Should you follow a low-fat diet? Or a high fat diet? Which fats are healthy? Which fats should you avoid? The list of questions regarding fats in the diet is endless. Thanks to the low-fat diet era of the 80s there is much confusion around whether foods that contain fats are healthy or not. So, what’s the story with fats? Should you include fat in your diet and if so how?

What types of fats are there, and which ones are considered healthy?

Fats in foods are generally referred to as being either ‘healthy’ (unsaturated) or ‘unhealthy’ (saturated/trans), however how do you know which fats are which? Generally, healthy fats tend to be liquid at room temperature such as extra virgin olive oil, while unhealthy fats tend to be solid at room temperature such as the fat from sausages.

Unsaturated fats

Unsaturated fats are considered ‘healthy’ fats and are an important part of a healthy diet, providing us with essential fatty acids, helping with the absorption of fat-soluble vitamins and assisting with improving cholesterol levels. There are two types of unsaturated fats:

  • Monounsaturated fats which are found in:
    • Avocadoes
    • Olives and extra virgin olive oil
    • Peanuts
    • Nuts such as almonds, cashews, hazelnuts, pistachios


  • Polyunsaturated fats, also referred to omega-3 and omega-6 fats:
  • Long chain omega 3 fats (EPA, DHA, DPA)are found mainly in marine sources such as fish and seafood such as salmon and sardines.
  • Short chain omega 3 fats (ALA)are found mainly in plant-based sources such as flaxseeds (linseeds) and walnuts.
  • Omega 6 fats are found in a range of vegetable oils, such as safflower and sunflower oil, and sunflower seeds.


Saturated and trans fats

Fats that are considered unhealthy are saturated fats and trans fats. These fats have been associated with an increased risk of heart disease through their influence on raising bad cholesterol levels (LDL) and lowering good cholesterol (HDL).

  • Saturated fats are found predominantly in animal foods such as red meat, salami, bacon, milk, butter and cheese. They are also found in coconut products such as coconut oil, and palm oil.
  • Trans fats are found predominantly in ultra-processed foods as they are a product of the large-scale manufacturing processes such as baking and frying. Trans fats are also found in small amounts naturally in some animal foods.


A note on saturated fats

Now you may have heard that saturated fats are healthy, not unhealthy, with lots of information online claiming this. A lot of this debate and confusion comes from the fact that there isn’t just one type of saturated fat, in fact there are many different types of saturated fats. Each of these types of saturated fats have slightly different chemical structures and it is these small differences that mean they may act slightly differently in the body. This is why some people say coconut oil isn’t unhealthy even though it contains saturated fats. Coconut oil contains medium-chain triglycerides which are metabolised by the body in a different way to long chain triglycerides which are another type of saturated fat found in other foods. Because of this difference in metabolism, claims are made about coconut oil being a healthy fat. But despite these differences, it seems the saturated fats in coconut oil do tend to have some cholesterol raising properties, though perhaps not as much as other saturated fats, and so more research needs to be done to fully understand any differences.  


Should I include healthy fats in my diet?

 Yes absolutely! We have moved past the low-fat diet era and now recommend including healthy fats each day. There is no need to follow a no/low fat diet (unless medically indicated). Yes, fats are more energy dense than other macronutrients and so having a high fat diet can provide a lot of calories which can contribute to weight gain (but yes weight is much more than just calories in/out… but that is a blog for another time). So, what we want to aim for is a small amount of healthy fats each day to provide the health benefits but not the calories. This could look like:

  • 30g of nuts a day (a handful)
  • 1 tablespoon of avocado on a sandwich
  • 2 tablespoons of extra virgin olive oil spread across the day