You've heard it before and by now you know it to be true: your body is a machine.

Given the right food, it allows you to crush tough workouts, long runs, and whatever else it's subjected to.

Eat the wrong stuff, and you’ll simply run out of gas, or end up with a bad case of the bloating and flatulence variety.


Dairy is on category to take a pass on pre-workout, says Sam Accardi, lead dietitian at Mind + Matter, LLC, a nutritional consulting company in Arlington, VA.

Its sugars are slow-digesting and can cause an upset stomach for some people. That mouth-coating sensation that dairy leaves behind may also be unpleasant as your breathing becomes heavy during exertion.

This goes for yogurt, too. However, in two-percent varieties, both are excellent recovery foods, providing a great balance of protein, fat, and carbohydrates.


Probably the most obvious entry on this list, alcohol is a real endurance killer when it comes to workouts and much more.

“Your nervous system is needed for coordination and activation of muscle fibers,” says Joey Gochnour, owner of Nutrition and Fitness Professional.

“Just like caffeine can wake it up, alcohol can slow it down.” These effects can last well into the next day, not to mention the dehydration you can experience.

If you know you’ll be doing a long run, bike ride, or training session, lay off the bottle the night before, and really all throughout your training if you’re prepping for an endurance event like a marathon or a triathlon.


The goal of carb-loading is to increase your muscles’ reserves of glycogen, the fuel that your body can turn into glucose as needed for energy.

“It takes upwards of a week to maximize muscle glycogen stores,” Accardi says. Plus, too many carbohydrates too close to go-time will just weigh you down, the opposite effect you were going for.

For two weeks prior to an endurance activity that will last longer than 90 minutes, he recommends increasing carbs slightly, to about 70 percent of your daily calories, while decreasing fat consumption to keep total calorie count the same, as you’re also tapering down on your training. “I would trial this a few months out from competition to see if it works for you,” he says. “Not everyone’s body responds the same way.”

Low calorie foods and drinks

Artificial sweeteners, particularly sugar alcohols, aren’t really digested by the human body, and so can have a loosening effect on some people’s systems. Foods that use them may include soda, vitamin-enhanced water, and even drinks designed to give you energy and enhance performance.

In fact, many diet-friendly snack and protein bars carry a warning that they may cause intestinal distress. Just what you want before a 25-mile bike ride.

Nuts and dried fruits

It seems like a good choice for the long haul, considering it got its name ostensibly for its use on hikes. The blend of seeds, nuts, and dried fruit is full of vitamins and fiber. The latter, however, is where gorp goes wrong as a pre-endurance activity food.

“Eating foods high in fiber too soon before a hard workout can cause GI distress,” says Kaye Anne Starosciak, a registered dietitian. Further, the fiber in trail mix is generally the insoluble kind, meaning it doesn’t dissolve in water and your body can’t really digest it, so it goes right through you. “Insoluble fibers are likely to cause cramping and/or diarrhea,” Starosciak says.

Anything fried

Foods high in fat take an extremely long time to move through the digestive system. Not only that, “fat molecules are harder for your body to break down and use for energy,” says Charmaine Jones, registered dietitian and owner of Food Jonezi nutritional services.

Eating them right before a workout is obviously dumb, but you should really avoid them alltogether, even a fast food breakfast could impact your performance that night: “Fatty foods can make you feel so sluggish that you may even be tempted to skip the gym that day.”


Avocados contain all sorts of wonderful nutrients. They also contain fiber and fat, aforementioned no-nos in pre-workout foods. Instead, save the green power food as a part of your post-workout replenishment, its B vitamins, minerals, and healthy fat are just what a recovering body needs.