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Tuesday, March 11, 2008

Obese Folks: on Your Feet!

One of the most common accusations faced by people with weight problems is that they are simply lazy and just lack the motivation to be active (the other one is that they simply eat too much!).

It turns out that some obese people may in fact be less active than lean individuals. For e.g., a recent study by Darcy Johannsen and colleagues from Iowa State University published in OBESITY, used state-of-the-art activity monitoring technology (IDEAA) to examine in detail the activity patterns of 20 free-living lean and obese women over 14 days. Total energy expenditure was measured using doubly labeled water, body composition was measured using dual energy X-ray absorptiometry.

The main finding was that even after correction for increased body mass, obese women on average expended around 300 KCal less in physical activity per day than their lean counterparts. Overall, obese women sat 2.5 hrs more each day and stood 2 hrs less than the lean women. They also spent only half the time being physically active compared to lean women.

This finding is not new. Previous studies have noted that obese individuals spend less time on their feet and expend less energy through non-exercise thermogenesis (fidgeting). Importantly, intervention studies have shown that this is not corrected by weight loss - rather, the tendency to be less active appears to be innate, i.e. not due to the excess weight.

Well, as usual, Johannson and colleagues conclude their paper with the profound insight that if only obese women adopted the activity pattern of lean women, they wouldn't be obese - and that is where the logic breaks down.

In fact, this is very much like saying that, "if only depressed people could be less sad and, like "normal" people, show more interest in things, they'd be so less depressed".

The issue is not whether or not obese people move less - the question is why they do so. If the tendency to be less physically active and spend less time on their feet is innate - i.e. a character trait that is determined largely by genetics, then trying to get someone with this trait to be more physically active is likely to be difficult.

Perhaps one way of thinking about this is to reverse the argument. If, for a moment, we assumed that being lean was really the problem, then we'd have to teach lean people to really try to sit down more and to focus on being less active, so that they could gain weight. Anyone who believes that it would probably be difficult to teach lean people to sit still, to stop fidgeting and to simply be less active, should realise that for exactly the same reasons it may be unreasonable to expect the opposite of people with excess weight.

Not to say it is impossible - but in both cases it would take a special focus, a lot of resolve and perhaps constant reminding as it goes against their "natural" disposition.

While in today's obesogenic environment the natural disposition to fidget and rush around works to the advantage of lean people, the natural disposition to sit down and not rush around (indeed a "sensible" behaviour in a calorically frugal environment) is a handicap.

Again, the results of such studies should not be interpreted in the sense of: "Aha, so now we know what is "wrong" with people who have obesity - they are indeed lazy!". Rather they should be interpreted in the sense of: "Aha, so that is why people with obesity have such a hard time keeping their weight off - they are simply "programmed" against a senseless waste of energy".

This of course is not an excuse to do nothing - it just means that we must appreciate the extra effort that is required.

In other words, when lean people run around - that's just their nature, they can't help it - it's not because they are extra smart or better people. In fact, now that we have seen this research we should realise that when people who have obesity run around (even a little) this is certainly highly commendable, as we now know that they have to consciously make this extra effort despite their innate tendency to preserve energy.

Creating an environment that fosters time on your feet will serve everyone - the lean people will love it (or not care), those with weight problems will benefit without having to make a conscious effort. Time for more stand-up meetings?


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