I'll second what Steve said. I dont' use them for short runs, as they take awhile to get into your system, and anything under 6-7 miles really isn't worth it, IMO. You MUST MUST MUST take water with them, or they will have the opposite effect on your body that you intended. My wife can't use them, as they rip her up inside. Just figure out when you start to tire out a little, and take it awhile before that. I go every 40 minutes like clockwork, whether I feel like I'll need it or not....as well as about 15-20 minutes before a run begins. If you're looking for just plain old carbs during a race, sometimes something as simple as fig newtons can be just as beneficial to you...it's a quick jolt of sugar and carbs that your body can easily digest. I've used these well in the past, and my wife swears by them, as well as honey stinger waffles, which are all natural.