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Dieting

 

(a recent article in New Scientist (19 january 2008, p.17) confirms the role of insulin and combinations of foods in the accumulation of fat tissue)

Why

In 2002 I felt too fat.  74kg had always been my adult weight but I began to put on more weight from age fifty and went up to 84kg.  Ten kg more!  That's like carrying a six-pack of 1.5 litre water bottles with you all the time!

six pack of 1.5l water bottles

(they actually weigh only somewhat more than 9kg).

Talking to my sister who is a pharmacist my brother in law who is a doctor who also felt he was putting on weight, we decided to start a friendly competition to reduce our weight by 10kg over the next ten months, beginning in March 2002.

The works

Anything you eat gets digested, transformed, transported inside your body and eventually used for energy, for storage (fat), or for building (bones, tissues).

The processes of digestion, transformation and use are called "metabolism".  It is impossible to dissociate slimming or fattening from your metabolism.

Except for a small percentage of people, we all share the same basic metabolism.  If you have a weight problem then you cannot successfully keep your weight under control unless you understand how human metabolism works.

Most of the "fat-problem" comes from not understanding how fat forms:  fat comes from sugar.  Fat does not come from eating fat, just like cows don't give green milk from eating green grass.  You also do not get rid of fat by exercising unless you change your eating habits at the same time.

Fat is converted sugar, and the conversion is triggered by insulin.  If your insulin reaction works however, there is also a reaction that will store the newly formed fat away, and much other fat that you also ate may also be stored as well.  So be careful with eating fat nevertheless.

There is just this rule:  if you want to keep slim, keep your body from converting sugars into body fat.  That effectively means not setting off your insulin reaction.  Your insulin reaction starts as soon as you eat sugars.  Therefore, do not start a meal with a piece of bread.  Don't eat a biscuit a short time before a main meal.

How

As my sister had pointed out, a lot of my food had too much sugar in it.  I made some simple switches:  breakfast of natural müsli instead of the ones with sugar added (5%!) and natural yoghurt instead of sweetened (10%!).  Do NOT believe what the Sugar Association may tell you.

A few other simple rules:

  1. Eat slowly, so your hunger is satisfied before you finish the meal.  Eating fast does not give your body time to realise it has enough, and so you often overeat if you eat too fast.  Eat when relaxed, preferable in company.  Take your time, and that's easier in company than alone.  The French and southern-European habit of taking two hour lunch breaks is something we must defend!
  2. Chew food well, as you parents taught you to do.
  3. Never skip a meal:  breakfast, lunch, dinner.  Skipping meals makes your body think that the food supply is erratic, that therefore the times are probably bad and it's better to stock up on fat.
  4. Don't take second helpings;  just eat the first one slowly.
  5. Don't eat between meals, but do drink.
  6. Drink tea, coffee or just plain water.  No soft drinks, even "dietary" ones. (I never drank those anyway)
  7. Wine is fine (I have two glasses of red a day).
  8. Avoid sugar.  Eat black chocolate, not milk chocolate.
  9. Avoid salt.  Replace it with spices, e.g. pepper.  Of course you do need salt if you eat a lot of vegetables, but a good piece of meat is OK too for salt supply.
  10. Avoid certain combinations such as meats with cream sauces.  Boiled potatoes are fine, but not with cream and cheese on top.  I do eat meat with French fries, no problem, but not every day.
  11. Eat a lot of vegetables (but not with cream sauces on them, and watch out for ready-made "vinaigrette" or any other sald dressing from the bottle:  these days they often contain sugar!).
  12. Avoid processed foods.
  13. Fish is good.  Pasta with cream is not.
  14. Concentrate on the original taste of the food, soon you will enjoy it and start to hate the taste of processed foods.

I hate exercising, I never did any, so during our friendly competition I did none of it.  And I mean NO EXERCISE.  Yet I lost three kg in the first month and two in most successive months, stopping when I reached 74kg.

It's very easy to keep my weight now I'm back down to 74kg again.

However, guess what:  the Sugar Association thinks it's not sugar but lack of exercise that is to blame.  Don't believe them:  sugar is transformed into fat.

And guess another thing:  in the stores, on the shelves next to the foods with sugar added, the sugarless foods cost MORE, not less!  So if you are not very affluent, it is much more difficult to keep your weight down.  This is especially true in the US where non-processed foods are quite difficult to find or very expensive and the poorer people are almost condemned to become obese.

I repeat again:  slimming or getting fat MUST have to do with the way your metabolism works.  Any diet therefore MUST tell you how it works with your food metabolism.

A good book on how to choose your food that also explains what happens metabolically:  "Je mange donc je maigris" or in English: "Eat yourself slim" (but don't ask me what "adapted for North America" means; perhaps imperial units?)

Do exercise

Exercising is still necessary though:  slimming removes fat but also muscle, so unless you do some moderate exercising you may lose too much muscle tonus and that's not good.  But the exercise is to keep your muscles, not to lose weight.

BMI

Don't overdo dieting:  just be normal.  There is a measure, called the "index de Quételet", or the "body mass index".  This was developed by Belgian statistician Quételet  in the 19th century (nothing new under the sun...) and I find it rather surprising that in 2004 we do not have a better way of describing obesity.

I could not find any explanation of how Quételet derived his formula, but my own attempt at reconstruction of his reasoning behind it goes like this:

Think of an empty toy balloon.  It has no volume because it is flat, but it does have a surface area.  Now slowly blow it up:  as you put more air into it, the volume increases, but until the membrane gets taut, the surface area of the membrane stays the same.  You could make an index of "blown-up-ness" of the balloon by dividing the volume of air in it by the surface area of the membrane.  If it is zero, the balloon is entirely flat.  The higher the ratio, the more blown up the balloon is.  (What happens after the menbrane gets taut we do not discuss here.)

Now think of a person.  It should be the same:  you get an idea of how "blown up" you are by dividing your volume by your skin surface area.

But how to get your volume and your skin surface area?

Our density is about that of water (we nearly float, but not quite).  So our volume is proportional to our weight:  the more you weigh, the more volume you have.  So that's the first number: your volume is like your weight.

For any shape, be it a cube or a car or a person,  surface area quadruples if length doubles.   Your skin surface area is therefore roughly proportional to the square of your height, if you are of normal weight and proportions.  So there is the second number:  surface area is like the square of your height.

Therefore the ratio of volume over surface area is the same as that of weight over the square of height:  the higher this number is, the "fuller" your skin envelope is filled with your body volume. 

The Body Mass Index is the number obtained by dividing your weight (in kg) by the square of your height (in m).  It is almost the same as dividing your volume by your surface and it therefore tells you your "balloon-ness".  A good number is 20 to 25 for men and 19 to 24 for women.  Over that you are overweight, over 30 you are obese and over 40 you are seriously in danger.

I wrote a small application that shows you where you are situated in a surrounding area of weights and heights.  This is a screen shot:

It shows that a person of 1.82m weighing 76kg has a BMI of 22.9 which is well within the green zone.  You can download the application for Mac OS X for free.

Caution about BMI

While the BMI index is usable for most people, there are notable exceptions:  athletes have more muscle than average, their BMI reflects excess muscle not excess fat.  Older people have less muscle and usually more fat so even if their BMI seems OK there may still be too much fat.

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next planned revision: 2009-11