Low Fat Diets

Low Fat Diets has been a really difficult post to write. I actually started it at the beginning of December but because there is so much contradictory information out there,it is only now being released into the ether. There seems to be as many different views as there are experts out there so this is only the first of what many be several posts.

I started thinking about fats when I realised that cutting grains out of the diet means that you have to up your fat intake in order to get enough calories.

Eek, but fat’s disgusting, I thought. I’ll drop dead of a heart attack! What’s worse – a heart attack or being ill?

Butter - eek!

Butter – eek!

So I started researching and found plenty of people saying that we have been mislead about this whole fat thing. That fat is an essential part of our diet; even saturated fat is good for us.

2014 arrived and the usual wave of weight loss adverts and informative programmes on the TV.  Gym membership booms in January before starting to tail off in February as we all try to lose the festive pounds.

Predictably, a lot of the diets are based on fat reduction. More skinless chicken breast and zero fat yoghurt anyone?

From all research I have done recently, it seems as though cutting fat out of your diet is really not a good idea. We need fat to fuel our body, repair and replace cells.

We used to eat a high fat diet.  Dripping, scrape, lard and suet were all prized ingredients until the low fat craze kicked off in the 1980’s – how did that happen?

Well the low fat hypothesis seems to have its roots a good 150 years ago with a Russian scientist who discovered plaques on coronary arteries but our current preoccupation is more recent. In the 1950’s a scientist named Ancel Keys published a study which showed a correlation between the dietary fat intake and deaths from heart disease in seven countries.  The correlation was positive and strong, leading Keys to argue that a high fat intake caused heart disease.

Keys had cherry picked his data from figures supplied by 22 countries which viewed as a whole suggested a much weaker positive correlation.

Even though he had used the best data he had to argue that fat intake caused heart disease, his work was not immediately accepted by the scientific community.

His work did not gain much recognition until 1961 when he was featured on the front of Time magazine.

This coverage raised his profile and from that point on, the American Heart Association began to recommend a low fat, high carbohydrate diet.

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Despite this, it was not until 1984 when Time magazine published an article laying out the evidence for a relationship between cholesterol intake and heart disease that the low fat hypothesis was fully accepted. The cover of that magazine can be seen here.

What was not so widely reported but was known about at the time, was that is is oxidised cholesterol which is positively correlated with heart disease. Provided the blood cholesterol does not become oxidised, the association between blood cholesterol levels and heart just does not exist.

What causes cholesterol to oxidise? Well it seems as though corn oil and trans fats are probably culprits. There are also suggestions out there in the internet that sugars could play a part. Sugars have also been fingered in obesity because excess glucose in the bloodstream is swiftly removed by insulin and shuttled off to fat cells for safe storage.

As I said at the start though the picture is very confusing. Plenty of sources claim that eating cholesterol and other fats has little impact on blood cholesterol levels. Other sources suggest that the body makes the cholesterol that it needs for body maintenance and repair from the food you eat. If you need more then your body makes more. If you don’t need it then the body excretes it. Confused? Yup!

There are suggestions that the body may make more cholesterol in response to damage in the body and that blaming cholesterol for heart disease is like blaming crime on high police numbers in a rough neighbourhood (or hair dye for grey hair).

The more I read, the less convinced I become that a low fat diet is a good thing. We seem to need fat to make cholesterol to repair and maintain every cell in our bodies. Poor quality fat is not used to make cholesterol unless there is no other fat available. Possibly this accounts for the link between seed oils and oxidised cholesterol? I have yet to track the evidence down for this so don’t quote me!

What is clear is that conventional wisdom believes strongly that a low fat diet is highly desirable and that this belief can be traced back to Ancel Keys and his work that, had he not featured on the front cover of a widely read magazine, might by now be forgotten.

And then – Dear Folks – just to prove that it never rains but it pours, Twitter threw up a Daily Mail article today this all about how we have got it wrong about fat. It must be a sign!

Yummy fats.

Yummy fats.

 

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