Including fat in pre-training and pre-race meals is not only something I practice but something I advise my athletes to do on occasion. My reasoning is that training for a triathlon you may be in for a long day consuming little but simple sugars so you need to set up your body to metabolise fat and get in some better nutrition.
This is a little difficult for me as the scientific evidence in favour of “fat adaption” (ie training your body to burn fat over carbohydrate) is shaky to say the least.
While short term high fat diets over several days negatively affect glycogen levels and performance, longer term diets over weeks to moths can overcome this. Protocols employing short term fat adaption however can be beneficial when a period of carbohydrate restoration is employed. For more detail I suggest this review (http://www.ncbi.nlm.nih.gov/pubmed/22301836).
I need to say I have doubts prescribing high fat diets for any number of days or weeks as the potential negative health effects are not really clear and also it is difficult to control overall calorie intake leading to weight gain.
That is why I was interested to read a report which fairly fairly well approximated my own pre-race routine(http://www.ncbi.nlm.nih.gov/pubmed/22852054
). This is extremely limited in scope with a total of only 8 subjects but still of interest.
What they found was that a single high fat meal after a period of carbohydrate loading was enough to boost fat metabolism, reduce carbohydrate metabolism and increase time to exhaustion in a running test. More over this effect was enhanced when the subject consumed an energy jelly on commencing exercise. This is interesting as it suggests once you are primed to burn fat, additional carbohydrate can facilitate it.
Athletes often avoid fat because it is perceived as unhealthy and they are often trying to control weight. However by excluding fat from the diet you can switch off your ability to burn fat and your metabolism will become geared to burning carbohydrate. Normally this is not an issue but when you get to the run stage of an Ironman triathlon it could come back to bite you and you will have to slow down to an intensity where you can burn fat.
I recommend avoiding “low fat” diets and including more fats in some but not all pre-training meals to see how it affects you and not solely relying on carbohydrates.
If you have a long ride or run tomorrow why not try:
1) Eat carbohydrate the day before to glycogen load
2) Include more fat at breakfast eg eggs with butter, cheese, avocado or pastry.
3) Begin ingesting carbohydrate during exercise in line with your energy requirements
If it works for you in training then use it in a race. One question is when could you have this meal before an event and still have an effect? I am wondering if my steak and chips the night before an Ironman has helped me in the past or is just a guilty pleasure.