Is Dietary Fat Healthy?

Feb 2019

You may have read in the media or heard on the news that a report published by the National Obesity Forum in association with Public Health Collaboration has been published. It states, rather topically, that low-fat foods have had ‘disastrous health consequences’ and the public health guidelines on consuming a low-fat, high carbohydrate diet should be reversed.

This opinion piece has since been heavily criticized by other experts, who say that the report has misquoted evidence and merely cherry-picked information that supported their argument. Without far deeper analysis, no conclusions can be rightfully drawn from the report.

Is dietary fat healthy article
So who has got it right?

Firstly, it is very difficult indeed to carry out good, quality nutritional research. That is because everyone is unique: our genetics, our environmental determinators, our physical activity levels, job, family, work, finances, social norms and much, much more, have a huge impact on both the nutrition choices we make and the impact these choices have on us, in both the short and long term. The act of drawing general conclusions from large population studies and then attempting to apply results to an individual is always going to be tricky, as only a small minority of us will ever hover around the perfect statistical average! Neither side is necessarily therefore 100% ‘right’ or ‘wrong’ – it would depend on the specific person involved.

Having said that, there now appears to be confusion around fats.

Are they healthy? And if so, which ones and how much?

There are various types of fat. Some are less healthy and some more healthy. But first, we need to understand what they are and the common sorts of foods that they are found in. Here is a handy ‘traffic-light guide’:

Trans fat: avoid

Processed fats, margarine, pastry, cakes, biscuits, commercial salad dressings, sunflower, soybean, rapeseed & corn oil heated to high temperatures

Saturated fat: eat cautiously

Animal fats (such as those found in meat), cheese, milk, butter, cocoa butter, palm oil, coconut oil, ghee

Polyunsaturated fat: eat regularly

Essential fatty acids Omega-3 & Omega 6, oily fish, chia seeds, linseeds, walnuts, hemp oil

Monounsaturated fat: eat regularly

Avocado & avocado oil, nuts, seeds, olive oil

Everyone should avoid trans-fats as far as possible: they are associated (even in small amounts) with an increase in all causes of death, particularly cardiovascular disease (1).

Although we now think that saturated fat is less harmful than it was previously thought to be, it is still not really a ‘health’ food. This is because it can increase blood cholesterol and other lipids if eaten in excess, or in those who are susceptible. Recent studies have, however, shown that its association with heart disease, diabetes and stroke risk may not be as clear-cut as we used to think (1).

It is really important to point out though, that we know now that replacing the calories saved by switching from a high saturated fat diet to a low-fat diet with processed or refined carbohydrates, is less healthy than just sticking with the higher saturated fat diet in the first place. i.e., sugar and refined carbohydrates are probably worse for you than if you just stuck with the higher-fat diet in the first place (2).

But, switching from a high saturated-fat diet to one that is more abundant in polyunsaturated fats (especially the omega-3 fats), monounsaturated fats (such as olive oil, nuts and seeds) and unprocessed carbohydrates (such as those found naturally in vegetables and whole fruits) is healthier altogether (2).

Certain fats are very healthy, indeed are essential for our good health and are known as the Essential Fatty Acids. We have to get them from our food as we cannot make them in our bodies. There are two types;

Omega-6 fats

You really don’t need to worry about getting enough omega-6 fatty acids in your diet. Almost everyone probably consumes too many of them, as they are found abundantly in plant oils, processed foods, baked goods, salad dressings, snack and fried foods. It is theratio of omega-6 to omega-3 that is most important – and you want to aim to get that ratio as close to around 1:2 omega-3:omega-6 as possible (so make sure you avoid taking any extra in supplements) (3). The UK average is currently a ratio of 1:15!

Omega-3 fats

These are essential for good health, and most people eating a Western diet do not get anywhere near enough. They are found in oily fish, fish oil and algal oil supplements (which is thought to be the best way of consuming them, as the plant-based sources need to undergo a complicated transformation process in the body, which many people have limited capacity to do). Plant sources include, however, walnuts, chia seeds and linseeds. Good oily fish sources include fresh or frozen mackerel, wild salmon and sardines.

Is dietary fat healthy article
So what can we say in conclusion?
  • Not all fat is good and not all fat is bad…
  • … but do avoid trans fats.
  • Enjoy saturated fats cautiously – but it’s worth paying attention to the quality of what you are consuming. The way an animal is raised will change the health profile of its fats (so go for free-range, organic as much as possible).
  • Try not to replace calories from fats with calories from sugar and refined carbohydrates. Don’t forget that vegetables and whole fruits are fantastic sources of unrefined carbohydrates without a grain in sight.
  • Enjoy healthy sources polyunsaturated fats and monounsaturated fats regularly – such as nuts, seeds, avocados, oily fish and olive oil. They are full of fat-soluble vitamins and in the case of omega-3 fatty acids, are essential for good health.
  • Consider working alongside a nutrition professional if you have any concerns about your blood cholesterol, lipids, blood pressure, cardiovascular disease risk or other health worries, as they will be able to tailor individualized advice to your specific circumstances.

(1) de Souza, R.J., Mente, A., Maroleanu, A., Cozma, A.I., Ha, V. and Kishibe, T. (2015) ‘Intake of saturated and trans unsaturated fatty acids and risk of all cause mortality, cardiovascular disease, and type 2 diabetes: Systematic review and meta-analysis of observational studies’, BMJ, , p. h3978.

(2) Hu, F.B. (2010) ‘Are refined carbohydrates worse than saturated fat?112’,American Journal of Clinical Nutrition, 91(6).

(3) Simopoulos, A.P. (2016) ‘An increase in the Omega-6/Omega-3 fatty acid ratio increases the risk for obesity’, Nutrients, 8(3).


Please note that the information on this website is provided for general information only, it should not be treated as a substitute for the medical advice of your own doctor or any other health care professional providing personalised nutrition or lifestyle advice. If you have any concerns about your general health, you should contact your local health care provider.

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