How to use Science to Lose Weight #2 – carbohydrates

So your body runs on glucose. Glucose belongs to a class of chemicals called carbohydrates. And before we go any further we must look at what carbohydrates are and how they work.

Carbohydrates are very sensibly named – as their most basic structure is carbon + water. That is, their basic formula is CH2O, and every carbohydrate has this basic formula, but only in multiples of 6. So glucose is C6H12O6.

Image result for glucose

This 6 – carbon unit is the most basic structure possible, so it is referred to as a monosaccharide.

Table sugar (sucrose) is C12H24O12 and looks like this:

Image result for sucrose

So sucrose is a disaccharide, and is composed of two monosaccharides.

And the sky’s the limit – saccharide units can be added together to infinity, like chemical lego blocks. An example of a polysaccharide is starch:

Image result for starch

So a complex carbohydrate like starch is made up of many glucose units. Before your body gets fuel, therefore, it must break these complex molecules into its component glucose molecules.

But the real question is – how quickly does this happen? If the breakdown happens quickly, then your blood is flooded with glucose.  This can cause a serious medical condition called hyperglycemia, so your body removes the excess glucose by releasing insulin into your blood from your pancreas.

This has two long-term effects – firstly it causes you to put on weight, as the excess sugar is converted to fat. But it can also cause you to become a diabetic, as your pancreas eventually gets overloaded and just gives up – this is why fat people are often also diabetic.

The rate at which a food releases glucose is referred to as its glycemic index (GI), and is the single most important factor in determining whether the food is fattening or not.

Now, this results in some weird outcomes. For example, look on the label for Nutella and you’ll see it’s loaded with sugar and fat – but it’s low in GI. And the reason is simply that the fat slows down the rate at which the sugar breaks down.

And this is a pattern – often the fibre in something slows down the sugar absorption rate, so you are far better, for example, eating whole fruits rather than fruit juices.

For further reading, have a look at Eat Yourself Slim, which explains all this in fine detail

How to use Science to Lose Weight #1

The human body is the most complex chemical reactor in existence. Ultimately, the amount of fat on your body is the result of multiple factors, many of which are poorly understood in the marketplace.

The purpose of this series of posts is to explain what those factors are, so you can make informed lifestyle decisions decisions when choosing how and when you exercise, and what type of food you eat

This has been a particular issue for me for many years now, as I am one of the small number of men to have suffered from an eating disorder. Eating disorders are almost exclusively the domain of women (97%). I am one of the 3%.

If you are reading this article to quickly get to the bottom line (as I often do) I will very quickly summarise the conclusions I have come to, and the rest of this article and the ones that follow it will explain the logic behind those conclusions

In summary:

1. The concept of calories in, calories out is wrong. The number of calories a food contains doesn’t mean much,

2. The glycaemic index of a food is everything.

3. When looking at a food label the amount of sugar a food contains is far more important than the amount of fat it contains.

4. When selecting foods based upon the type of fat they contain, where possible consume monounsaturated fats.

The first issue to is how the body gets its energy to operate. In other words, where does the body get its fuel? Your car gets its energy from either petrol or diesel – what is the fuel that your body runs on?

The answer is that it is mostly glycogen (a form of glucose). I say “mostly” because under some circumstances the body has the ability to switch to different fuels, but for the purpose of this discussion we can stick with glucose as the main source of fuel.

In simple terms there are two main of glucose – carbohydrates and fat in extreme circumstances muscle tissue can be broken down to provide glucose, but this is not the normal mechanism of operation.
In my next post we’ll consider this fuel system in more detail, and start to understand how we can manage it to control our waistlines.

Is Julian Cribb Right?

Last week, during Dr Karl’s segment on 720 ABC radio in Perth, he had a guest by the name of Julian Cribb, who has recently written a book entitled “poison planet”. This book follows up other books with such cheery titles as “The Coming Famine” and “White Death.”

I had never heard of him before last Thursday, but he apparently passes himself off as a “science writer.” When I looked into it, all I could come up with is that he is a journalist, with no mention of any scientific qualifications.

