5 Comments »Posted on Saturday 9 May 2009 at 12:44 pm by Sam Wong
In Health & Medicine

Quite understandably, Jacob loves to rant on these pages about the bullshit scientific formula stories that reduce complex processes into a nice-looking arrangement of a few variables, contributing precisely nothing to the sum of human knowledge. But when it comes to the regulation of body weight, the equation is both incontrovertibly true and cruelly simple:

Weight gain = Energy intake – Energy expenditure

If you want to lose weight then, it’s a simple matter of eating less and doing more exercise. Meanwhile, the alarming rise in obesity levels in developed countries in recent decades can be put down to some combination of eating more and doing less. For those concerned with halting the upward trend, the question of which side of the equation to focus on has been a matter of debate.

To address this issue, scientists at the World Health Organization Collaborating Centre for Obesity Prevention at Deakin University in Australia studied 1,399 adults and 963 children to find out the rate at which they burn calories in daily life. From this, they worked out how many calories an adult needs to eat to maintain a stable weight and how much a child needs to eat to follow a normal growth curve. Based on these numbers and data on food consumption in the United States since the 1970s, they calculated how much weight they would expect the average American to have gained in this time if energy expenditure had remained unchanged.

In children, the expected weight gain exactly matched the actual figures, suggesting that diet alone could account for the rise in childhood obesity. In adults, the expected weight gain was 10.8kg, compared with the actual figure of 8.6kg. It seems then, that increased food consumption could account for the rise in obesity in the adult population as well, and in fact an increase in energy expenditure might be offsetting the average American’s overeating to make for a less substantial weight gain.

The centre’s director, Professor Boyd Swinburn, presented their findings at the European Congress on Obesity in Amsterdam yesterday. He said that the results would be similar in other developed countries. ‘To return to the average weights of the 1970s, we would need to reverse the increased food intake of about 350 calories a day for children (about one can of fizzy drink and a small portion of French fries) and 500 calories a day for adults (about one large hamburger),’ he said. ‘Alternatively, we could achieve similar results by increasing physical activity by about 150 minutes a day of extra walking for children and 110 minutes for adults, but realistically, although a combination of both is needed, the focus would have to be on reducing calorie intake.’

I think the use of simple maths like this to figure out something important is great. Now we must think about how to make people eat less, which we know is tricky because we’ve been trying to do that for a while. Food labelling, as Jacob discusses in the previous post, certainly has a role to play. Education is important too, but clearly there are no quick fixes to the obesity epidemic.


  1. 5 Comments

  2. As Prof Swinbrun says, if you want to lose weight calorie reduction really is the way to go. Walking for an hour will burn around 300 calories, roughly the same number you’ll gain by eating just one Mars bar.

    Part of the problem is portion size. I was walking past a bakery this morning and glanced at the enticing chocolate muffins in the window. About the size of my fist, they easily had enough calories to satisfy two people’s breakfast needs – possibly even three.

    Now, there is no point regulating a ceiling on portions. Give muffins a maximum size, and many people will simply buy two. It’s really a cultural problem of more = better, and I’m not sure how you fix that. Rationing, maybe?!

    By Jacob Aron on Saturday 9 May, 2009 at 1:15 pm

  3. I’ve just had a Eureka moment. What if we take a leaf out of the ant-smoking book and make highly calorific foods carry horrific photos of obese people? Or is that a bit extreme? It would certainly make the muffin look a little less appealing.

    By Sam Wong on Tuesday 12 May, 2009 at 12:08 pm

  4. Good luck getting the industry to agree to that!

    By Jacob Aron on Tuesday 12 May, 2009 at 12:26 pm

  5. They don’t have to. Do you think the cigarette industry agreed to have pictures of disease on their packets?

    By Sam Wong on Thursday 14 May, 2009 at 12:12 pm

  6. No, of course not, but government can’t just do what it likes. The industry has to be on board in some way, even if it’s just “do this or face something even worse”!

    By Jacob Aron on Thursday 14 May, 2009 at 12:48 pm

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