Hallelujah! The low-fat revolution seems like it’s coming to an end. Although there are plenty of people who have been aware for a long time that low fat diets are not healthy, or even beneficial for weight loss, this has only recently been talked about in the media. A scientific paper from 2010 reviewed previous studies which lead to the association between saturated fat and heart disease, and concluded that there actually is no evidence after all! Click on the link for the actual study if you are interested. AJCN Sat Fat and Heart Disease So does this mean I can go nuts with the butter? Well no, excessive intake of any type of food – including foods high in saturated fats – would be unproductive. But I really want to spread the word that very low fat diets are unhealthy, in part because for years I was sucked into the myth and pretty much felt miserable most of the time I was on them (tired, dry skin, headaches, moody.... in general, a bit of a pain in the arse to be around quite frankly). However, before you tuck into that greasy doughnut, you need to realise that not all fats are created equal and the trick is knowing which ones to go for the majority of the time (the odd treat is still not going to kill you). So here is some science for you.
Fats and oils are really one and the same thing, but “fats” is a term used to describe those that are solid at room temperature and “oils” tends to be used for fats that are liquid at room temperature. In addition, they can be broken down into categories depending on the degree of “saturation” – a chemical term used to describe the fundamental structure. Most sources of fat in the diet have a combination of both saturated and unsaturated fatty acids, but usually one predominates. Solid fats are usually comprised of mostly saturated fats. They are more stable and less easy to damage. Oils are predominantly unsaturated fats (both mono and poly- unsaturated) and are much more unstable. The degree to which a fat is damaged or spoiled is very important, as damaged fats can create havoc in the body. The quickest way to cause damage to oils is via heat, air and light. Before we get into the different types of fats in the diet, let’s firstly look at the important roles they play in the body.
- Cell structure and function
- Absorption of fat soluble vitamins
- Nerve function
- Maintaining healthy skin and hair
- Brain health
- Insulating body organs against shock
- Energy source
- Maintaining body temperature
- Adds to flavour and texture of food
- Makes meals more satisfying and filling
Before we get into the different types of fats, for those of you in a panic about cholesterol, have a look at a post I wrote on the facts and myths surrounding cholesterol.
The main sources of saturated fats are meat, dairy, eggs, coconut oil and palm oil. Small amounts of saturated fat can be part of a healthy diet, and contribute to the health benefits listed above. Coconut oil is excellent for cooking and frying. Unlike olive oil, it’s very stable and isn’t damaged when heated at high temperatures, so for this reason is preferable to use in cooking. You can find coconut oil in whole food shops and supermarkets, but don't go for the cheap stuff, it really isn't good quality. I gave it a go this summer as I was tempted by the £3 lure, but during the really hot days it melted and then when I smelled it I realised it was actually pretty rancid - Nice! So yes, I'd definitely advocate getting organic, extra virgin jars that are usually at least £6, but a little goes a long way.
In terms of dairy, go for good quality, full fat, organic produce. When buying meat, look for organic, free range meat from grass fed, rather than grain fed, animals. This is not only due to ethical reasons, but also because this meat will contain higher levels of nutrients, in particular omega-3 fatty acids, which as you will see below is a good thing. As organic meat really can be more expensive, have it less often, and increase other sources of protein, such as eggs.
Unsaturated fats – monounsaturated fatty acids
Monounsaturated fats and polyunsaturated fats are two types of unsaturated fatty acids. They are derived from vegetables and plants. Monounsaturated fats are liquid at room temperature but begin to solidify at cold temperatures. This type of fat can be found in olives and olive oil, canola oil, flaxseed oil, sesame oil, walnut and hemp oil, sunflower oil and also avocados and all nuts and seeds. It’s important not to heat them to high temperatures (such as frying), and to keep bottles sealed in cool, dark places. Go for oils that are cold pressed, extra virgin and kept in dark bottles. Use monounsaturated fats in moderation, and either only use them cold, or add at the very end of cooking, in order to lessen any damage to the oils.
Unsaturated fats – polyunsaturated fatty acids
Whilst the body is able to make saturated and mono-unsaturated fats, there are some fatty acids that are essential – meaning they cannot be produced in the body and therefore need to be obtained from our diet. These essential fats are omega-3 and omega-6 fatty acids. They support many aspects of our health, including blood pressure, brain function and lowering inflammation. These health benefits are derived from the balance between the two fatty acids. Originally it is thought our ancestors consumed a diet that was almost equal in terms of omega-3 and 6 intakes. Nowadays, we eat a diet that is extremely high in omega-6 fatty acids and low in omega-3. The ratio is thought to be somewhere around 20 to one, in favour of omega-6. In part this is due to the move away from saturated fats to “healthy” vegetable and seed oils such as sunflower oil, which is one of the main sources of omega-6 fatty acids. This skewing towards the omega-6 pathway leads to inflammatory responses, poor blood sugar control, and cardiovascular disease.
What keeps the effects of the omega-6 pathway under control? Omega-3 fatty acids. This is why increasing our intake of omega-3 and reducing our intake of omega-6 is one of the best things we can do for our health. By far the best source of omega-3 are oily fish (salmon, mackerel, herring, sardines and anchovies), ground flax seed, chia seeds, walnuts and eggs also contain omega-3, but not in nearly such large quantities. Three portions of oily fish a week is an excellent addition to the diet.
A word about trans fats
Trans fats are actually a form of unsaturated fat that have been heated to high temperatures to keep them more stable and extend their shelf life. You’ll find them in margarine and butter spreads, biscuits, cakes, fried foods and takeaways. The problem is, they are unnatural to the body, and not easily broken down. They become incorporated into the cell structure and can be extremely damaging, having clear links to cardiovascular disease, diabetes and immune dysfunction. The tide is turning against trans fats. The World Health Organisation declared them toxic but despite a number of European countries banning their use altogether, and various regulatory bodies in the U.K recommending we do the same, the government is lagging behind. Some supermarkets, such as M & S, Waitrose and the Co-op, declare all their own brands to be trans fat free, but I'd still be on the safe side an avoid the most obvious culprits such as low-fat butter spreads and margarine. Just go for good quality butter!
Ok, so I hope that wasn't too much information in one go. But sorting out what fats to include in your diet and what to avoid is such a fundamental part of healthy eating, so hopefully you can refer back to this blog to help make those important changes. Have fun!