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The Fat Athlete: Incorporating Fat into Endurance Fueling

April 12, 2016

"The Fat Athlete: Incorporating Fat into Endurance Fueling" was written by Pip Taylor. Pip is an accredited sports nutritionist and accredited dietitian, professional triathlete, author and mother of two. Pip recently had her first book published, 'The Athlete’s Fix’. It goes without saying that fat is important, in fact, essential for our health and wellbeing. Long gone (at least I hope) are the days where fat in any form was vilified as the dietary enemy. Our bodies need fat to function and dietary fat provides the essential fatty acids (EFA) that cannot be synthesized in the body. Fat within the body helps cushion and protect vital organs; provides insulation; is essential to absorb and transport fat soluble vitamins (Vitamins D, E, A and K); to manufacture important hormones including the sex hormones; make cell membranes and the functioning of the nervous system; and the brain is composed largely of fats. And we also use it as fuel. Indeed, fat is an important fuel source for both endurance athletic performance as well as day to day living. Fat as fuel: Carbohydrates have become synonymous with athletes, and the stereotype of endurance athletes includes high carb diets packed with pasta, rice, bread and cereals. And indeed carbohydrates are important and are preferentially burned (as glycogen) for fuel, providing 4 calories per gram of energy. But the body has a limited ability to store glycogen throughout the muscles and liver and for an athlete these energy stores can be blown through pretty quickly resulting in fatigue and performance decline after only 1-2 hours of exercise. Of course additional carbohydrates can be consumed to try to negate this fatigue, but intake and absorption rates are limited. Fat stores in the body, however are almost limitless when compared to carbohydrate stores, and so it makes sense for endurance athletes to want to try and tap into utilizing fat stores as efficiently as possible. Energy stored as glycogen totals somewhere around 2000 calories. But fat, providing 9 calories per gram, can provide around 50 times this amount of energy, meaning that exercise can be sustained for a much longer period of time. Lipolysis (break down and mobilization of fat stores) increases when you start exercising. During any activity, fatty acids sourced from intramuscular fat as well as adipose tissue, are oxidized in the mitochondria of skeletal muscle. Carbohydrates and fat are always oxidized as a mixture, but the proportion of fat and/or carbohydrate that your burn depends on many factors: the intensity and duration of exercise; your diet; your fitness level; how many carbohydrates you consumed before and during exercise; and how efficient you are at tapping into fat sources. Fat adaptation has become somewhat of a buzzword over recent years and with it differing ideas on what it means, and on the best approach to taking advantage of more efficient fat burning. The first thing to note is that increased fat burning does not refer to fat loss or weight loss. It simply means that when fuel is burnt for energy, the proportion swings more towards fat than it does carbohydrates (glycogen). While some individuals are naturally ‘better’ fat burners, there are ways in which you can up regulate fat substrate usage to your advantage. Manipulating diet can teach our bodies to use more body fat as fuel, and many athletes are finding success with higher fat and lower carb diets. Backing this up with research though is more difficult. Although sufficient studies have been able to show that athletes following a high fat diet are indeed able to become more efficient at using fat as fuel, this does not necessarily translate into improved performance. And in fact, being fat adapted also down-regulates an athletes ability to use glycogen stores, which are still essential for faster paced efforts or events which require short bursts of energy (even in endurance events). On the flip side though, athletes who are fat adapted find they do not need to ingest as much fuel during an event, greatly decreasing risk of GI distress, which can of course be a huge performance benefit. Other athletes find that a high fat (and low carb diet) is a very effective way to manage weight, and weight loss in itself can be a performance booster (if warranted). High fat, low carb diets are such a hot (and controversial) topic right now that there are currently more studies underway – it will be fascinating to monitor the results. There are definitely benefits though to becoming more efficient at fat burning and increase metabolic flexibility – or the ability to utilize both fuel sources efficiently. Simply training in a fasted state (assuming no medical contraindications) may be a more manageable way for many athletes to boost fat burning efficiency without some of the potential downsides to a low carb diet coupled with high training load. Training in the morning before breakfast (and especially after a previous evenings workout that has been high intensity and energy depleting, followed by a low carb dinner) will teach your body to become more efficient at utilizing fat stores as in a fasted state the body oxidises more fatty acids. Training with sufficient fuel stores for more high intensity workouts though allows for maximum adaptations and recovery. Fat then is an important fuel source for endurance athletes, but fat has important roles to play in the body beyond that of fuel. Fat for performance and recovery: Anytime you workout, your muscles are put under stress. An appropriate amount of stress triggers adaptations that are essential for increases in strength and endurance. But this stress also leads to inflammation in the muscles. When muscles are overly inflamed, they can be sore, losing power and range of motion. Dietary Omega-3 fatty acids help regulate and reduce levels of inflammation. Omega 3 fats are generally low in many diets while the Omega 6 fats (while essential) are usually plentiful. An imbalance in these fats can promote inflammation, reducing ability of athletes to recover and adapt to training stress. Focus on including Omega 3 fats in your diet such as fatty fish (including salmon, sardines), egg yolks, hemp seeds. Steroid hormones, that control how your body responds to high energy demands and maintain mineral balance are derived from fat. So too are sex hormones, that drive muscle growth and adaptation (as well as other very important functions). A lack of fat in your diet will prevent these hormones from being manufactured in sufficient quantity or from being in balance, impairing athletic performance and recovery. Fats to include: Include natural fats in your diet and avoid trans fats, processed and refined oils (such as corn, soy, vegetable oil) Include:
  • olive oil
  • coconut oil
  • fatty fish
  • fats found naturally in grass fed meats and organic dairy foods
  • avocado
  • nuts and seeds
  • egg yolks
How much? Some athletes thrive of higher fat diets, while others require a more moderate approach. Certainly the days of using exercise as an excuse (or reason) to guzzle down large quantities of carbs (and especially refined carbs) is gone. (There is plenty of evidence to suggest that diets high in refined carbs are damaging to health and will not maximize athletic outputs either.) But there is no one size fits all approach. You can experiment with your own diet to find what works the best, but as always the best recommendation is to focus on diet quality. Do include a plentiful range of healthy fats in your diet for maximum health and athletic benefit, and play around with doing training sessions in a fasted state for boosting fat burning efficiency.