Now it’s time to look at how fats fit into your diet as an endurance athlete. Let me get the scientific gobbledegook out of the way first. (If you missed Part 1, where I talk about the role of fat in sports performance, you can find it here.)
Most of the fat found in your body and foods is a type called triglyceride. This is a compound made up of three fatty acid molecules held together with glycerol. Fatty acids have varying degrees of saturation – saturated, mono- and polyunsaturated. These fatty acids all have important functions in the health of our bodies and minds.
Saturated fats (SFA) are found in land animal derived foods (meats, poultry, dairy) and are usually solid at room temperature – like butter and lard. While eating a lot of saturated fat is associated with higher overall cholesterol and LDL levels and increase heart disease risk, it isn’t the primary cause of high cholesterol. Saturated fatty acids are not all the same, and you need a small amount of them in your diet. Short chain SFA are important for the health of your digestive system – you can get these from butter and cheese however your body can readily make these from the fibre in plant foods. Coconut and palm oil are also saturated fats but with a medium chain structure which has led to claims that they have a better fat profile and health benefits. This is partly because they are more quickly converted into energy than other fats. If you have high cholesterol be aware that coconut and palm oil can raise LDL and total cholesterol levels.
Polyunsaturated fats (PUFA) are found in plants and come in two forms – omega 3 and omega 6. These fats are essential to produce eicosanoids, which are key substances for the normal function of your blood pressure, blood clotting, smooth muscle contraction (eg. your heart and intestines), healthy inflammatory processes, and immunity. Omega 6 has a pro-inflammatory function, which is critical for initial healing from injury or illness. Omega 3 improves HDL cholesterol, reduces blood pressure and can reduce arthritic symptoms, and is often referred to as an anti-inflammatory. However, not enough omega 3 and too much omega 6 fat in the diet is not good for you, as it disrupts the proper function of the inflammatory pathway and can lead to excess inflammation in your body. Getting this balance right is important for your health, and I’ll discuss this below.
Monounsaturated fats (MUFA) are also found in plants and have similar healthy cholesterol promoting properties as PUFA. They are sometimes referred to as omega 9 fats.
There is a fourth type of fat found in our diets called trans fat. While tiny amounts of this exist naturally in meat and dairy, it is harmful for our bodies in its man-made form. This occurs when plant oils are processed via hydrogenation and turned into solid forms of oil, like margarine and other spreads. Trans fats are directly linked to unhealthy cholesterol levels and heart disease. Not all food labelling requires trans fats to be mentioned, so if you see the words ‘hydrogenated’ on a food item, leave it on the shelf!
There are 2 other types of fats found in our food and bodies which are not essential for us to include eat.
Sterols are found in animal-derived foods as cholesterol and in plants as sterols and stanols. Your body can make all the cholesterol it needs for proper function internally, so you don’t need to add dietary sources. Cholesterol is necessary for the formation of steroids (such as the sexual hormones and adrenal hormones), it helps with cell membrane function and is necessary for the absorption of fats via the production of bile.
Phospholipids have the special characteristic of being water soluble, unlike other fatty acids which are insoluble. They are important for the healthy function of cell membranes and transporting molecules in the body. We don’t need to get these from our diet as our bodies can make these for itself.
Dietary Fat Recommendations
Each gram of fat provides 9 calories of energy. This makes it a higher calorie food source than carbohydrates and protein, as they both provide only 4 calories per gram.
I’m not an advocate of calorie or gram counting, and while nutritional science can provide an idea of optimal ranges for nutrient intakes, your individual constitution plays a big part in how well you process and use specific nutrients.
As an athlete, your fat intake should be considered in the context of your training energy needs, protein requirements and carbohydrate intake. (You can find out more about Protein here.) You can be healthy and performing at your peak with anywhere from 20 – 40% fat intake daily.
The type of fat you add in your diet is just as important as the amount, because of the effect the different fats have in your body.
