If you're a morning workout person (you go, Glen Coco), you've probably faced the question of whether you should eat something before exercising, or to work out on an empty stomach.
Often fasted workouts are done by accident (that is, you've hit the snooze button right up to the point where you have to rush to make your gym class), but many people deliberately use this method in the hopes of greater weight loss and muscle gain.
But do fasted workouts actually work?
"It has been hypothesised that performing aerobic exercise when fasted forces the body to rely on using fat as a substrate rather than carbohydrates, thereby reducing body fat to a greater extent than exercising after food consumption," Robbie Clark, dietitian and sports nutritionist, told The Huffington Post Australia.
However, for those wanting to primarily build muscle mass -- rather than to only lose fat -- Clark said fasted workouts may be effective.
"In regards to training for building muscle, a fasted state has been shown to increase growth hormone release, which helps the body make new muscle tissue, as well as burn fat and improve bone density," Clark said.
This alone might be enough to make some people want to try this method of training. However, as with anything regarding exercise and diet, it's not a one size fits all -- fasted workouts may work for some but not for others.
"It's important to note that everyone's circumstances are different," Clark told HuffPost Australia.
There is more than just one factor of fasting that plays a role in someone's ability to lose fat mass or build lots of lean muscle. Things like your environment, your genes, hormones, sleep hygiene, stress, diet and exercise program all play a role.
"When deciding on the best type of training that is most suitable to you, it is pivotal to include your health professional, trainer and GP."
If fasted workouts do happen to be the right method for you, Clark recommends the following tips.
1. Stay hydrated
"If you train in the morning and are wanting to try the fasted training method, it's important that you are well hydrated," Clark said.
"Overnight, your body is prone to dehydration, which may impact negatively on exercise performance. Consuming water is a great way to remain hydrated and still follow the principles of fasted training."
2. Ease into it
If you're used to having a big meal before your workout, start by reducing the size of your meals or snacks so as not to shock your system.
"Some people may find training on an empty stomach tough, especially at first. It may take some time getting used to and it depends on the type of training you are doing, as well as your base nutrition," Clark said.
If you're someone who has a very fast metabolism, you may need a little snack before your sweaty session.
"An option is to have a protein and fat based snack before training, or have sip on a protein drink during the workout. Branched chain amino acids (BCAAs) are also great for maintaining muscle mass, as they are used by the muscle for energy," Clark said.
3. Refuel properly afterward
Regardless of whether or not you exercise on an empty stomach, your post-workout nutrition is extremely important.
"It doesn't matter if your goal is fat loss or muscle building, your recovery or post-workout nutrition should be the most important focus," Clark told HuffPost Australia.
While your post-workout fuel depends on your exercise intensity, body size, body type and duration, Clark recommends the focus of any snack or meal should be on the composition of the macronutrients (protein, carbohydrates and fats), fluid and electrolytes.
"To guarantee you are replenishing your glycogen stores appropriately and supporting muscle recovery and growth, it is important to make sure your post-workout meal or snack is consumed within 30 minutes of completion and contain at least 15-25 grams of quality protein (more is required if the recovery snack consists of plant-based protein) and approximately one gram of carbohydrate per kilogram of body mass," Clark said.
Clark's top picks for post-workout snacks and meals: