Thursday, 18 June 2009

"Nutrition Organisations Talk Doodoo" Shocker

Well folks, you'll notice from my recent output that I am on my soap box at the moment. The latest story to get under my skin is this one on the BBC site, which you can read in full here.

It turns out that nutritionists have worked out the secret to losing weight. You see, "consuming foods high in water could be the key to losing weight". And the reason for this is that they "appear to keep you feeling fuller for longer. "

The Emperor's new clothes getting an airing as you will see. Half way down the article we get this gem:

  • "You need to control the portion sizes of these foods and eat them alongside lots of lower energy density foods," says Bridget Benelam, a nutrition scientist at the BNF"
Control portion size! Erm, you mean "Eat less" Ms Benelam, don't you? As for dessert:

  • "...go for mixed berries with low fat yogurt, crunchy oat cereal and honey."
Low fat yogurt? Low fat? A meal with a low level of one substance that is know to improve satiety? Baise moi!

Now do you REALLY think that your body, that sophisticated machine with a couple of million years of evolution behind it, can be fooled in such a simple way? Do you think that your body is unaware of falling energy reserves?

Energy is your body's reason d'etre. It works hard to manage your energy system and has developed several hormonal responses to manage this system. A simple energy in vs energy out model falls far short of how the body actually works to store fat.

Hotel
I was trying to think of a suitable analogy to how fat is stored - and here goes....if you imagine a hotel with 50 rooms, each with its own en suite bath and basin. Now imagine you measure the water pressure on the top floor and it is 2 bars and all the baths and basins are empty and the taps are all turned off and the plugs are not in place. The analogy I will use is of these basins and baths being 'fat stores'.

If you apply the British Dietetic Association (BDA) and British Nutrition Foundation's (BNF) understanding of obesity to this analogy, if you were to increase the pressure to 3 bar, they would conclude that as there was more water in the system (increasing the pressure), the basins and baths must therefore be full of water.

Crackers isn't it?

One of their members might actually suggest that this is nonsense. They might go on to question "what about the taps - the basins and baths will not fill up because the taps are turned off". Bingo. Our switched-on member of the BDA/BNF has correctly identified the physical mechanism stopping water going in to the basins and baths. The body's biochemical equivalent is alpha-glycerol phosphate (g-3-p).

Alpha-glycerol phosphate bonds with free fatty acids and allows them to be stored as a triglyceride. No alpha-glycerol phosphate, no triglyceride, no fat storage! We should also mention insulin. Insulin is a master hormone that transports glucose to the fat sells for storage.

The body's principle source of alpha glycerol phosphate is dietary carbohydrate - think tap fully on. Without carbohydrate, we at best get a dripping tap (g-3-p produced by glyceroneogenesis).

But now we understand the physical mechanism controlling water getting in to the baths and basins, what about emptying them?

Again there is a physical barrier, the plug. And so it is with fat storage. With elevated insulin in your body, you cannot pull the plug (OK I admit my analogy gets harder to apply here). But the take-home message is that with the body, insulin shuttles glucose to your fat cells. So if your body is busy 'shuttling' at the hormonal level, how are you going to 'unshuttle' at the same time given the same hormonal conditions ( - imagine the pipework trying to allow a two way flow of water)? You aren't.

At a biochmeical level, fat can flow in and out of the the fat cell walls unless it combines with an molecule of alpha-glycerol 3 phosphate making a triglyceride (esterification) - which, unlike a fatty acid, is too large to transit the wall of the fat cell. This is the priciple of fat storage.

No comments: