Wednesday, 14 July 2010

Buns of Steel or Buns of Suet? Laugh Yourself Slim with the Daily Mail

The Daily Mail has an article entitled ‘How to Laugh Yourself Slim’. Laughing burns calories apparently.

Well, I read the tips and they provided the laugh component. I’ll let you know about the weight loss in time.

They’re ‘medically proven’, so that’s OK then.

"Sprinkle cinnamon into a yoghurt each day to burn fat. The spice is a powerful metabolism-raiser. Half a teaspoon a day is enough to burn an extra kilo a month"

This seems a rather alchemic approach. But perhaps gurning and puking burn more calories than I had realised.

"Train with friends and you'll lose a third more weight than if you go on your own. You'll maintain motivation by exercising socially, and benefit from mutual encouragement."

I can’t dismiss this one out of hand, but there is the important variable of who your friend is. What if it’s Johnny Vegas? (Masterful comedian, not an athlete). I’ve spent enough time in gyms watching people who use leg-press machines as armchairs to know that you need to be with someone focused or you’re better off solo.

And this one interested me most:

"Exercising first thing in the morning helps you to burn fat faster. You'll shed a kilo quicker than at any other time, as your body will be forced to tap into your fat reserves for energy."


I’m trying to remember the details of respiration and ATP from years ago. As I remember it, we have several fuel sources available to us and we use them in different combinations at different times.

There’s the glucose in your blood: highly available but there’s only a small quantity.

There’s the glycogen in your muscles and liver: pretty available, more plentiful but there's a limit.

And there’s the fat: very energetically dense, loads available (even in slim people) but a bit less immediate. And you need carbohydrate to burn it, like the priming charge of an explosion.

In an absolute emergency, there’s protein. But nobody wants to go there. It’s a desperate last measure and it hurts.

Anaerobic (energy metabolism without oxygen) exercise uses a lot of carbohydrate (glucose and glycogen) for fuel but produces by-products like lactic acid which soon inhibit performance. This kind of exercise is for emergencies and ‘sprinting’ – sudden, short-lived bouts of great effort like weight training with large weights, sprinting and jumping out of the way of buses.

Aerobic (energy metabolism with oxygen) exercise uses fat and carbohydrate, and gives a smoother performance over time. This type of metabolism is suited to sustained effort like walking or running steadily.

So exercising at a reasonable (not punishing) rate should tip the scales towards the fat-burning end of the continuum, whether you’re working out early or late.

If you run out of glycogen, that’s what cyclists call the ‘bonk’ and runners call the ‘wall’. It hurts. I’ve never done it. Jeff Galloway’s classic book on running describes it thus:

“Glycogen can be processed from fat, and from muscle protein. This is a very uncomfortable process and leaves a lot of waste … When nearby fat stores are used up and the exercising muscle absolutely demands glycogen, exercising muscle itself may be broken down”

So far, using fat for exercise seems to be primarily determined by the type of exercise. Unless of course, you’re so desperately short of glucose and glycogen first thing in the morning that you go straight to the ‘wall’. How carb. depleted are you in the morning then?

I’m shortish and female, so my recommended calorie intake is probably around 1800-2000 per day, I would imagine. (The NHS reckons about 2,000 - this is an average for women irrespective of age and height - and this more detailed BMR calculator reckons 1881)

Let’s call it 75-83 calories per hour to stay alive. That means that if I sleep for 8 hours, that’s a generous 600 to 660ish calories spent digesting, snoring and rolling over on the cat. That’s actually extremely generous, because I’m less active in bed than while awake … perhaps that’s my age ;-) Anyhow …

I run at about 9km per hour and am told by the machine that I’m burning about 650 calories per hour.

Marathon runners hit the wall at around 18-20 miles, 28-32km. At that rate, I’d hit it between 3.1-3.5 hours (Yes - I know I'm not Paula Radcliffe). Call it 2,000 calories. Most of running magazines concur that that’s about the right value.

That probably means that most of the time I have around 2,000 calories' worth of glucose in my blood and glycogen in my muscles and liver. The glucose will vary a bit, from around 4 or 5 mmol/l in the morning to a bit above 7 after a meal (I know this one, because a diabetic friend gouged me savagely with a needle while I was eating a lump of chocolate for pudding, and the blood test came out to 7.2). In any case, the nett glucose in your body is very small; the serious carb. reservoir is the glycogen.

So let’s say I spend about 600 (carb and fat?) calories sleeping and have a reservoir of about 2,000 calories before I hit the wall – then I have at least 1400 carb calories to spend on running when I get up. That’s over two hours of running.

I’m diligent, but not that diligent.

I can’t see how this ‘scientifically proven’ tip can work. I can also assure you that, despite running first thing in the morning without eating, I don’t hit the wall. I’m sure I’m still running with my glycogen reserves, in other words - same as if I was running in the evening after two meals.

If you're an exercise scientist, please tell me if I'm missing something.

I don’t suppose any of this matters in the grand cosmic scheme of things. Except that I worry that people feel they have to do all sorts of exotic things to be fit and healthy. I wonder if ‘scientifically proven’ lists like this actually create impediments to fitness.

In my experience, if you can get to the gym/park – just go. Don’t worry about the time of day.

Stop reading the Daily Mail for health tips.

And for god’s sake, don’t put cinnamon in your yoghurt!

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