Though many people understand that exercise builds muscle and that such growth occurs in the hours and days following a workout, fewer people understand the role food plays in that process. Food fuels one’s workout by supplying energy and by providing important nutrients to various organs and systems that are most impacted by exercise.

Because our bodies burn a lot of energy-providing nutrients when working out, we need to replenish them after. The American Heart Association notes that when we exercise, our bodies especially burn through many carbohydrates – “the main fuel for your muscles.”

In addition to replenishing, we also need food to help prevent injuries and to repair and rebuild muscle tissue that has been damaged or stressed during our workout. “Failure to eat the right foods or replace fluids after exercising will ultimately lead to an energy deficit and difficulties in recovery,” says Dr. Matthew Anastasi, a consultant within the division of sports medicine department of orthopedics at Mayo Clinic in Arizona.

What to eat after a workout:

Because of this, one’s dietary objectives following a workout should be replenishing lost nutrients and eating foods that aid in muscle recovery, says Caroline Susie, a registered dietician and national spokesperson for the Academy of Nutrition and Dietetics. She explains that eating carbs refuels lost energy and “replenishes lost glycogen stores” that the body has tapped into and used during one’s workout. The body’s glycogen stores are a form of glucose stored in one’s muscles and liver tissue that the body uses after more readily available glucose has been depleted during exercise.

Good sources of healthy carbohydrates to replenish these stores include fruits and vegetables, whole grains, beans, potatoes and sweet potatoes, lentils, brown rice and oats. Replenishing liquids lost through exercise-related sweating is also important. Drinking plenty of water and even blending water with 100% fruit juice not only helps with hydration but can also aid carb replenishing.

In addition to getting plenty of carbs after a workout, it’s also important to consume healthy sources of protein, says Barbara Olendzki, associate professor of population and quantitative health sciences at UMass Chan Medical School. “Whole fruit and protein can provide antioxidants to help with muscle repair,” she says. “Be sure to also have good fats like fish, lean proteins, legumes, avocado, and eggs, and avoid or limit bad fats such as cheeses, high-fat dairy, and fatty meats,” she says. As one such example she suggests an omelet consisting of eggs, spinach, tomatoes, onions and avocado, plus a side of fruit – a meal she says will both replenish carbs and get some recovery protein into one’s diet.

Susie similarly stresses the importance of eating protein after a workout along with carbohydrates. “Protein helps your body repair, rebuild and recover faster,” she explains.

What not to eat after a workout:

As important as it is to eat the right foods following exercise, it’s also vital to avoid the wrong ones. “Sugary foods and drinks and foods high in saturated fats or hydrogenated oils should be avoided,” says Olendzki. She also suggests ditching nutrient-empty fare like junk food and fried food, plus overly processed items. “These foods will inhibit muscle building and increase soreness,” she says.

On the practical side, Leslie Bonci, a registered sports dietitian for the Kansas City Chiefs and founder of Active Eating Advice, says that eating dry foods after a workout may also be ill advised because exercise can dry out one’s throat, making dry foods a bit harder to swallow. “Some people find acidic foods don’t sit well post exercise either, but this is an individual response,” she explains. “And drinking carbonated beverages after working out can cause bloating and a premature feeling of fullness,” she adds.

Should I eat immediately after a workout?

Knowing when to eat after workout can be as helpful as knowing what to eat. Olendzki suggests waiting to eat 30 minutes following a workout in order to “avoid cramps and malabsorption.” She also says that when working out hard, “digestion is compromised, so only easily digestible foods are well tolerated.” Such foods include bread, oatmeal, rice, bananas, applesauce, eggs, chicken and salmon.

At the same time, it’s important not to wait too long after working out either to ensure you gain the aforementioned benefits of replacing glycogen stores and rebuilding muscle tissue. Mayo Clinic suggests eating within 2 hours after exercise and to eat a snack if your next meal is further than 2 hours away. Bonci echoes similar advice: “Don’t wait too long to refuel as that will delay repair and recovery.”