Sure, if you are going out for a short run (up to about 75 minutes), you should be fine for an easy run or race. It’s when you get into longer distances that you can most benefit from giving your muscles and brain what they need to run. Not only will the run feel easier overall (your rate of perceived exertion will be easier), you’ll set yourself up for better recovery for that next run.
If you are running for less than 1 hour and 15 minutes, you should be fine with just water.
If you are running from 75 minutes up to 3 hours, you should aim for 30 – 60 grams of carbohydrates per hour.
What about a sports drink? Depending on the brand, sports drinks typically contain about 50 calories or 10 grams of carbohydrates per 8 ounces. That may be enough for shorter runs but for longer runs, you will probably need more carbohydrates. And trying to get in more calories necessitates drinking a lot more liquid than you may want to drink. A tummy full of liquid can sometimes get uncomfortably sloshy! In races, you cannot guarantee that sports drinks will be mixed properly.
Gels are the most typical source of fuel used by runners. One packet = about a 100 calories or 20 grams of carbohydrates. So if you have a gel about every 45 minutes, you are getting within the recommended amount of calories. That may seem like a lot and for many people their gut will revolt! This is where training your system to take in calories regularly is important. And it’s really does help to try different gels to see what works best for you. All gels should be taken with a couple swigs of water which helps absorption.
Some people find that a whole gel can just be too much. Either you can split the gel and take a little over the course of a mile or there are other options like sports jelly beans or chews. These small, chewable bits of energy can be more easily distributed over the course of a run so you have sustained fuel.
And yes, you can also eat real food! Gels are easy but there are other options which will do if for whatever reason you want to try them. Remember that you are aiming for easy to digest carbohydrates. Fat and protein and fiber can all take longer to digest and for some cause gastrointestinal distress. Some easy sources of carbohydrates that can be easily carried are pretzels, white bread with jam or honey, rice balls or even candy like gummy bears.
When you are out for a run, make sure to eat earlier and often. Make a plan! if you know you need 30 to 60 grams of carbohydrates per hour, how will you meet that demand? Experiment with different types of fuel to see what works best for you. While you can run up to 75 minutes with no fueling, to properly fuel your run you should having something to eat after 30-45 minutes of running. Why make a run more challenging than it should be? Fuel up!