How can you maintain good energy when you’re exercising for longer than 60 to 90 minutes? By eating enough calories of foods that settle well…!
The standard recommendation for fueling during endurance exercise has been to target 1 gram of carbohydrate per minute of exercise (60 grams of carb per hour, the equivalent of 240 calories for a 150 pound athlete). The research, originally done with just glucose, indicated consuming more than 60 grams of glucose per hour offered no additional benefits. The body has a limited number of glucose transporters and can carry only 60 grams out of the intestines, into the blood stream and to the muscles.
Recent research indicates consuming a variety of sugars (that is, more than just glucose) allows more fuel to become available per hour. That's because different types of sugars (carbs) use different transporters. Generally, athletes consume more than just glucose. (Sports drinks, for example, tend to be glucose+fructose.) Let's say you eat a banana that consists of many different types of sugars and uses many different transporters. Your muscles will have access to more fuel (up to 90 g carb/hour; 360 calories) than if you consume just one kind of sugar (as might happen with some engineered foods).
Variety is a wise idea—as is practicing yoru fueling during long training sessions so you can learn what works best for your body. Some people like engineered sports candy and gels, others prefer dried pineapple and gummy candy. Take your choice--just experiment during training to determine if 200 to 300 calories per hour is the right amount for your body.