Fat Story

I was arguing last night that one cause of obesity might be reduced metabolic rates in warmer housing, workplace, and transport internal environments.

Today I thought I’d take a stab at estimating what the difference might be, using Humphreys and Nicol’s 1970 BRS study of Theoretical and Practical Aspects of thermal comfort. For this I needed to estimate what mean room temperatures prevail today, and prevailed in the 1950s. And also what clothing levels prevailed now and then.

From my personal memories of life in a detached English house in about 1955, I guessed at a mean temperature of about 12º C in winter, largely because only two rooms had any heating in them (in the form of coal fires). And even these rooms were seldom very warm. I’d estimate that they were never much warmer than about 18º C, and the bedrooms and kitchen and bathroom and hall were about 10º C. So a mean internal temperature of 12º C seemed about right.

I also remember how my grandfather dressed, in flannel trousers and tweed jacket and shirt and waistcoat with woollen long johns underneath. Given an ordinary suit has a thermal resistance of 1 clo, I guessed that his outfit was about 1.3 clo.

Then I compared it with now, when many people keep their houses very warm, maybe 25º C, and wear jeans and T-shirts that are probably about 0.5 clo.

metabolicRateGiven these numbers, I plugged them into the equation for metabolic rate in the Humphreys and Nicol study (right), and found that in the 1950s the required metabolic rate to maintain thermal comfort was about 88 Watts per squ metre of body surface, while the required metabolic rate today was about 60 Watts per square metre. 88 W/m² corresponds to standing doing light work, while 60 W/m² corresponds to sitting.

Which seemed about right. In most homes today, people seem to spend most of their time sitting. But back in the 1950s there was quite a lot that needed doing. Back then we had 3 meals a day, and they all required cooking to be done. But on top of that there was hand-washing clothes and sheets, squeezing most of the water out of them in a mangle, and hanging them up to dry. There was also ironing, and house-cleaning. And the two coal fires needed to have coal added periodically, and the coal hods beside them had to be filled once or twice a day from the coal shed outside. And on top of that there were clothes needed to be darned. The result was that the household was pretty much a hive of activity all day. And I used to help out, laying fires, fetching coal, blending cake and pastry mixes. We had to make more or less everything ourselves.

Nowadays  the clothes are put in a washing machine which may also include a spin and tumble drier. Cooking just means sticking something in a microwave for a few minutes. And if your socks get holes in them, you just buy new ones. And you have a vacuum cleaner that you can run over the floor every few days. So there’s not very much to do, and you can spend most of your time sitting and watching TV or listening to the radio or updating your Facebook page.

88 W/m² over 1.6 square metres of body surface area for an entire day works out at a bit over 12000 kJ / day, or 2900 Calories per day. And 60 W/m² works out at a bit over 8000 kJ/day, or 2000 Calories per day. According to Chris Snowdon, 2000 Calories/day is our current energy consumption per day. And according to George Orwell, 2900 Calories/day is what people were consuming in 1946. So we’re now consuming a third less food energy than we did 70 years ago.

How might that have resulted in an obesity “epidemic”? One plausible explanation is that people tend to carry on eating the same amounts of food, and also wearing the same clothes, as they are accustomed to. And this will mean that they will be generally eating more than they need to, and the excess energy gradually accumulates as body fat. Even if people do reduce their food intake (as clearly thy have been), their response is likely to always be lagging behind their actual circumstances, like a car cornering on the outside of a bend.

The same would be true if they needed to consume more food and wear more clothes. The lagging response to this new circumstance would be that they would eat too little and wear too few clothes, and get very thin. The obesity epidemic would be followed by an anorexia epidemic..

The lagging response would have been particularly notable when people moved from a coal-fire-heated 1950s house into a centrally-heated, double-glazed 1980s house, but carried on wearing the same clothes and eating the same food as they had before. And this probably happened very frequently when 1950s houses were demolished and rebuilt, as was happening continually throughout the 1960s, 70s, and 80s.. Since it was generally the working classes who made this sort of rapid transition as they were moved out of their back-to-back houses into tower blocks, the problem would have been the greatest there – the middle classes instead gradually adding central heating and double glazing and loft insulation, and gradually adapting over a much longer period, 

Other factors may not have helped. Recent decades have seen a slightly warmer climate than 70 years ago (“global warming”), and this would have meant slightly higher room temperatures, and a need for an even more greatly reduced food energy intake. 