The best advice I can give you is to ensure that the majority of the fat in your diet comes from whole, unprocessed, natural food sources – and in particular nuts and seeds. Nuts and seeds have high amounts of both omega oils.
Plants oils are highly concentrated fat sources, and their quality can vary greatly depending on processing, storage and cooking. Light, heat and oxygen can turn oils rancid, and you can’t tell if an oil has gone bad just by smell or taste. This is also an issue with the plethora of fish oil supplements available, as research has shown many of these contain oils that have gone bad in the manufacturing process. I recommend you buy oils that are locally sourced, and plant foods (nuts, seeds, grains) that are packaged and sealed, rather than scooped from a bulk bin, to minimise the risk of rancidity.
There is some debate about whether saturated fat directly causes heart disease. However, there is enough evidence to suggest that replacing excess saturated fat, highly refined (processed) carbohydrates and sugars in your diet with unsaturated fats (especially omega 3) and high fibre carbohydrates will reduce LDL cholesterol and total triglycerides, improve your cholesterol profile and reduce your risk of heart disease.
As a general rule, you should prefer plant-derived fats over animal-derived fats, as this will reduce your overall saturated fat intake and increase your intake of anti-inflammatory nutrients. Plants do contain trace amounts of SFA, but their predominant fats are PUFA and MUFA.
The omega 3/omega 6 ratio is essential for balancing the inflammatory processes in your body. The recommended omega 3:6 ratio for good health is between 1:2 to 1:4, yet the average western diet is more like 1:12 or higher. Unless you eat a lot of fish, you need to make an effort to include enough omega 3 in your diet. If you have any health complaints with an inflammatory symptom, my first advice is to immediately address your omega 3:6 ratio.
Be aware of hidden fats in processed and packaged foods. These often contain trans fats, saturated fats and omega 6 oils – and it is these hidden fats that can lead to health problems without your knowledge. Their primary offence is initiating the pro-inflammatory process. These hide in plain sight in food items like ready-made meals, fast food takeaways, pizza, biscuits, margarines, potato and vegetable crisps, snack/cereal bars, breakfast cereal/granola, pre-made sauces and dressings, and many more.
Monounsaturated fats are found in most nuts and seeds, peanuts, avocado, olive oil and canola oil.
Omega 3 Polyunsaturated fats are found in fatty fish (eg. salmon, sardines, halibut), fish oils and in these plants – flaxseed, chia, canola, soya, walnut, black currant seed.
Omega 6 Polyunsaturated fats are found only in plants – the most common sources are oils such as sunflower, corn, hemp, soybean, walnut and sesame.
Nutrient timing – when is it best to eat fats?
The general rule in sports nutrition is to keep fats away from exercise sessions, as they take longer than carbohydrates to be digested, and this can sometimes cause digestive problems while exercising. In theory, this means you wouldn’t eat any foods with fat within at least two hours of activity.
From a practical point of view this becomes difficult if you’re an athlete doing high volume training, and multi-discipline training with two or more exercise sessions in a day. In these situations, choosing lower fat options makes sense, until you know whether you can tolerate fat well during exercise.
I did my first Ironman earlier this year on foods containing fats with no problems on the run. I ate muesli bars for the first 90km, then switched to croissants with peanut butter and jam for the second half of the cycle. On the run I only ate potato chips, mostly for the salt taste. On race day morning I had added croissants as a back-up plan in case I didn’t want sandwiches, as I sometimes found bread too heavy in my gut on long rides. By 5 hours into the race it was croissants that I craved, so I listened to my body, and it worked perfectly for me. However, that combination may have you retching in the gutter! Croissants and chips aren’t part of my normal diet, but I’ve learnt through trial and error that my body prefers foods with starch and fat over sports supplements and sugars when doing big mileage sessions. I intend to fine tune this more for my second Ironman race.
My advice is to learn what foods you perform best on, both pre-training and during training. This may take months to sort out, as running puts your digestive system under a lot more stress than cycling or swimming.