2 Experts Explain Why You Must Eat After a Workout (and What Happens If You Don't)

If you've just worked out, don't even think about skipping out on food. "During a workout, especially one involving strength training, you are breaking down muscle and creating small micro tears," Rebecca Gahan, certified personal trainer and owner and founder of Kick@55 Fitness in Chicago, told POPSUGAR. Immediately following the workout, your body needs protein to start the repair process, and if you're not eating within 30 minutes of working out, you might not be able to maximize nutrient absorption and muscle repair as well as you could, she explained.

According to Gahan, the best thing to eat after a quick shower and cooldown is a complete protein, which has all nine of the essential amino acids. "The closer the protein is to human tissue, the easier for the body to rebuild. So chicken, fish, lean beef, and eggs are ideal, with two ounces of protein for a female and four ounces of protein for a male," she said.

What can happen if you miss your window? A lot, actually. We broke down the two major ways — mentally and physically — your body is affected when you skip your post-workout snack.

If you're in a brain fog after your cycling class, you might be too low on glucose levels, as your body uses them when working out for energy, leaving you depleted afterward. Hence why many athletes look for ways to replenish electrolytes after a workout through complex carbs, proteins, potassium-rich foods, and sports drinks (you can even try one of these electrolyte snacks). To help offset lightheadedness, mental fatigue, or possible disorientation due to low blood sugar, Gahan recommends a banana with nut butter right after you finish your sweat session.

You also might lash out at those around you. Turns out that when you're in need of glucose, you can start to get "hangry," says Michael Wolfe, R.D. at the The Vitamin Shoppe. "If we deplete our glycogen stores, enter a hypoglycemic state, and then fail to take in an adequate amount of carbohydrates post-workout, there simply isn't enough glucose to maintain optimal brain function," he told POPSUGAR. And when the brain is out of whack, it can really impact your mood, thoughts, and alertness.

If you start to feel a bit faint and fatigued, it's not just because you crushed your workout. It's actually probably because you didn't refuel and repair as you should have. Gahan explains you might start to feel physically drained due to dehydration; your body lost electrolytes and water through all that sweat.

When your blood sugar levels are lower, you're at risk of hypoglycemia, which is low blood sugar. What's more, your workouts might suffer in the long term, as that low energy and insufficient repair will carry over into your performance, Gahan said. That means the micro tears that happened from the previous workout won't have time to repair for your next one. When muscles are weaker, you're also more likely to overuse them and get injured. In fact, you may experience cramping and muscle spasms, Gahan said, as lack of glucose and nutrients, which were depleted through your sweat, are responsible for proper muscle and organ function and endurance.

"There are also many nutrients, most notably B-vitamins, that are essential to energy production during exercise," she said, so eating well-rounded recovery meals is critical.

"I recommend simple carbohydrates mixed with a high bioavailable source of protein as soon as possible, followed by another well-balanced meal within two to four hours post-workout for optimal nutrient utilization," Gahan suggested. "This may include a whey protein mixed with milk or juice or a banana with peanut butter and a hard-boiled egg, immediately post-workout, followed by a meal that includes protein, carbohydrates, and fat from all major food groups."

If you're looking for a few protein smoothie recipes, here are a few high-protein choices that will aid in recovery. And when it comes to healthy recovery snacks, here are a few drool-worthy ideas.