The Truth About Dietary Fats: The Good, The Bad And The Indifferent

salmon and avocado flickrDespite what you may have heard, fat is an essential part of a healthy balanced diet and has many important functions in the body. Apart from being a valuable source of energy, it also helps you absorb certain vitamins and minerals, it’s needed to build cell membranes and the sheaths surrounding nerves, it’s essential to blood clotting, it’s required for the manufacture of certain hormones and it’s vital to the health of your skin, joints, muscles, and much more.

And on top of all that having sufficient fat in your diet is essential for optimal muscle growth as well.

Fats are made up of fatty acids attached to a glycerol molecule. And fatty acids are basically chains of carbon atoms with hydrogen atoms attached to them. But some fats are more beneficial than others of course; so in this article I’ll describe the four different types of dietary fat – the good fats, the bad fats and those that fall somewhere in between.

Trans Fats

These are artificial fats that are made by heating polyunsaturated vegetable oils to high temperatures with hydrogen and a metal catalyst (a process known as hydrogenation). This turns the liquid oil into a solid, and it also increases its shelf life.

Trans fats are found in many margarine’s, shortening and most processed and fast foods, including crisps, cookies, doughnuts, various pastries and fried foods, and they have been shown to raise bad (LDL) cholesterol, lower good (HDL) cholesterol and greatly increase your risk of heart disease, stroke, type 2 diabetes and many other diseases.

Trans fats are about the worst thing you could possibly eat and should be kept to an absolute minimum in your diet, if not avoided completely.

The problem with trying to avoid trans fats however is that if a food contains less than 0.5g of trans fat per serving it is allowed to be labelled as zero trans fat. So always check the ingredients list and if you see the words “hydrogenated” or “partially hydrogenated” vegetable oil on there you will know it contains trans fats and should be avoided.

Saturated Fats

Saturated fats contain a full quota of hydrogen atoms attached to their carbon atoms, so they are “saturated” with hydrogen, and because of this they contain no double bonds between their carbon atoms.

Saturated fats are found in many animal foods such as meat, lard, full fat milk and cheese, butter, cream and eggs, as well as in coconuts and coconut oil. These fats are very resistant to heat (which makes them ideal for cooking with) and they are generally solid at room temperature.

Saturated fats have had a particularly bad rap over the years as it is claimed they increase cholesterol levels and give us heart attacks. But the real picture is a little more complicated than that. It’s true that saturated fats do tend to increase blood cholesterol levels, but they increase both HDL (good) and LDL (bad) cholesterol. And as HDL exerts a protective effect against heart disease, this isn’t as bad as was once supposed.

Add to this the fact that there are two sub types of LDL – small dense LDL (which easily penetrates your blood vessel walls and causes cardiovascular disease) and large fluffy LDL (which doesn’t penetrate blood vessel walls so easily and is fairly benign). And eating saturated fat can actually change small dense LDL particles into large fluffy particles.

So saturated fats are not as bad as was first thought, and eating them in moderation is unlikely to increase your risk of heart disease, especially if you eat a generally healthy diet and exercise regularly. Also there are several different types of saturated fats, and not all of them cause an increase in LDL anyway. And some types, notably the medium chain triglycerides found in coconut oil, are actually beneficial and help protect against heart disease.

So there’s no need to limit your consumption of such excellent muscle building foods as red meat and eggs as the saturated fat in them should not be a problem. Besides which an increase in saturated fat consumption is associated with an increase in testosterone production, especially when combined with resistance training.

Monounsaturated Fats

Monounsaturated fats contain one double bond in their carbon chains, which means they have two fewer hydrogen atoms than saturated fats, and they have a bend at the double bond. This structure keeps them liquid at room temperature.

Monounsaturated fats are found in foods such as nuts, seeds, avocados and olive oil. These are good healthy fats as they help lower LDL levels and reduce your risk of heart disease and stroke.

Polyunsaturated Fats

These are the essential fats; that is they are needed for normal body function, but your body can’t make them itself, so you have to get them from food. Polyunsaturated fats have two or more double bonds in their carbon chains, so they have fewer hydrogen atoms than either monounsaturated fats or saturated fats. And again they are liquid at room temperature.

There are two main types of polyunsaturated fats – omega-3 and omega-6 fats. The numbers refer to the distance between the beginning of the carbon chain and the first double bond. And both of these types of fat confer health benefits.

Good sources of omega-3 fatty acids include oily fish (e.g. salmon, mackerel and sardines), flax seeds and walnuts. These are the healthiest of all the fats, and possibly the closest thing there is to a real miracle food. They help protect against heart disease and stroke by normalizing blood pressure, increasing HDL levels and lowering triglycerides. But they have many more health benefits on top of this, such as helping to improve brain function, joint health, skin condition, immunity and much more.

And on top of this omega-3 fatty acids can help you build muscle and burn fat too.

Omega-6 fatty acids are found in most vegetable oils and various types of nuts. And these have also been linked to a reduced risk of cardiovascular disease.

But the problem with the typical British and American diet is that it tends to contain far too much omega-6 fats and not nearly enough omega-3 fats. And this imbalance contributes to increased inflammation and disease in the body. So although omega-6 fats are essential fats and good for your health in moderation, most people need to reduce the amount they are consuming and consume more omega-3 fats, either by eating more oily fish or by taking an omega-3 fish oil supplement.

How Much Fat Should You Eat Per Day?

So now you have a basic understanding of the four types of fat and why fat is such an important part of a healthy diet. But just how much fat should you be eating each day? Well the usual recommendation is that 20 – 35% of your daily calorie intake should come from fat.

To make sense of that you need to know that fat contains 9 calories per gram (whereas protein and carbohydrates both contain 4 calories per gram). So if you are eating 2500 calories per day you’ll want between 500 and 875 of those calories to come from fat, which means you should be consuming 55 – 97g of fat per day.

Most of this should come from healthy monounsaturated and polyunsaturated fats, with a particular emphasis on getting plenty of omega-3 fatty acids. And the rest will obviously come from saturated fats.

So that’s the truth about fats. Thanks for reading, and if you enjoyed this article do share it so that others can benefit too.

Photo credit: Laurel F, CC BY-SA 2.0, via Flickr

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