me last weekend; this is about 2400kcal food energy.

Even then, I think this is going to be an underestimate because it's only measuring mechanical work that is delivered to the hub.  Mechanical work that is simply used to move your legs, maintain balance, etc, is not included.

If the Livestrong numbers are a bit high, then they're high by at most 50%.

[simonp]

The human body is not 100% efficient at converting food calories into mechanical work. 

ah, of course

I wonder how that % changes with effort ? I suspect that at audax pace it's quite a bit higher; 25% might work for all-out turbo work I guess.

Efficiency, Economy, and Endurance Performance

25% is at the high end of efficiency, apparently.

[mattc]

I thought improving the conversion %age was a major effect of all this flippin training we're doing? (especially the base level stuff)

Of course I don't know any figures for this effect, sorry ...

[border-rider]

25% is at the high end of efficiency, apparently.

Maybe, but that's for a 40 mile TT.  That'd be a pretty high power output.  I'd bet that at 200 km pace for us non-racing types, the power would be a lot less and the efficiency might be quite a bit higher

I just struggle to marry up the claimed calorie usage with the observed not-greatness of audax riding for weight-loss (even ignoring cakes )

edit: I did the same ride yesterday as I did last Tuesday.  I felt stronger and faster, and pushed myself far harder.  Result: ate more, finished considerably more wiped out in exactly the same overall time

[Butterfly]

I've already got the mother-in-law "too thin" comment

LOL. That really winds me up.

"You're looking gaunt dear, are you feeling ok?"

Grrr....

My favourite when I lost weight a few years ago came from my cousin -  "you look emancipated"! I did explain the difference between that and emaciated... (which I didn't anyway).

[clarion]

You look emancipated to me

[simonp]

25% is at the high end of efficiency, apparently.

Maybe, but that's for a 40 mile TT.  That'd be a pretty high power output.  I'd bet that at 200 km pace for us non-racing types, the power would be a lot less and the efficiency might be quite a bit higher

I just struggle to marry up the claimed calorie usage with the observed not-greatness of audax riding for weight-loss (even ignoring cakes )

edit: I did the same ride yesterday as I did last Tuesday.  I felt stronger and faster, and pushed myself far harder.  Result: ate more, finished considerably more wiped out in exactly the same overall time

Yet carbohydrate is burned more efficiently than fat. The problem is the lack of storage capacity, not efficiency. At low intensity you can cope on fat alone. At moderate to high intensity you need carbs.

"As exercise intensity increases, carbohydrate metabolism takes over. It is more efficient than fat metabolism, but has limited energy stores. "

[border-rider]

Yet carbohydrate is burned more efficiently than fat.

In terms of watts per unit oxygen, that is so.  I'm not sure it is in terms of overall energy efficiency though...

I found it interesting that, despite working a lot harder, I wasn't actually going that much faster

The previous ride, though, had seen a  dramatic time improvement on the first time I did  it, by working harder but not that hard.  I think that yesterday I was well into the region of diminishing returns.

[Chris S]

Does this inefficiency translate to calories taken in I wonder? If I eat 300 kcals of pasta - does my body get 300 kcals of energy from it? Seems unlikely.

How are the figures arrived at?

*thinks back to A-Level chemistry*

Do they still use Bomb Calorimeters?

[border-rider]

Does this inefficiency translate to calories taken in I wonder? If I eat 300 kcals of pasta - does my body get 300 kcals of energy from it? Seems unlikely.

Probably close to, if it's digested properly.

[Rich753]

But it's not digested "properly" - think sweetcorn, some seeds, nuts, they come out pretty much as they went in (put as delicately as I could!)

[Chris S]

That's true - but my (rather weak) example was pasta, which perhaps is better processed. FWIW I only eat Wholewheat pasta, so there is possibly more chemistry involved which will reduce the efficiency.

Anyway - interestingly enough - after all this, I couldn't resist weighing myself again this morning, and I'm 700g lighter than I was yesterday. This would suggest I am also susceptible to Bridget's "noise".

[simonp]

The food energy data for a given food already accounts for the fact that some of the food - roughage - can't be digested.

Efficiency is the conversion ratio from food energy to work done. This accounts for the energy to digest the food and the losses in converting the chemical energy in food to mechanical work. Hence if you eat 300kcal of pasta you can only do 60-75kcal of work. Livestrong already allows for this.

[L CC]

This all reminds me of diet formulation as a student. You're going to start talking about the heat increment of feeding, losses to atmosphere and relative digestability next.

As long as nobody starts mentioning how lower digestibilty affects butterfat content, I may escape untarnished...

[mattc]

The food energy data for a given food already accounts for the fact that some of the food - roughage - can't be digested.

Yup. The stuff that goes through relatively unscathed - sweetcorn* and nutshells - has no calories that we can extract.

(*I don't know the proper term for the outer bit of a sweetcorn thingy.)

[vorsprung]

You look emancipated to me

For me, the first place that fat disappears is from the face
So I "look emancipated" but I have still a spare tire

[Andrij]

Wow.  Eating less + exercising more = weight loss.  Who could have guessed? 

Yes, a simple formula, but surprisingly difficult to follow consistently.  If I can repeat last week's loss regularly then there could be a svelte new me by Easter.  Then comes the hard part — staying that way.