HOW DO I FUEL FOR ENDURANCE?

How many times have you heard the phrase “nutrition is the fourth discipline of triathlon”? Strictly speaking, it should be nutrition and hydration, but the point is that when you’re competing in endurance events that last up to 17 hours, you need an eating and drinking strategy that will fuel you all the way to the finish line.
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What and how much should you eat?
Carbohydrates are the most important fuel for endurance athletes, and it’s good practice to know how many carbohydrates are in a given portion of your preferred nutrition. Your taste buds will help determine what you choose to eat, but there is a bounty of products—bars, gels and chews—that have been designed with athletic performance in mind. Best practice is to select products, which contain multiple sources of carbohydrates (glucose and fructose) as this mix of carbohydrates promotes enhanced absorption.
How much you should eat is a matter of striking a balance between giving your body sufficient fuel and tolerating the intake. If you consume too few calories, you risk bonking or underperforming; too many calories and you could experience GI issues as your gut is unable to process the nutrition, especially at race effort. 
As a general rule of thumb, endurance athletes should aim to eat 60-90 grams of carbohydrate per hour during Ironman events, with athletes typically able to consume more calories and fluids during the bike leg and fewer calories during the run portion of the event.