Once a perceived enemy of athletes, fat is making a comeback. Here's how you can maximize your use of this important macronutrient.
by Kim Mueller, MS, RD, CSSD
Long chastised for its perceived role in a number of health problems, and limited by athletes in favor of the highly-touted carbohydrates, fat is making a comeback with more and more health and sport scientists recognizing its capacity to ward off disease and enhance endurance performance. Read on for a primer on fat, including the latest science and applications as it relates to triathlon performance.
As the most energy-dense nutrient (providing more than twice as many calories than either carbohydrates or protein), fat not only supplies us with much-needed fuel, it also provides essential fatty acids necessary for the transportation of fat-soluble vitamins and the synthesis of hormone-like substances important for certain biochemical processes and growth.
There are four types of dietary fats: saturated, trans, monounsaturated, and polyunsaturated. Saturated fats are found primarily in animal products, including butter, cheese, whole milk, beef, and chicken. Fat can also be found in such plant foods as coconut, palm and palm kernel oil, and cocoa butter. Trans fats, also known as partially hydrogenated oils, are vegetable oils that have been given an added hydrogen ion in processing to essentially saturate the fat, which helps to increase the shelf life of a product. They are found in abundance in stick margarines, frozen foods, pizza dough, pie crust, fried foods, and packaged foods such as chips, cookies, and crackers. Monounsaturated and polyunsaturated fats are found mostly in foods of plant origin, including avocado, nuts, seeds, and olives, as well as some seafood such as salmon and albacore tuna.
A high intake of trans and animal-based saturated fats has been shown to raise LDL (think of it as "least desirable") cholesterol while lowering HDL ("highly desirable") and increasing inflammation within the body. It has also been shown to increase cancer risk. Eating plant-based saturated fats, however, are safe to consume. In fact, some evidence suggests the oil of a coconut may help facilitate abdominal fat loss, thereby lowering risk for diabetes and heart disease. In addition, there is evidence that consumption of certain types of unsaturated fats, such as Omega 3 fatty acids, may stave off inflammation and muscle soreness, thereby aiding recovery. For maximal health benefits, therefore, athletes should focus primarily on fats derived from plants and seafood.
Determining fat needs
The current dietary guidelines, released earlier this year, no longer focus so much on quantifying fat intake (which previously suggested consuming less than 35 percent of total energy intake from fat) and rather encourages making quality fat choices—namely avoiding trans fats and eating more plant-based fats.
The American Heart Association recommends anyone with cardiovascular risk to limit intake of both saturated and trans fat to no more than five to six percent of total energy intake, a good rule of thumb for all to follow. Very low fat diets containing less than 30 grams per day are discouraged as they may trigger hormonal imbalances, loss of bone mass, and compromise athletic performance.
In general, triathletes should aim for a baseline (resting) intake of approximately half a gram of fat per pound of lean body weight. Additional amounts may be warranted throughout a triathlon season to help achieve energy balance on particularly high volume training days and to make sure you're benefitting from your workouts.
Fat and endurance performance
An estimated 7,000-10,000 calories are burned during an IRONMAN competition. Performance on race day, therefore, is highly dependent upon the triathlete’s ability to sustain a high rate of energy expenditure for nine-plus hours with available fuel sources. One fuel source in the body, carbohydrate, has a very small tank, storing only 2,500 calories (as glycogen) between the muscles and liver. This provides enough fuel to carry a triathlete through the swim and early portions of an IRONMAN bike leg before the dizziness ("bonking") and extreme muscle fatigue ("hitting the wall") kick in. Fat, however, has a giant tank storing some 50,000 calories, enough to fuel multiple IRONMAN races. Training the body to become a fat burning machine is a huge part of driving success at the IRONMAN distance.
|Alternate Ways to Train Low, Race High|
|1. Complete longer training session without taking in any carbohydrate|
|2. Complete hard workout after an overnight fast (AKA, no pre-workout breakfast|
|3. Complete two workouts in a day without replenishing carbohydrate between efforts. The hours spent swimming, biking and running in preparation for IRONMAN race day all play into enhancing fat utilization but some research suggests manipulation of (increasing) fat and (decreasing) carbohydrate intake during various phases of training and leading up to race day, a concept otherwise known as "training low, racing high", may drive the body to further rely on it’s abundant fat supply rather than carbohydrate, thereby aiding IRONMAN performance.|
To test these proposed benefits, for 10 days prior to a key aerobic pace training session, block of training sessions, or race day, bump the composition of fat in your diet to approximately 65 percent of total daily energy needs, focusing on plant-based fats. This will be near double the composition typically consumed, meaning that carbohydrate intake/composition will have to drop dramatically or overall calories will be too high and weight gain inevitable. Then, for three days prior to the key training session or race, implement a carbohydrate-loading regimen, targeting approximately four grams of carbohydrate per pound of lean body mass per day. According to one study of endurance cyclists completing two hours of moderate-intensity spinning and a 20k time trial, following this regimen may get you to that IRONMAN finish-line 4.5 percent faster compared to a typical carbo-load protocol.
As a cautionary note, research does NOT currently support the chronic use of high fat diets for performance purposes. This especially holds true for athletes with training protocols that regularly implement higher intensity sessions (over 80 percent maximal aerobic capacity) such as track workouts and time trials where carbohydrate usage is enhanced and glycogen depletion a greater risk to performance. Chronic use of high fat diets can also reduce an athlete’s ability to absorb carbohydrate, which in turn elevates risk for gastro-intestinal issues as well as the performance-inhibiting "wall" when racing "high."
Fat as a recovery nutrient
The stress of IRONMAN training and competition triggers the release of harmful compounds known as free radicals that can penetrate the protective membrane of cells and lead to damage and inflammation. While the body has defense mechanisms to deal with acute inflammation, severe injury or extreme exercise stress can lead to chronic inflammation and the activation of nerves responsible for the sensation of pain—thereby compromising recovery.
Athletes who don’t shy away from fat, especially unsaturated fats, benefit from essential fatty acids (EFAs) called omega 3 (alpha linolenic) and omega 6 (alpha linoleic). Omega 3's are found in the oils of flaxseed, walnut, and fish whereas omega-6's are found in the oils of corn, soy, canola, safflower and sunflower.
The days when fat was considered a forbidden nutrient have been numbered. The latest thinking is that a diet rich in plant-based fats may reduce inflammation, lower disease risk, and aid recovery from sport. In addition, consuming a higher fat diet for 10 days prior to implementing a carbo-loading protocol before IRONMAN race day or some key training sessions may help initiate a favorable response in which the athlete is able to increase fat usage, thereby sparing muscle glycogen and enhancing endurance.
If you want to learn more about the science behind nutrition check out the Sports Nutrition for Endurance Athletes course from IRONMAN U!
Kimberly Mueller, MS, RD, CSSD is a Registered Dietitian and Board Certified Specialist in Sports Dietetics. She enjoys helping others fine tune their nutrition as means to achieve a variety of health and fitness goals with her company, Fuel Factor.