I began using Ultra Fuel for ultrarunning. I started with the form that came in 16 oz. glass bottles and had 400 calories. Twin Labs then changed the product so it came in 18 oz. plastic bottles and still had 400 calories. Finally they got rid of the liquid form; now they only sell the powder, which is supposed to be made with four scoops of powder, which contain a total of four hundred calories.
What I like about the powder is that the flavoring and color is designed to be mixed at 400 cals per 16 oz. If you use one quarter of the recommended powder per bottle then you get a liquid that has a much milder taste than a typical sports drink. During very long events the tast of super strong flavored drinks can become annoying, so the mild taste is a big win. Another reason for mixing it to a lower concentration is that at full strength it will slosh around in your stomach for a while. With one scoop instead of four, you get a 100 cals/bottle, and that is more easily absorbed. Also using one scoop per bottle yields 66 servings per large container, which are failry cheap if ordered online, and the cost per bottle is lower than most alternatives.
The downside is that if the amount of powder is cut to one fourth then not only are the calories being cut in four but the electrolytes are also. I supplement the mix by the contents of a half or a whole electrolyte capsule like Saltstick. Instead of Saltstick you could put in a pinch salt and/or a pinch of Lite Salt, which contains potassium choloride.
