Diet will affect which fuel is used.

Fat metabolism is very sensitive to the interval between eating carbohydrate and the onset of exercise. A high carbohydrate meal will cause the pancreas to excrete insulin, which inhibits the breakdown of fat. Hence, the body will be forced to rely on carbohydrates for fuel. The body will always go for the kindling before the log. Therefore, if you’re trying to burn fat, then carbohydrates should not be consumed within a couple of hours of the activity. If the exercise or cardio session is going to be a long one (1 hour +), than carbohydrates will have to be consumed at some point during the activity. It’s the ability of the muscles to oxidize FFA’s, rather than the increase in the mobilization of FFA’s from adipose tissue. Like anything else, the more you do something, the better you get at it. You must first learn to become a great “fat burner” through adaptation of exercise. Keep the exercise intensity low, so you can learn these energy pathways.
Periodization is key here. Give the body time to adapt before you increase the intensity to take advantage of the effects of EPOC. If you’re exercising on an empty stomach in the morning and want to lose fat, go easy and for not longer that 30 - 45 minutes. Then, eat a carbohydrate that is easily digested before you lift weights. Again, it depends on the individual and their ability to store carbohydrates whether or not they’ll need to eat before a strength work-out following a cardio session of that length and intensity.

After you workout
Following an exercise session it is important to elevate glucose as soon as possible to provide a substrate for glycogen synthesis. Glycogen synthesis can occur more rapidly if carbohydrates are consumed within a half hour to an hour after exercise. It helps to have a bagel or sports drink available after a hard work out. Full muscle glycogen replenishment for a competitive endurance athlete requires a diet consisting of greater than 60% of total calories over a two day period. (8)
Also, consider the person and the goal. Endurance athletes such as marathon runners and road cyclists or collegiate wrestlers have a problem keeping body fat. They won’t be as interested in body composition as opposed to pure weight compared to a body builder. What is the experience of the exerciser, what gender, what age, etc.. Keep in mind these concepts though. An endurance trained athlete relies less on carbohydrate and more on fat as fuel. Fit people are simply more efficient at using fat for energy. A novice exercisers body is inefficient, relying primarily on carbohydrates as a fuel source until the body “learns” to use fat. I hope this helps you reach your
fitness goal.

__________________

Disclaimer: Hypermuscles.com does not promote the use of anabolic steroids without a doctor's prescription. The information we share is for entertainment and research purposes only.