Looking at the latest research on dietary fat for health and body composition
It’s difficult to know which macronutrient is most maligned and misunderstood – carbohydrates, or fats. We all know that the human body needs some dietary fat. But how much do we need? And how much is too much? What are the best sources of fat, and how should you choose a dietary strategy to suit your training goals?
Let’s look at some of the latest research papers in to dietary fats, athletic performance, health, and body composition.
It might help to stop thinking about your fat intake as a singular goal, and to remember that our dietary fat includes all the fat we get from all sources. This can include animal sources (including meat, dairy, fish), plant sources (including plant oils, seeds, nuts, avocados). So although it is useful to compare different types of fat, and to remind ourselves to eat less trans fats and more polyunsaturated fats, we do not eat fats in a vacuum.
When we talk about fat intake, we need to think about it as part of our entire health experience – which is never static.
Let’s clear one thing up before we get into the studies. Dietary fat – the fat we eat – does not lead to body fat (subcutaneous or visceral fat). Excess calories are what leads to increased body fat. But those calories could come from anywhere: fat, protein, or carbohydrates. Of course, fats have a higher caloric load (9 calories per gram, compared to 4 calories per gram for carbs and protein). But dietary fat in and of itself does not directly translate to being fat.
Research seems to agree that we should get 20%-35% of total daily calories from dietary fats. To calculate this, take 20%-35% of your daily calorie goal (for losing, maintaining, or gaining weight). Divide that number by 9. This gives you the grams of fat you should aim for.
Some of the benefits of eating sufficient fat include
1 High satiety (keeping you feeling full and less hungry)
2 Protecting and supporting your immune system
3 Supporting hormone health including the sex hormones
4 Boosting nutrient absorption, particularly fat-soluble vitamins
5 Encouraging better brain health and cognitive function
Monounsaturated fats are found in plant foods and their oils (olives and olive oil, nuts, avocados) such as olives, nuts, and avocados.
Polyunsaturated fats include omega-3 and omega 6. Omega-6 fatty acids are in nuts, seeds, and vegetable oils. Omega-3s are in oily fish, grass-fed meats, chia seeds, and walnuts.
If you’re confused about where to get your fats from, try olive oil, avocados and avocado oil, oily fish, some red meat, nuts and seeds, butter, and coconut oil. But remember to keep track of fat intake and eat in line with your calorie goals. Fat ins’t unhealthy but eating too much (of anything) can be!
If you want to geek out about fats, take a look at these research reviews and published pieces of scientific literature.
A 2009 “Comparison of Weight-Loss Diets with Different Compositions of Fat, Protein, and Carbohydrates”, which set out to examine whether macronutrient breakdown, or caloric restriction, has the biggest impact on weight loss. https://www.nejm.org/doi/full/10.1056/NEJMoa0804748
The published results of this 2010 randomised trial https://www.ncbi.nlm.nih.gov/pubmed/20679559 which outlined “weight and metabolic outcomes after 2 years on a low-carbohydrate versus low-fat diet”.
A 2014 paper following a randomised trial into the “effects of low-carbohydrate and low-fat diets”, which looked at the effects of a low-carbohydrate diet compared with a low-fat diet on body weight and cardiovascular risk factors. https://www.ncbi.nlm.nih.gov/pubmed/25178568
A 2015 study which looked into the “Relative Merits of Low-Carbohydrate Versus Low-Fat Diet in Managing Obesity” https://www.ncbi.nlm.nih.gov/pubmed/26192936
And this 2015 paper https://www.ncbi.nlm.nih.gov/pubmed/26278052 which showed that “Calorie for Calorie, Dietary Fat Restriction Results in More Body Fat Loss than Carbohydrate Restriction in People with Obesity”.
This 2015 study https://www.ncbi.nlm.nih.gov/pubmed/25527677 “A lower-carbohydrate, higher-fat diet reduces abdominal and intermuscular fat and increases insulin sensitivity in adults at risk of type 2 diabetes.”