There is definitely a debate over fuel versus no fuel; however everyone I know that trains regularly for races uses fuel in some form or another. I have always used fuel in my training and on race days, so I highly recommend some type of fuel while you are doing long runs and of course on race day.
When you find the fuel that works for you – stick with it! (Just as you should with your pre-race/pre-long run meal.) As I understand it fuel increases performance by supplementing your body while you are running. When you are running for longer than 90 minutes you use up all the reserved energy that your body stores naturally. Fuel helps replace all that energy that your body has burned up and used during your longer workouts. When all your reserves are depleted fueling during the run or race according to a schedule will give you the boost you need to stay on pace and finish strong without ever letting your body get depleted of necessary energy. It also helps with your recovery after long runs and races as you are not finishing the run/race sputtering on fumes like an car with an empty tank of gas. Just like a car engine if you keep your body fueled through the whole workout you will achieve your highest performance potential.
When you are running for longer than 90 minutes you are going to need to fuel. Typically you fuel before 90 minutes of running and then every 40-45 after that, but fueling schedules can be different for each runner. Some people may burn energy faster than others so just find what feels right for you. Of course if you feel hungry or low on energy you can always consume fuel outside of your scheduled fuel break.
Personally, I fuel at the first hour mark and then every 35-40 minutes after for the rest of the run or race. You may also want to time your fuel with water stations on the course as some forms of fuel are hard to swallow without water. (This of course won’t matter if you carry your own water. I don’t like to carry water for races so I rely on water stations if I need water during the race.)
Don’t wait until your last couple long runs to figure out what fuel type and schedule works for you. Test out your like/dislike for certain brands and types even on shorter runs that don’t take you past the 90 minute mark just so you can get your body use to the intake of something while running.
There are a lot of different options out there, but most come in a gel, gummy or jelly bean form. Also, there are options with or without caffeine. You will need to test out what you like for taste and effectiveness. Some people experience an upset stomach when fueling because of the up & down motion of running and the quick hit of energy they add to their body through fueling. Don’t get discouraged from fuel if this happens to you; just try a different brand or a different type.
I have experience with the following types:
Gel Form: GU is the most popular brand and the kind I have used in the past. I recommend the chocolate flavor as it tasted like pudding to me J Gels can be harder to “choke” down without some water, but it can be done. Very easy to carry and eat while on the move. (Other popular brands are Power Bar Gel and Clif Shot Gel)
Gummy Form: I love Clif Shot Bloks! All the flavors are yummy and they have a good variety without caffeine since I don’t drink caffeine anymore L My choice of fuel is the gummy form because I felt like I was eating candy and it was easy to consume without water if need be. Also very easy to carry and eat while on the move. (Other popular brands are GU Chomps and Luna Sport Moons)
Jelly Bean Form: I have tried Jelly Bean Sport Beans, but I was not a fan. Even though I have a huge sweet tooth they were too sugary for me and one serving seemed like a lot of beans! I also thought that they were harder to store and eat while running as I dropped a few on the ground at times. However, I do know people that like these a lot.
I do not have experience with gummy bears, twizzlers, fig newtons, etc but I know people use them instead of packaged sport fuel. If you want to try something like this I think the goal is to hit around 100 calories per fuel serving with 0-2g fat, 20-25g carbs and 5-6g sugar.
Bottom line is just test it out until you find something you like – then stick to it!