I sent him an email to find out what his qualifications were, but have not as yet received a reply.

Anyhow, over the space of a few minutes on 720 last Thursday he managed to imply that anyone who breastfed babies was giving them “a mouthful of pesticides” and that we shouldn’t use plastic baby bottles as they contain toxic chemicals.

By the end of the show panicked mothers were texting in to ask whether they could use stainless steel bottles to feed their babies, and one mother said “thanks for making me feel like I’m poisoning my baby.”

Let’s look at these two claims and see what the science says.

The use of pesticides in Australia is controlled by the APVMA (Australian Pesticides and Veterinary Medicine Association). Essentially, it is impossible to use a pesticide in Australia without a licence from the APVMA.

This applies to the cans of fly sprays that you buy from the supermarket, commercial pest controllers, and also fruit growers.

Most people don’t know this – they think that fruit growers have open slather to spray whatever the hell they want onto their crops as often as they want, just so long as the fruit gets to market intact. But the very opposite is the case.

They must apply to the APVMA for a licence for any pesticide they wish to use. And this licence does not just refer to the particular chemical, but to every aspect of the procedure. That is, they must specify the exact concentration of chemical used, the coverage rate (litres sprayed per acre), spraying frequency, and withholding period. The withholding period refers to the time period between the last spray and the arrival of the fruit on the supermarket shelves.

Growers must keep a log of their spraying schedule, as it is subject to inspection at any time. And on top of all this, inspectors go to the markets where they take fruit directly off the trucks, and take them to a lab for testing. Any occasions where the level of pesticides on fruit is above the guidelines results in hefty fines.

So can the APVMA be trusted?

Well, it depends who you talk to. Fruit growers see them as the Gestapo, because their extremely conservative approach places a great burden, both practically and in terms of the regulatory requirements on them.

And they are certainly conservative. The amount of pesticide that they allow to be sprayed, or to remain on fruits, has safety factors upon safety factors upon safety factors. For for example, one of the measurements they use is the NOEL (No Observable Effect Limit).

This is a clinical number which tells you what level of a chemical you can have in your bloodstream before any effect whatsoever is observed, no matter how minor. To give you an idea of how conservative the APVMA is, they take this number and divide it by 10. This is a bit like saying that the best way to make sure you don’t get a speeding ticket in a 60 km/h zone is to go no faster than 6 km/h.

And there are other safety factors as well. But from the consumer’s point of view, you can have absolute confidence that none of the fruit that you get off the shelves has anywhere near enough insecticide to remotely approach a level where it could have any possible tiny effect on your health. As a matter of fact when they take the fruit for testing, most results come back as being below the level of detection of the extremely sophisticated insensitive analytical instruments that are used.

And part of this is the actual chemicals that are used. Years ago, chemicals like DDT were popular for the simple reason that they were stable – that is, they didn’t degrade in the environment. The shoe he is now completely on the other foot, and all pesticides used these days are biodegradable – that is, they degrade quickly when exposed to air or sunlight.

So the bottom line is this – Julian Cribb is completely wrong. Under the present regulations, there is just no possible way that any person could ingest pesticides off fruit that they eat to harm either themselves or their children.

The other claim he made was about plastics, and that they are unsafe for children. The implication, I suppose, is that being petrochemical products, these products are inherently evil, as we all know that oil companies are evil.

Again, this does not stack up. The only chemical that has been raised as a concern in plastic bottles or plates is bisphenol A (BPA). In sufficiently high levels, this chemical can act as an artificial hormone, which is similar to the mechanism of DDT.

Many studies buy both American and European food safety authorities, however, have determined that in the levels that BPA finds its way into food, there is simply no argument to suggest that it is a health hazard.

This, however, does not stop people who market baby products selling plastics that are “BPA free”, so if you want to be really, really, really sure, you simply buy these.

