Some self-proclaimed exercise experts on social media swear that working out on an empty stomach burns more fat.
But it is a common misconception that exercising in a fasted state improves performance or burns more calories, says Abby Langer, a dietitian in Toronto, Canada.
"The research shows that in terms of gains, it doesn't really make much of a difference," she says.
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Does that mean you should load up on protein and carbs right before a workout? No, that is not true either. Here is a look at when - and how - you should eat before, after or even during a workout. And remember, experts say what you eat is more important than when you eat.
What is the case for eating before exercising?
The calories in food are energy, so you need them to fuel your body for a proper workout. Eating too much too soon beforehand, though, can be problematic.
Exercising diverts blood from organs including the stomach to the muscles, says Langer, author of Good Food, Bad Diet . So exercising on a full stomach affects the digestive process, which could cause cramping or even make you feel sick.
That is particularly the case with meals high in fat, protein or fibre, which take longer to digest than carbohydrates . Langer recommends eating a high ratio of carbs beforehand and waiting two to three hours before intense exercise.
"You don't want to eat a big steak an hour before you play hockey," she says.
If you exercise first thing in the morning or before dinner, it is OK to have a carb-rich snack like a banana with peanut butter or yogurt with fruit beforehand. It will give you the energy to perform well, and you can fuel up afterwards with a full meal.
When, and what, should you eat after exercise?
That steak may serve you better after exercise, because that is when a higher ratio of protein is easier to digest, says Krista Austin, a physiologist in Colorado Springs in the US state of Colorado.
Austin says that, if after a workout you are going to have to wait over an hour for a full meal, enjoy a protein-rich snack in the meantime to curb your appetite.
"A lot of people get very hungry about an hour after exercise, and you don't want to do that," says Austin, co-author of Performance Nutrition: Applying the Science of Nutrient Timing . "You want to catch it early, or you go and overeat."
But it is another myth that you need to grab a protein shake within minutes of finishing to build the biggest muscles, Langer says.
Many exercise enthusiasts point to what is known as an "anabolic window" of about an hour within exercising that the body is primed to repair muscle .
For the average person, you have a much longer window, and nutrient timing is less important than making sure you consume some protein at every meal, Langer says.
The body needs a continuous supply of amino acids such as protein for muscle repair and maintenance, she says, which means about 25 to 30 grams every meal, depending on various factors.
"Prioritising that will help with goals, either muscle building, satiety, weight loss, all of that," Langer says.
How about eating during exercise?
Most people who are eating enough throughout the day do not need anything during a workout.
Langer and Austin say the threshold is about an hour of intense exercise. Longer than that - say you are training for a marathon - And you could gain an advantage from having a carbohydrate-heavy snack mid-way through.
Rather than concentrating on meal timings, Austin advises paying attention to what and how much you consume. She warns against making the subject too complicated and suggests adhering to the U.S. Department of Agriculture’s MyPlate guidelines. www.myplate.gov - suggestions for maintaining a well-balanced diet.
What we really need to educate people about is how straightforward proper nutrition can be," she states. "Perhaps it’s best to shift away from concentrating on nutrient timing and instead ensure consistent meals throughout the day with an emphasis on overall wellness.
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