Fat is a very interesting nutrient. It's amazing how we have been taught to avoid it at all costs. Even when you turn on the TV, you are bombarded by commercials that equate fat to the plague.
Fat, like all other nutrients, has a very important role in a balanced diet. Unfortunately, a diet that is high in fat can lead to severe health complications which result in death. This is scary, and should not be touched upon lightly. The over consumption of fat in America is an epidemic, except that consuming fat is voluntary and easily moderated with the proper knowledge.
Fat is vital for a number of reasons, such as: our cell walls require fat , our organs use fat as a cushion from impact, fat is used to insulate ourselves from the cold, and much more. In reference to physical activity, fat is used for long term energy. A great comparison for the use of fat is like that between two runners. One runner is a sprinter and the other runs marathons. A sprinter engages in anaerobic activity, which does not require oxygen intake. Conversely, a marathon runner engages in aerobic activity, which requires oxygen intake. Since the utilization of fat requires oxygen, and the utilization of carbohydrates does not require oxygen, the marathon runner uses fat for energy. On the other hand, a sprinter uses a stored form of carbohydrates called glycogen, which does not require oxygen. If you think about it, a sprinter can literally sprint a 20-yard dash and hold his/her breath. Although I would not recommend it, it's true. A marathoner on the other hand can absolutely not run a marathon and hold his/her breath. Since carbohydrate stores only last about 45-50 min during physical activity, fat becomes the main source of energy.
Fat also slows down the metabolic absorption of nutrients. In other words, if you eat a lot of fat, your body will take a longer time to absorb nutrients when compared to not eating a lot of fat. This issue can complicate pre and especially post workout meals. A high fat meal before a typical gym workout is not recommended because your body will not have enough time to metabolize it all. Your body will benefit from a pre-workout meal that is high in complex carbohydrates and moderate in protein around 2 hours before exercise.
High fat meals as a form of post-workout nutrition are not beneficial because your body is starving for quick acting simple sugars to replenish glycogen stores and for protein to rebuild muscle that has just been broken down. Eating a lot of fat after a workout will compromise the absorption of vital carbohydrates and protein.
Fat (and I mean healthy unsaturated fat) is best to eat in the middle of the day or at least a meal before or after a pre/post workout meal. Use fat to your advantage! It's very filling and keeps us satiated. Having fat (such as peanut butter) during a mid-meal snack is awesome because you don't have to eat a lot of it and it will keep you full until your next meal. Just be aware that it is difficult to regulate fat intake and it is over twice as hard to burn than carbohydrates or protein!