Because making your own racing and training fuel isn't always feasible.

We’re with you: We’d rather eat a home-cooked meal than suck down an energy gel or other prepackaged sports nutrition any day. But to train hard, you need calories, and when you’re hammering through a workout or rushing from the pool to the office, sometimes the best way to get fuel is from inside a wrapper.

“Bars and gels are a super easy, portable way to get nutrition in if you don’t plan ahead of time,” says Alex Borsuk, a registered dietitian and ultrarunner from Oregon who works with endurance athletes around the world. “It’s just a matter of balancing those [products] in the right ratios and the right amount of calories.”

The key to buying prepackaged sports nutrition products is knowing how you plan to use them. After about 90 minutes of hard exercise, your body begins to exhaust its supplies of glycogen, a form of carbohydrate stored in the liver and skeletal muscles. To keep from bonking, Borsuk says athletes should take in about 300 calories per hour after that point. Look for a product rich in simple sugars, which digest rapidly for a quick energy boost, as well as sodium to replace electrolytes lost through perspiration.

In addition, Borsuk recommends looking for products that include a small amount of fat, which studies show can provide longer-lasting energy and reduce GI distress over long efforts. Don’t overdo it, though: Fat and protein digest more slowly than carbohydrates, and in large amounts can cause race-day gut issues.

Another option, especially for athletes training in hot climates, is to drink your calories. Hydration mixes provide quick-burning carbs that you can sip right from your bike bottle. At about 200 calories per 16 to 20 ounces of liquid, some athletes might find this a little too sloshy to be their main nutrition source, but for others it’s an easy way to stay fed without having to chew on the run.

After a race or workout, athletes should follow what’s called the 30/90 rule. In the 30 minutes following hard exercise, Borsuk says the human body has a heightened ability to replenish its glycogen stores; take advantage of that window by consuming a carb-heavy bar or a couple of gel packets. Then, within 90 minutes, kickstart your recovery by taking in a full meal that contains a good balance of protein, carbs, and fat.

While every athlete’s body is different, Borsuk prefers to stick to products made with whole-food ingredients to minimize the chances of GI distress; one of her favorites, Spring Energy gel, is made with a base of rice, fruit, honey, and molasses, with nut butter or coconut oil for a touch of healthy fat. Whatever you choose, though, make sure you try it in training before bringing it to the starting line.

“It doesn’t matter how hard you train or what kind of shape you’re in,” says Borsuk. “If you mess up your nutrition, that could be the end of the race for you.”

Know Your Prepackaged Sports Nutrition Options

Bars
They’re easy to find and offer the most “real food” experience, but they’re also bulky and sometimes have too much protein and fat to eat during a really hard workout.
Gels and Gummies
Both are mostly made up of quick- burning simple carbohydrates, which makes them a great choice for mid-race or training fuel. Most feature a mix of different types of sugars; experiment with various brands to find out which sits best in your stomach.
Powder Drink Mixes
Drinking your calories lets you hydrate and fuel up at the same time. Pay attention to label directions when you mix these powders with water: Add too much mix, and you could end up dehydrating yourself as your body siphons off extra water to process it.

A note on caffeine: In moderation, caffeine can give competitors a much-needed boost during race day. But don’t overdo it: for those who can tolerate it, Borsuk recommends taking in one caffeinated gel per hour as a general guideline.