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Recently, there has been lots of advice on social media suggesting working out in a fasted state to improve weight loss and the quality of workouts. Our body goes through different “states” throughout the day in which it utilizes different energy sources. A fasted state is a state that our body is in after not eating for 14-18 hours. Today, we’ll be exploring this and whether working out in a fasted state is right for you. 


There are a lot of contradicting studies on whether working out on an empty stomach (skipping breakfast to be in that fasted state) is actually better for weight loss. One reason why weight loss may occur in a fasted state is because our body likely relies on fat stores for energy in this state, with no glucose from food coming in. The controversy comes in when looking deeper into the research being done. Some studies say that working out fasted can lead to a lower caloric intake throughout the day, which can ultimately lead to weight loss due to caloric restriction along with an increased caloric expenditure. On the other hand, many studies saw no differences in weight loss whether participants were fasted or not. Nutrition is definitely a complex topic, and even professionals don’t always have a blanket answer. It ultimately comes down to what makes you feel best, and what is the most sustainable for yourself. Below are some guidance for whether trying a fasted workout is ideal for you. 


Do you want to lose weight? 

  • Working out fasted may work for you, but ensure that you do eat after your workout to prevent muscle breakdown 
  • Monitor how you feel during and after your workouts to determine if it is sustainable for you and your body 


Are you wanting to build muscle? 

  • Working out fasted when trying to build muscle likely will not help you meet this goal
  • Your body needs enough fuel from your food to build protein in order to build muscle mass
  • It’s essential to eat food with carbohydrate and small amount of protein before your workout (such as greek yogurt, peanut butter and toast etc.) to fuel your workout, and to eat protein sources after your workout 


Are you doing high intensity workouts? 

  • If you are doing workouts that are high intensity and require lots of energy, it is best to fuel yourself well before a workout than to do it fasted
  • Glucose (carbohydrates) is a great quick source of energy that our body likes to utilize for these types of workouts, and glucose will not be used if our body is in a fasted state


Do you have any pre-existing health conditions? 

  • For example, those with low blood pressure or blood sugar should not work out fasted to prevent injury and further complications 


Tips for working out fasted: 

  • Do lower intensity workouts (Ex. swimming (short length of time), resistance training, pilates, yoga, walking) 
  • Drink water during the workout to ensure you’re still hydrated 
  • Do shorter workouts while fasted 


All in all, there’s no clear cut answer as to whether fasting before a workout is beneficial for weight loss. The most important thing is to continue to live a healthy lifestyle (working out or exercising at all is still good whether fasted or not, to continue building and maintaining a healthy relationship with food, and to do what makes you feel good and is right for your body. Additionally, ensuring that meals after a workout is filled with lots of protein and other macronutrients to help you maintain muscle mass and to help you feel your best. Don’t be afraid to reach out to a registered dietitian for more tips and guidance. Also, don’t forget — you might not need to lose weight to be healthier — seek a dietitian to discuss your relationship with food if you want to learn more about what your body really needs!