Gone are the days of the simple statement that “fat is bad”. While there is still controversy over the impact of certain types of fat on health, and certainly much debate over whether a high fat diet may be more beneficial for endurance sport performance than a high carbohydrate diet, every athlete should be looking to include a range of fats in their diet, largely from natural sources rather than processed foods. Eating fat won’t make you fat either. Yes, it has more calories per gram than protein or carbohydrate, but fat will only contribute to weight gain if your overall calorie intake exceeds your energy expenditure. If you are looking to lose body fat, try trimming your intake of starchy and sugary foods rather than cutting healthy fats from your diet. Fat is more satiating than carbohydrate and therefore satisfies your appetite more, helping to lower your overall calorie intake.
To maintain good health while training for endurance sports, you need to consume a range of different types of fatty acids which are to be found in saturated fats, mono-unsaturated fats and polyunsaturated fats. Fatty acids are essential components of every cell in your body, forming part of the cell membrane. Your brain and nervous system cannot function properly without a healthy cell membrane. Fat is also needed to absorb and transport the fat soluble vitamins A, D, E and K. The essential fatty acids linoleic (known as omega 6) and alpha-linolenic (known as omega 3) can only be obtained from food. These types of polyunsaturated fatty acids are necessary to produce hormone like compounds that reduce unnecessary blood clotting, boost immune function and reduce inflammation – all important to an endurance athlete – although excess linoleic acid, found in many vegetable oils used in cooking and processed food production, produces hormones that conversely lead to inflammation, promote blood clotting and restrict arteries. So a good balance is required between the omega 3 and omega 6 fats that you consume. Most people consume too much omega 6 and not enough omega 3.
To help you achieve a good balance of fats in your diet, here’s my list of the best sources of each type of fat. Choose at least one food from each list every day, ideally two to three, depending on your energy requirements. Bear in mind that foods contain a mix of fatty acids in different proportions, not just the type they are listed under, so may be a good source of more than one type of fat.
- 2 eggs
- 2 tsp butter
- 1 pot of natural or Greek yogurt (c 150g): full fat or low fat, not zero fat
- 250ml of full fat or semi-skimmed milk, not skimmed milk
- 150g of grass-fed/free range meat or poultry
- 1 tbsp coconut oil (for cooking)
- 200g coconut milk
- 1 tbsp extra virgin olive oil (for salad dressings. Do not use for cooking)
- 1 tbsp olive oil (for low temperature cooking).
- Half an avocado
- 6 olives
- 6 macadamia nuts (nut with highest monounsaturated fat content)
- 1 tbsp extra virgin rapeseed oil (for moderate temperature cooking)
Omega 3 polyunsaturated fat
- 100-150g oily fish, eg salmon, mackerel, trout, herring, sardine, fresh tuna (not tinned), crab, mussels
- 6 walnuts (nut with highest omega 3 content)
- 1 tsp pumpkinseeds
- 1 tbsp extra virgin rapeseed oil (for moderate temperature cooking)
- 1 tbsp flaxseed oil (for salad dressings, do not use for cooking)
- 1 tbsp ground flaxseed
- 1 tbsp walnut oil or hempseed oil (for salad dressings)
- 2 omega 3 enriched eggs
- 1 tbsp chia seeds
- 100g tofu (soya bean curd)
Omega 6 polyunsaturated fat
- 1 tbsp hempseed oil (for salad dressings)
- 30g of mixed nuts (eg almonds, Brazils, cashews, pecans, pistachios, peanuts)
- 1 tbsp nut butter (eg almond, cashew, peanut – avoid those with added sugars and palm oil)
- 1 tbsp sesame oil (for salad dressings, do not use for cooking)
- 1 tbsp sesame seeds or sunflower seeds
- 100g of hummus (contains tahini which is sesame paste)
The type of fat which you should definitely avoid is trans fats. Most of these are formed artificially during the commercial process of hydrogenation when vegetables oils are converted into hardened fats. Trans fats have been shown to increase levels of small dense LDL cholesterol while lowering levels of beneficial HDL cholesterol, both of which are associated with an increased risk of heart disease. Trans fats are not as common in processed foods as they once were, but do check labels for hydrogenated or partially hydrogenated fats, which may be found in some fast food, takeaways, pastries, cakes, biscuits, cereal bars and margarines.
This brings me onto the subject of saturated fat and heart disease risk. For the last 30 years, government guidelines have urged us to cut saturated fat consumption as it was thought to raise LDL cholesterol levels, which in turn contribute to an increased risk of heart disease. This was based on Ancel Keys’ Seven Countries study, the results of which have been increasingly questioned after more recent studies have shown the link between saturated fat consumption and heart disease to be weak. 1 2 Some saturated fats actually raise levels of HDL, which transports cholesterol from the arteries to the liver where it is excreted or reused; good levels of HDL are associated with a reduced risk of heart disease. In some people, consuming large amounts of saturated fat may lead to an increase in LDL cholesterol levels – this is likely to be genetically determined – but this is the large type of LDL that is not associated with the development of atherosclerosis (narrowing of the arteries). For an increased risk of heart disease, LDL needs to be in the small dense or ‘oxidised’ form; this is caused by a process of inflammation. Eating plenty of anti-inflammatory foods including vegetables, monounsaturated fats and omega 3 fats will help to prevent this from occurring.
Finally, I’d like to touch on the current controversy over low carb, high fat diets (LCHF) and endurance sports performance. Will cutting carbs significantly while consuming 60-80% of your diet from fat make you a faster runner, cyclist or triathlete? Anecdotal evidence suggests that some athletes, particularly those competing over longer distances at lower intensities, eg ultra-running, are seeing success from this approach. But as yet there are no high quality research studies to back this up, although one is on the way from Dr Jeff Volek (the FASTER study). At this stage, the bulk of research points towards carbohydrate being the main fuel source for most endurance events, at least those where intensity exceeds about 65% of VO2 max. However, it is thought to be possible to increase your rate of metabolic efficiency, ie the point of intensity at which you still able to rely on fat as fuel, by changing the balance between carbohydrate and fat in your diet. This is best done as part of a periodized nutrition plan, with a higher fat diet during base training and more carbohydrate being consumed as race season approaches. See my blog post on Metabolic Efficiency for more details. There is a concern that if you become too good at oxidising fat as fuel, your ability to switch to the carbohydrate oxidation required for higher intensity racing may be compromised, so training at last some of the time on a higher carbohydrate intake may be advisable. For a balanced view on the high fat versus high carb debate, I suggest reading this recent blog by well-respected sports scientist Asker Jeukendrup.
In summary, I recommend that you:
– Avoid following a low fat diet
– Consume a range of fats from natural sources every day to support your health
– Change the balance between fat and carbohydrate in your diet according to the phase of training that you are in.
Jo Scott-Dalgleish BSc (Hons) is a BANT Registered Nutritionist, writing and giving talks about nutrition for endurance sport. Based in London, she also works as a Registered Nutritional Therapist, conducting one–to–one consultations with triathletes, distance runners and cyclists to help them eat well, be healthy and perform better through the creation of an individual nutritional plan. To learn more about these consultations, please visit www.nutritionforendurancesports.co.uk
1 Astrup et al. The role of reducing intakes of saturated fat in the prevention of cardiovascular disease: where does the evidence stand in 2010? American Journal of Clinical Nutrition 2011. 93 (4): 684-688.
2 De Oliveira Otto et al. Dietary intake of saturated fat by food source and incident of cardiovascular disease: the multi-ethnic study of atherosclerosis. American Journal of Clinical Nutrition 2012. 96(2): 397-404.