The other thing you can do is to look on the bottom of the item, where there will be a little triangle with a number in it. This is a recycling code that recyclers use to sort products into the right categories. The only classes of plastics that could even possibly contain BPA are those in categories 3 (PVC) and 7 (polycarbonate), so if you just avoid these, then you have eliminated even the possibility of your children consuming any BPA.

So if you threw out all your plastic bottles after listening to the show last Thursday, rush out to the SULO and retrieve them. Actually, don’t – buy new ones.

One warning about plastics, however – make sure they are microwave safe before you blast them. If in doubt, put the empty vessel into the microwave and zap it. If it gets hot, it’s not microwave safe.

The Chemistry of Weight Loss #2: Our body’s fuel system

Yesterday we looked at the chemistry of fat. Elsewhere, we have looked at the chemistry of carbohydrates

So which one does our body use?

Our body is a complex reactor which is capable of converting  fuel into energy. rather like our car. If we want our car to run, we have to put the right fuel in.  If we have apetrol car  and we put diesel in, for example,  it won’t run.

In just the  same way,  how body has a fuel system . Now it’s not quiet  as simple as that ,as our body  actually has several fuel  systems ,but there is one major  system that  dominates all others  that will look  at  today.  Essentially, our  body runs on  glycogen .

Glycogen is the  simplest  carbohydrate , and is what any complex carbohydrate must be broken  down  into  in order to act as a fuel . As I have discussed elsewhere,  if the glycogen is coming from  complex carbohydrates, then  this is a simple  process,  as simple as breaking a Lego  structure  into individual blocks. This process  can happen quickly  and it is the fuel that  our body uses most of the time,  particularly when doing anything at  all energetic.

Under sustained periods of exercise ,if how  body runs out of  complex carbohydrate,  it runs out of glycogen ,and this process is called going  “to the wall “. This is something experienced by marathon on runners for example.  And it’s the kind of thing  you experience if you skip  breakfast and lead a  busy morning.  By the time lunch rolls round,  you are very lethargic.

So the  lesson is,  that most of the time we are running on  glycogen.

This means that if we run out  of complex carbohydrate , our body must manufacture glycogen from somewhere else , and this is where it becomes complex,  and also represents ana opportunity for  weight loss.


The Chemistry of Weight Loss #1: The chemistry of fat.

We’re a nation of fatties – well at least that’s the popular view. Weight loss programs are scattered across the internet, TV, and (women’s) magazines.

So who do you believe? Which programs and/or diets work, and why?

Well, it’s not too hard to understand, if we go back to basics and look at the chemical reactions that occur in our body, what fat is, how it is made, and how it is removed. Like most things in life, there is a chemical explanation.

The first point to understand is that your body is an incredibly sophisticated chemical reactor that is able to convert very different chemicals into each other, with an efficiency and specificity that would be impossible in any laboratory. No industrial process in even the most sophisticated pharmacalogical facility in the world would be capable of carrying out the sophisticated and complex chemical reactions that our body does every day, silent and unseen.

Lets start by looking at the chemistry of fat. Essentially any animal or vegetable fat is a triglyceride, which is basically shaped like an E:

Three fatty acid chains are connected to a glycerol backbone, hence the name. Note that the 3 fatty acid chains are all straight, with the carbon atoms linked by single bonds. We call this a saturated fat because you can’t fit any more hydrogens on it.

Contrast that structure with this:

The third fatty acid chain has a double bond (in green). This molecule is no longer saturated, as there is room for two more hydrogens. That is, two hydrogens could be added across this bond, to convert it to a single bond and make it look like the molecule in the upper image. So because it is not saturated, we say it is unsaturated. Specifically, it is monounsaturated, as there is one double bond.

If there is more than one double bond, it is said to be polyunsaturated.

Now, you will note that the carbon chain with the double bond is bent. The implications of this is that the molecules will not stack together very well on top of each other, in just the same way that regular shaped boxes will stack together easier than irregular shaped boxes.

This means that monounsaturated triglycerides are generally liquid (like olive oil) and saturated fats (like lard) are solid at room temperature.

Stay tuned