fatbrit

AIinsworth B E et al. in "Compendium of Physical Activities: An update of activity codes and MET intensities." Med Sci Sports Exerc 2000;32 (Suppl):S498-S516 give values ranging from 57 calories/mile for a 100 lb walker at 2 mph to 218 calories/mile for a 300 lb walker at 5 mph. That's a 4x difference between the two ends of the scale.

I believe weight and speed are indeed significant factors in the calculation.

dunroving

Significant internal energy cost due to extra energy expended balancing that does not contribute to locomotion.

Well, you did ask.

Cape Blue

I suspect over the next 10-20 years we will see a drift away from the thoughts of its all down to personal responsibility, self control, bit of exercise, fat people should put down the pies (etc) and more towards obesity and its causes as a medical problem.

The judgemental amongst society see excess calories as the cause of the problem, whereas I suspect we will start to realize that this is just another symptom - as I mentioned earlier, if your metabolic system has been impacted by the high use of crack-food and can no longer work properly, and if this leads to excess insulin in one's blood stream, then people's bodies are unable to access the fat stores that they normally would.

This leaves the situation where their body is calling out for nourishment even though they appear to have plenty of (non-accessible) reserves - basically they are starving hungry and each new meal uses the excess insulin to wash the blood sugar into fat cells, but the reverse process of glycogen removing that sugar for muscle (etc) use is not functioning.

Of course, it could be that they are all just fat-knackers who have no self-respect or self-control

dunroving

Yes, I know the Compendium and also know the author pretty well. The problem with the compendium is that the data come from different studies and so many of the differences between/within different activities and body sizes are due to study design.

A 300lb person is not average - as per my prior email, I was asking an approximate question about someone who is approximately average weight.

Also, you are mixing weight AND speed - the higher value is more to do with the higher weight than the higher speed. And 5 mph is not really within normal (or even achievable, for most people) walking speeds, so yes it would cause a higher energy expenditure per unit distance because of mechanical and therefore metabolic inefficiency. Note in my earlier email I said speed isn't a factor for normal walking speeds of between 2 mph and 4 mph.

American College of Sports Medicine metabolic equation is used by all self-respecting exercise scientists to predict VO2 (and thereby energy expenditure) from walking, based on measuring energy expenditure during controlled laboratory studies. The equation for walking on a level gradient is as follows:

VO2(ml/kg/min) = (.1*speed) + 3.5

Where speed is in meters/min - and the 3.5 should not be added if you want NET energy expenditure (i.e., energy cost of the activity only). The thing is we all consume 3.5 ml/kg/min at rest - so the 3.5 should not be included as part of the activity energy expenditure (and also explains why GROSS energy expenditure - as per compendium - is confounded by time/speed).

1 ml/kg/min of O2 is equivalent to 1 kcal/kg/min (depending on the relative proportion of the fuel surce - protein, fat, or carbohydrates, indicated by measured respiratory quotient), so you can check my calculations for the following yourself, if you like:

Kcals in a 62.5 gram Mars bar = approx. 280

Number of kcals to walk a mile for someone who is:

120 lb = 42 (so 6.7 miles to use up 280 kcals)
150 lb = 52 (so 5.4 miles)
180 lb = 63 (so 4.4 miles)

The scariest statistic is that 1 lb of body fat contains 3,500 kcals – so to burn off 1 lb of body fat, a person weighing 150 lb would have to walk about 83 miles ... that is why I said the “fat-burning” role of physical activity in weight management is trivial (but there are lots of other reasons to incorporate physical activity in a weight-management program).

p.s. I have published research on the energy consumption of walking, so I didn't just use Google or Wikipedia for the above.

Sally Redux

Still don't see why the blame lies with the NHS.

dunroving

Because everything is the government's fault, I suppose.

"I want to set a precedent so no one else has to get to the same size - and to put something back into society," he told the newspaper.

- so I presume he'll be donating any award from the court case to charity... not.

ldyinlv

I agree Sally.

Giantaxe

Apparently the blame, like everything else this particular "Scotch" individual posts on, resides with the Labour government.

chartreuse

Really? I used to average about 7mph, when I used to walk 5 miles a day (broken down into mile and mile-and-a-half chunks). Mind, a lot of that was through the Kings Cross area...

dunroving

That's about 8 min 34 sec per mile - almost impossible for most people to walk that fast (I mean regular walking, not race-walking technique). World-class race walkers cover a mile in about 7 mins (women, that is).

In 1-mile walk tests (fitness testing), I find most people can't walk a mile much faster than 12 mins (5 mph).

Also, in our treadmill research, even fit, healthy young adults struggle to walk above 4 mph for any meaningful length of time ... and from observational studies of pedestrians, typical walking speed is about 3 mph.

Derrygal

I have no idea - I'm guessing about 3 miles?

Derrygal

Sorry - just realized you already answered this - wow - way more than I thought!! I won't eating many Mars bars from now on!!

ldyinlv

That explains alot about the size of my butt..

dunroving

At least your sense of humour is in good shape.

Jerseygirl

Yet another case of people not taking responsibity for their own actions...much easier to blame others.