And just when smoking would have helped reduce appetite, smoking is being very strongly discouraged, making it even harder for people to reduce food consumption.

One may speculate that clothing fashions and diet fads may have been as much driven by the need to wear less less and eat less as any purely cultural trend. For example, mini-skirted girls would have lost heat energy faster than their more staid peers, and been slimmer as a consequence. And if they were always dieting, it was because they always needed to be reducing their food energy consumption. Culinary fashions might also be explained in the same way. Nouvelle Cuisine, for example, consisted of minute portions of exquisite food. And something like this might be the culinary future, with food producers hiring armies of chefs to make their products more tasty, while simultaneously reducing their size and energy content.

What about regular exercise? A half hour of brisk walking every day would burn off about 650 kJ or 155 Calories. That’s the energy content of about half of a small bar of Cadbury’s milk chocolate – a drop in the ocean.. If exercise is to be used to offset the effect of living in warm houses equipped with the latest labour-saving devices, while eating the same amounts of food as in prior eras, the exercise must be both intense and prolonged. And this may explain the rise of gymnasiums offering just such intense and prolonged varieties of exercise. Just like mini-skirts, they are a way of preventing obesity.

In summary, the argument being made is that the gradual introduction of warmer houses with ever more numerous labour-saving devices over the past 70 years has required a continual compensatory reduction in food energy consumption and clothing. Such adjustments were gradually made, but more slowly than was necessary. The result was a long term obesity “epidemic” that was the result of steadily falling energy consumption.This is not the fault of food manufacturers. Nor is it the result of gluttony. The problem is instead that people tend to eat and dress in the way to which they are accustomed, but what was once customary and adequate has now become excessive..

About Frank Davis

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22 Responses to Fat Story

  1. I’ll have to remember all this the next time I go on a diet.

    – MJM, clocking in at 115 (er… pounds, not kilos!)

  2. waltc says:

    I still believe –and it’s confirmed unwittingly by the CDC– that the rise in obesity is in direct inverse proportion to drop in smoking rates. On my computer (on iPad now) I’ve got links that show that tho I’m sure I’ve posted them here before. Anecdotally, I’ve known at least 4 people who quit smoking and gained tremendous amts of weight and suffered from the weight gain more than they ever would have from continuing to smoke. As for the rest, there were far too many fat girls walking around in minis, a grave esthetic error.

  3. Some French bloke says:

    “A half hour of brisk walking every day would burn off about 250 kJ or 60 Calories”

    Yet, according to health.howstuffworks.com “a brisk walk, covering three-and-a-half miles in an hour, burns about 280 calories. When repeated each day, this excellent habit burns about 3,900 calories — more than a pound of fat — every 2 weeks”
    It would seem safe to say, then, that in addition to “the gradual introduction of warmer houses with ever more numerous labour-saving devices”, the closure of countless UK railway lines before and after the ‘Beeching cuts’ (7000 route miles between 1950 and 1973), and of those thousands of railway stations people often had to walk to an from, made a similar contribution to this gradual loss of balance. The obesity ‘epidemic’ is also connected to the tyranny of road transport!

    • Frank Davis says:

      There’s walking and walking, and my man is actually walking rather slowly. According to this source, walking at 5 km/hr burns 360 Watts, which is about 1300 kJ/hr or 310 Calories.

      I think I’ll make him walk a bit faster.

    • It doesn’t say, but I”m assuming that the “brisk walk” would actually have to last for an hour to have the claimed effect. Several notes:

      1) Spending an hour out of every 16 waking hours doing nothing more productive than walking seems rather a waste of life. Easier to skip a donut or two. BUT…. if you substitute wallking for driving a mile or two to work, you save the time spent driving, plus the time/effort of earning the money for gas, plus possibly the huge amount of time/effort put into buying/maintaining/insuring a car!

      2) The calorie burning is very imprecise. E.G. it would seem pretty likely that a 350 pounder would burn a lot more than a 150 pounder while taking that walk.

      3) The speed of 3.5mph is indeed a VERY “brisk” walk — not at all a casual stroll.

      4) I forget the caloric equivalent, but you might have more fun having sex instead. Jes’ sayin’ ….

