This Is What Happens When You Don’t Eat After A Workout

Most nutritionists recommend eating something within 30 minutes after a workout. Your body, after using up its available energy, needs to be refueled. Specifically with carbs and protein—for energy and to repair the microdamage that exercise does to your muscles.

We’re all busy, though. And sometimes, fitting in a workout means squeezing it into a quick 30-minute window and then rushing off to the next obligation. If you don’t have a protein bar or other handy snack packed, getting those nutrients in may not actually happen. But if skipping a post-workout nosh becomes a habit, you risk sabotaging your fitness goals.

“Some people will just feel fatigue, and some people can get disoriented from low blood sugar,” Jennifer Beck, M.D., sports medicine specialist and pediatric orthopedist at UCLA, tells SELF. She also notes that ignoring post-workout steps that are essential for recovery, like proper nutrition, can contribute to overuse injuries. “We think a lot of overuse injuries happen when people are not replacing essential building blocks as readily as they should,” Beck says. This can especially become a problem if you’re doing heavy muscle-building activities and neglecting what your body needs to repair microtears and damage. Fixing those tears is how your body builds muscle; failing to do so puts your muscles at risk of further damage next time you work out.

Food also contains electrolytes, minerals our bodies need to keep the muscles and nerves firing correctly. “If you had a very sweaty workout, replacing calcium, salt, and potassium, all part of standard food consumption, is also very important,” says Beck. If you tend to get super sweaty, or you’re working out on a hot day or going for a long training run, you’ll lose some of these things in your sweat. “If you’re not able to immediately replace them, it can be devastating and damaging.” Dehydration and hypoglycemia (low blood sugar) can both set in quickly and make you feel disoriented or even pass out. In rare cases, lack of electrolytes can throw off the electrical impulses that keep the heart beating properly, leading to cardiac arrhythmia, or irregular heartbeat.

If you’re going to remember one thing, though, make it water. “Water is the most important building block you need after a workout,” Beck says. And during, for that matter. In the end, the one thing you really don’t want to skip is rehydrating to replace any water you lost through sweating.

Skipping a post-workout meal every once in a while isn’t a huge deal, but it should never become a habit. “You want to set yourself up for good patterns,” Beck says, because developing healthy habits is the easiest way to prevent burnout and injury. Exercise should be fun and bring you positive health benefits, not end in muscle tears or stress fractures. “Both hydration and nutrition are important parts of having healthy exercise habits.”