Tuesday, 30 January 2007

How to... yo yo diet

If you are at all conscious about your body, and lets face it most of us are (not as much with the guys but still), then at one point or another we have been at least tempted to try some sort of fad diet.

The idea behind most of these (apart from making lots of money for their creators) is that be eating only certain things (ie no carbs, or no fats) or eating in certain ways (only raw food) or by substituting "supplement shakes" for meals one can lose weight.

Of course there is one other method by which people often try to lose weight and that is simply by starving themselves. And it is this rather than the others that I want to focus on today.

Our bodies are wonderful mechanism - in times of plenty we store the food for times where food is rather scarce, however one other thing is that in times of scarcity our bodies will also slowdown so that the stores we have can be made to last as long as possible, this is especially useful if you do not know when more food will be available again.

So what happens when you try to lose weight by cutting calories alone:

  1. Your body thinks (rightly) that it is a time of scarcity of food
  2. So your metabolism slows down to conserve your food stores -fats, glycogen (stored carbs) and protein
  3. Since you are still not taking in enough food to subsist, even with the reduced metabolism you body starts to burn its stores.
  4. Your body is used to operating mainly of carbohydrates since these are the easiest to use so you store of these, glycogen, is used first.
  5. This leads to a quick loss of a couple of kilos since the break down of glycogen releases a lot of water.
  6. Once the glycogen is used up the weight loss slows, and the body now must turn to an alternate fuel.
  7. The blood-brain barrier is impermeable to fats, so either that stored fats have to be broken down (a difficult task) or instead protein can be used (what actually tends to happen)
  8. The primary weight loss now is muscle wastage as the proteins from the muscles are used in respiration (which is the process of releasing stored energy not the process of breathing in and out, which is a small part of the former).
  9. If this continues for some time important muscles such as the heart can begin to degrade, which as you can imagine causes no end of life threatening problems.
  10. If at some point you do stop fasting, you body suddenly goes into "time of plenty" mode (which it is at least relative to the fasting) in which the main aim is to restore the used body stores of energy (and of which fat is the most efficient).

Now some people go through this process and are quite pleased with their weight loss, which is why the get to step 10, unfortunately this leads them to put on weight and quite often this is more than they lost so they start again. So it becomes a bit of "Lather, Rinse, Repeat"and of course this can go on and on and on ... Hence the "yo-yo diet" moniker.

Of course the observant of you will have noted that no where did I mention using the stored fats, this is where exercise comes in to the equation, you can only burn fat through prolonged aerobic exercise - ie long and relatively slow (and steady) exercise such as jogging, swimming, and walking that sort of thing