      :>
      MJM

  4. woodsy42 says:

    I have always struggled to keep my weight down. When I went from self-employment with quite a bit of active time outside to an indoor, heated, mainly deskbound job I put on a stone in a few weeks. It took years to get rid of it. When I stopped smoking the same happened, again years of self denial to try and reduce it. I can fully accept your suggestion that lifestyle is a huge factor, although I believe there is also a large and mostly ignored genetic factor.

  5. garyk30 says:

    Being overweight is a curious thing as they keep changing the standards.

    In 1998 the lower standard for overweight went from a BMI of 27 to a BMI of 25 and I went from normal weight to overweight with out gaining a pound.

    For those over 65 years of age, normal BMI goes up to 29.9. So a few years ago, I went from being overweight to being normal weight again without losing a pound.

    • garyk30 says:

      Then there is this:

      Health organizations consider a BMI between 18.5 and 24.9 normal weight, between 25 and 29.9 overweight, and 30 or above obese.
      They further subdivide the obese category, though – with a BMI between 30 and 34.9 designated grade-1 obesity, and anything above 35 grades 2 or 3.

      The researchers reviewed databases of medical research and found 97 studies that looked at weight and mortality risk.
      Combined, Flegal and her colleagues had information on about 2.9 million people from around the world and 270,000 deaths.

      Being obese – in general – was linked to an 18 percent greater risk of death, compared to being normal weight.
      Being severely obese – grades 2 and 3 – was linked to a 29 percent greater risk of death.

      However, being merely overweight was linked to a 6 percent decreased risk of death compared to a normal weight person, while being slightly (grade 1) obese was linked to a 5 percent lower risk.

      The study cannot say why there seems to be a link between being overweight or slightly obese and a lower risk of death.

      • nisakiman says:

        Probably because overweight people tend to be bon viveurs, and people who enjoy life and what it has to offer will be of a happier disposition and not suffer from the stresses of a guilt complex.

        • nisakiman says:

          Unless, of course, they are foolish enough to listen to (and believe) ‘Public Health’ and its doom-mongering.

  6. junican says:

    I can’t think of anything more boring that deliberately going for a ‘brisk walk’ every day just to burn calories, or going to a gym for that reason either. I do plenty of gentle exercise pottering about in the garden and the house. I see exercise as a means of keeping muscular tone and keeping the major organs in good shape. Just keeping busy is enough.
    Man is a walking animal with the ability to run like hell for short periods of time. That’s why we got up off four legs.
    I suspect that population wide statistics are not much use for comparison purpose with the situation decades ago. In those days, many men worked in laborious jobs. That percentage would have stayed slim-ish. As Frank has pointed out, few women went to work – they were busy at home washing and ironing, going to the shop daily, etc. Now, much fewer men work in such jobs and the tasks of women, even if they do not work, are much reduced, so the percentage today of ‘hard workers and busy housewives’ would be much smaller, with the consequent tendency to put weight on.
    I doubt that all the blather about sugar and salt etc will make the slightest bit of difference. The Fat Zealots are using the tobacco template – attack the Big Food Industry – but they are wasting their time (and our money). There are few massive food producers. Instead there are masses of small restaurants and small take-aways. Eating is an individual thing, which does not lend itself to mass propaganda.

    • harleyrider1978 says:

      That’s it Cousin………….the same attack plan so it wont be real hard to know whats coming next………….

  7. cherie79 says:

    I was never overweight in my life until I stopped smoking for three months and gained 28 lbs. I decided I would rather smoke, took me another three months to lose it – never again.

  8. harleyrider1978 says:

    BTW folks today I drove from Clarksville tn back home about 80 miles on the backroads…………Those tobacco farmers have 2 crops coming in this year as they are Fire curing their 1st crop right now today!There will be another crop by November ready for fire curing.

  9. DP says:

    Dear Mr Davis

    My father stopped smoking c 40-50 per day as a money saving exercise – we lived abroad where tobacco was cheap and were coming home “for good”. He decided UK prices were too high. He piled on the pounds, in line with contemporary folklore.

    Low impact perambulatory exercise over many miles can be had as a pleasurable experience if you walk dogs* – and get paid for it. Beats driving to the gym to pay to listen to atrocious music and breathe second hand sweat (SHS).

    DP
    * Must like dogs and be prepared for the occasional mishap – Brodie the Staffie pup went AWOL this afternoon and his Mum had to collect him from a house 2 miles from home. I spent the time reading the blogs …

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