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Fat is a rich source of energy with 1 gram providing 9 kcals. Fat is made up of building blocks called fatty acids and to simplify things these are classified as saturated, monounsaturated or polyunsaturated depending on their chemical structure.

Some of these are essential components of the diet but others can be detrimental to our health if too much is consumed. 

So, whilst the term eat fat to lose fat has some merits, if you are overeating consumption of dietary fat is important for the following reasons:

  • Regular hormonal function 
  • Provides an energy source 
  • Helps to form cell membranes 
  • Forms our brains and nervous systems
  • Helps to transport the fat soluble A, D, E & K vitamins 
  • Alleviate depression
  • Improve body composition 
High fat vs low fat?

At one end of the spectrum, you have extremely low-fat diets like the Pritikin diet where approx 5% of total calories have been recorded - sometimes as low as 10g of dietary fat is recommended per day. Conversely, at the other end of the spectrum, you have ketogenic diets where the recommendations are for consumption of 70% of calories to be consumed from fat per day - which could be as high as 180g-200g per day. 

We definitely do not recommend the Pritikin diet as the fat intake is dangerously low. The ketogenic type diet has its merits and substantial evidence to support its efficacy. However, it is not easy to adhere to. 

Therefore, a more balanced approach would have recommendations for somewhere between 20-30% of total calorie intake from fat. This seems like the most sensible approach from a health perspective and probably the easiest to maintain. 

Good fats vs bad fats?

The terms ‘good’ and ‘bad’ fats are often talked about in the media and in fitness or health magazines but what does that actually mean. Generally, we are talking about fats found in whole foods as opposed to fats found in processed foods. The table below is a good illustration of the difference (Precision Nutrition).

When it comes to fat intake one thing that can be agreed upon is trans-fatty acids in particular really have no place in human nutrition and this is a place where there is little disagreement in the research. Trans-fatty acids have absolutely no nutritional benefits and their impact on human health would appear to be completely negative.

Where can I get my fats from?

The quantity and type of fat that you consume on a daily basis are certainly key factors in optimising your health. 

Monounsaturated fats include avocados, nuts, nut butter, olives, olive oil.

Polyunsaturated fats include omega-3 fats from fish, fish oil and flaxseed. They also include omega-6 fats from most seed oils including safflower, sunflower etc.

Saturated fats include meat, dairy, eggs, butter, coconut oil.

The take home is to keep it simple by including a balance of different fats within your diet, ideally from a diverse diet of whole, unprocessed foods. 

References used:

http://www.precisionnutrition.com/research-review-balancing-fats

http://www.bodyrecomposition.com/nutrition/a-primer-on-dietary-fats-part-2.html/

De Souza R et al. Intake of saturated and trans unsaturated fatty acids and risk of BMJ 2015; 351

Chowdhury R, Warnakula S, Kunutsor S, et al. Association of Dietary, Circulating, and Supplement Fatty Acids With Coronary Risk. A Systematic Review and Meta-analysis. Ann Intern Med2014;160:398-406.