Friend or foe? The furor over fats.

My blood pressure is up. It’s official. Not because of high cholesterol from eating fats, but from reading about them. Hotdiggedydamn, the chat about fat has got hot. Saying opinions are ‘polarised’ would be like saying Donald Trump is a bit of a plonker - understatement extraordinaire.

So who’s saying what?

The National Obesity Forum published a report claiming that government advice to cut down on fat is having “disastrous health consequences”. “The change in dietary advice to promote low-fat foods is perhaps the biggest mistake in modern medical history,” says Dr Aseem Malhotra, a senior NOF adviser.

Is he right? No, according to Public Health England’s chief nutritionist, Dr Alison Tedstone. “It’s a risk to the nation’s health when potentially influential voices suggest people should eat a high-fat diet, especially saturated fat,” she says, pointing out that official advice is based on a lot more studies than the NOF’s.

Let’s see if we can make up our own minds…

Firstly, what is fat?

Fat is a rich source of energy: 1 gram provides 37 kJ or 9 kcal. It’s made up of building blocks called ‘fatty acids’ and these are classified as saturated, monounsaturated or polyunsaturated depending on their chemical structure. All types of fat provide the same number of calories.

How much fat do we need each day?

When looking at food labels, look at the ‘per 100g’ column to judge if they contain high levels of fat:

High Total Fat = more than 17.5 g fat per 100g (colour coded red)

Medium Total Fat = 3.1g - 17.5g fat per 100g (colour coded amber)

Low Total Fat = 3.0g fat or less per 100g (colour coded green)

High Sat Fat = more than 5g of saturates per 100g

Medium Sat Fat = 1.6 - 4.9g saturates per 100g

Low Sat Fat = 1.5g or less of saturates per 100g

Are we eating too much fat?

The Department of Health recommends that fat intake should not exceed 35% of our total daily energy intake from food, and saturated fat should not exceed 11% of total energy intake from food. As a population, our total fat intake is close to these recommendations, but the amount of saturated fat we consume is considered by some to be too high.

Saturated fats:

Where can saturated fat be found?

All foods contain a mix of fats. But foods with a higher proportion of saturated fats include fatty meats, full-fat dairy products and some processed foods. Fats with a greater proportion of saturated fatty acids tend to be solid at room temperature (e.g. butter and lard) but some oils (e.g. palm and coconut oil) are also high in saturates.

Sat fats and cholesterol:

Traditionally we have been told that too much saturated fat can increase the amount of cholesterol in our blood, which increases the risk of heart disease and stroke.

There are two types of cholesterol in the body:

HDL (good) cholesterol and LDL (bad) cholesterol.

‘Bad’ cholesterol can build up in our blood vessels and cause them to narrow, increasing the risk of blood clots, which can lead to heart attacks or strokes. ‘Good’ cholesterol retrieves the ‘bad’ cholesterol from the body and carries it to the liver so that too much doesn't build up in the bloodstream. High intakes of saturated fat can increase the level of ‘bad’ cholesterol in our blood.

But this link between saturated fats and the development of cholesterol and heart disease is hotly contested. Other evidence suggests that saturated fat may not be directly linked to raised LDL cholesterol, however eating a diet high in fat can contribute to obesity, which in itself is a risk factor for heart disease.

The only types of fat that are unanimously considered to have a significant link to coronary disease are trans-fats.

A bit about trans-fats.

Trans fatty acids (or trans-fats) are produced when vegetable oils are hydrogenated. This is a chemical process that hardens the vegetable oil for their widespread use as an ingredient in frying and baking. Hydrogenated oils are used by food manufactures to improve the shelf life, taste and culinary properties of processed foods such as biscuits, cakes, pies and takeaway foods (all my favourite foods sitting together in one lovely little list). There is a small amount of naturally occurring trans-fats in dairy products, such as cheese and cream and in beef, lamb and mutton.

Concern about the health implications of consuming high intakes of trans-fats has led to changes in manufacturing practices in recent years and good progress has been made to remove them from some foods, although there has not been a complete ban.

Why avoid trans-fats?

Trans-fats have been proven to raise blood cholesterol levels, particularly levels of ‘bad’ LDL cholesterol. Trans-fats can also reduce the ‘good’ HDL cholesterol, as well as increasing levels of triglycerides - another form of blood fat. All of these effects of trans-fats can raise your risk of coronary heart disease (CHD) and dietary intake should be controlled.

Which types of fat are unanimously considered to be healthy choices?

Unsaturated fats.

All fats contain a mixture of saturated and unsaturated fatty acids.

Unsaturated fats contain a higher proportion of unsaturated fatty acids and are usually liquid at room temperature. Monounsaturated and polyunsaturated fats help to maintain healthy cholesterol levels and are found in vegetable oils such as olive, rapeseed and sunflower oils, avocados, nuts and seeds. Polyunsaturated fats provide us with essential fatty acids like omega-3 which are important for health.

Omega 3 fatty acids

These are a group of polyunsaturated fatty acids. These are found in oily fish (e.g. mackerel, salmon and sardines) and in smaller amounts in sunflower oil, flax, linseed oil and walnuts. Omega 3 fatty acids are associated with good heart health as they can help to prevent blood clotting and regulate heart rhythm.

The Ketogenic Diet:

Before I finish up, it’s worth mentioning the Ketogenic Diet…

What is it? Here’s a fairly straightforward pictorial explanation, and you’ll quickly see why it’s relevant:

People promoting the diet say it uses the body’s own fat burning system to help people lose significant weight quickly.

The whole diet is based on a process called ketosis, which is when your body is so depleted of carbs that your liver converts fat into fatty acids and ketone bodies, which can be used as energy.

The ketones replace carbohydrates as your body’s main energy source, meaning you are running on (and burning) fat.

Once again, the proponents and the adversaries all have their arguments. I’m firmly in the Coomber camp on this one:

“Everything in the world of health, fitness and supplementation needs to come down to context. Does it feed your needs, your goals, and your lifestyle? The Ketogenic Diet is a very restrictive diet, eating a diet very heavy in fat is hard, it's tough to eat out, tough to eat on the fly, it's very unforgiving, you’re either on it 100% or you’re not.

Now most people do the Ketogenic Diet as they think there is some benefit to fat loss, be ketogenic and you'll burn MORE fat, or you won't have to count calories / exercise portion control, your body will just burn fat as you’re eating fat. You turn yourself into a fat burning machine! But the reality is you need to eat less than you burn to lose weight. So such a restrictive diet isn't needed. Instead, keep your diet varied, balanced, and healthy, and most of all, keep the enjoyment in it.” Well said.

Conclusions:

So is there any kind of conclusion or are we stuck between a rock and a lard place?! (Can barely type, am so busy laughing at my own joke and performing self-congratulatory back pats).

Clearly, the effects of fat – and importantly, different kinds of fats – are strongly contested. The current furore demonstrates, if nothing else, how passionate the debate over nutrition can be and how difficult it is to reach any sort of simple truth.

Everybody agrees that trans-fats are bad and they have been banned or phased out in many countries. Everyone agrees that olive and seed oils – also fats – are good. But in the middle are saturated fats.

So, sticking with the middle ground, the only real question I want answered in this conclusion is: can I jam my head into a bucket of doughnuts dripping in fat or not?

Answer: Maybe. Sometimes.

References and quotations:

British Nutrition Foundation.

The Guardian

Ben Coomber

BBC Good Food

Women’s Health

Disclaimer:

I am not a dietician or a nutritionist, and make no claims to the contrary. What is written on this site should not be taken as fact or advice. It is merely an opinion blog.