Fats: The good, the bad and the ugly
All fats are bad for us, right? Wrong.
We all need some fats in our diet. They are a great source of energy and help us to feel full, but perhaps more importantly they help us to absorb fat soluble vitamins (vitamins A, D, E and K) and provide us with essential fatty acids which are important for brain and heart health.
The difference is that not all fats are created equal. There are two main groups when it comes to fats; saturated fats and unsaturated fats. ‘Saturated’ and ‘unsaturated’ merely describes how the molecules in the fats are joined together but the important thing to understand is how these different types of fats impact on our health.
Saturated fats are usually solid at room temperature and are thought to be less healthy for us as they can raise our cholesterol levels and increase our risk of heart disease. They are generally found in animal products such as the fat on meat and full fat dairy products e.g. butter, milk and cheese. You may have seen some controversy in the media over saturated fats and their relationship with heart disease so look out for my future post on this topic to help you debunk the myths!
Similarly to saturated fats, Trans fats also affect our cholesterol levels and increase our risk of heart disease. Artificial trans fats (i.e. not those which naturally occur in some foods) are unsaturated fats (vegetable oils) which have been processed to make them hard. A recent study found that artificial trans fats were associated with a 34% increase in death, and a 21% increase in heart disease! Trans fats can be found in processed foods such as cakes, biscuits and pastries, but spotting them on food labels can be tricky so look out for the words ‘partially hydrogenated oils’ and keep these to a minimum.
Unsaturated fats can be classified as either monounsaturated fats or polyunsaturated fats.
Monounsaturated fats are particularly good for us as they increase the good type of cholesterol (known as HDL) in our blood. Monounsaturated fats are generally found in plant foods such as nuts, olive oil and avocados.
Polyunsaturated fats are also found in plant foods such as nuts, seeds, sunflower oil and spreads, but can also be found in oily fish. Some polyunsaturated fats are ‘essential fats’ meaning that your body can’t make them so we have to get them from the diet. These include omega 3 and omega 6 fatty acids. Eating polyunsaturated fats in place of saturated fats can help to reduce the bad type of cholesterol (known as LDL) in your blood.
Good sources of omega 3s include oily fish such as salmon, mackerel and sardines, and also walnuts and flaxseeds.
Good sources of omega 6s include vegetable oils such as sunflower, safflower, walnut and corn oils.
This information is all well and good, however, we do not eat macronutrients (carbohydrates, fats, proteins) alone or even individual food items, we eat meals! So really we need to look at the bigger picture. If we substitute the saturated fat in our diet for loads of highly processed carbs we will not see any positive health effects, and in fact we could increase our overall risk of heart disease. Instead we should be substituting the saturated fats with polyunsaturated fats. So here are my top 5 tips for how we should approach fat in our diet.
- Do not be afraid of fat! A healthy balanced diet should include plenty of fats, especially the mono- and polyunsaturated varieties. So, go ahead and sprinkle some walnuts and pumpkin seeds on your porridge, tuck into that avocado at lunchtime, and drizzle some of your favourite olive oil based vinaigrette over your salad or stir through your pasta.
- Eat two portions of fish a week and ensure you are getting your omega 3’s by choosing at least one of these portions to be an oily fish. Oily fish include fish such as salmon, fresh tuna, mackerel and sardines.
- Reduce your intake of trans fats. These are commonly found in biscuits, cakes and pastries so watch out for partially hydrogenated oils on food labels.
- Swap foods high in saturated fats for those high in unsaturated fats.
Rapeseed oil is lower in saturated fat than other oils and is high in monounsaturared fat. It also contains omega 3 fatty acids and is therefore a good choice for an everyday cooking oil for good heart health. Look out for vegetable oil in the supermarket as rapeseed oil is often labelled as vegetable oil in the UK. Another good choice is sunflower oil which is again low in saturated fat but is high in polyunsaturated fats. For salad dressings/dips etc you may wish to use olive oil as it adds a tasty flavour and is high in unsaturated fats.
- Watch your intake if you are trying to lose weight. Fats are an excellent source of energy. They contain 9kcal/g, compared with protein and carbohydrates which contain just 4kcal/g. For this reason, if you are trying to lose weight it is advisable to reduce your calorie intake overall so go easy on the fats, especially trans fats. One way to do this is to choose healthy cooking methods such as grilling, boiling and steaming. When you do require an oil or fat for cooking, because let’s face it we all need the occasional roast potato in our life, opt for a vegetable oil and use a spray bottle to limit the amount of oil that you put on your food.
*References available upon request