October 7, 2021

Thinking of Fasting Before Your Workout? Read This First

Fasting has been a hot topic of science for some time. Research has shown a variety of benefits, from increased energy utilization to improved insulin sensitivity.

It doesn’t matter if you have a personal preference or just want to hit the gym early, it has become increasingly popular to exercise on an empty stomach.

Douglas Smith explains, “Some studies and research have shown that fasting can help you tap into your energy needs less from glycogen than from fat stores. In this instance, fasting is better for fat/lipid-burning utilization.”

According to the American Council on Exercise, exercising in a fasted state can help burn fat faster than if we have low glycogen storage. This is used for energy. This is good news for anyone looking to lose a few extra pounds.

Experts argue that lack of energy can reduce the intensity of workouts, negating any positive effects. Fasted workouts are more appropriate for people who have specific goals, dietary habits and prefer a faster workout.

Continue reading to find out all about fasted exercises, including when and what to eat, as well as the best times to do them.


  • Lori Russell MS, RD CSSD, CPT is a Swisse Wellness Consultant @HungryForResults.
  • Douglas Smith is the co-founder of True Nutrition and its CEO.

When is the Best Time to Workout Fasted, and For How Long?

Lori Russell says that fasting should be done between the last meal and the start of training. This makes morning sessions more practical. While you shouldn’t eat before your fasted workout, it is a good idea to drink a lot of water and take a multivitamin to prevent any nutritional deficiencies.

Fasted workouts are more efficient for people who don’t use energy for digestion. This means that they feel more energetic and can easily complete a 60 minute session. Smith says that it all depends on the definition of working out. A 30-minute run in the neighborhood or a 45-minute session at the gym will tap into different energy requirements. If a workout is ideal and involves a four-hour climb up a mountain, or something more strenuous than that, fasting might not be the best option. Perhaps it’s better to break your fast halfway through the workout to provide energy from the outside.

It is important to strike a healthy balance between burning calories and depleting your energy stores. This can lead to long-term damage.

How Long Should You Wait to Eat After a Fasted Workout?

Smith says that some studies and theories suggest that eating for 30 minutes or more will aid the body. This helps in absorbing nutrients better than eating whenever it is convenient. The act of exercising is a stressor on the body and creates an environment that requires food. Healthy foods can help to utilize the insulin spike when you break a fast. This will help to shuttle nutrients to the areas that are most in need, such as the muscles you have trained just minutes ago.

It is difficult to eat a healthy post-workout meal when you have a busy schedule and are often on the move. Smith says this is not necessarily a problem. Although many people swear by the 30-minute protocol it is a trial-and-error scenario for most people. Self-experimentation and experimentation are key to finding out if it is beneficial for you.

Who Should Avoid Fasted Workouts?

Fasted workouts are not suitable for everyone. It is important to know what is safe for you. Russell says that any adult who has a medical condition or is pregnant should talk to a dietitian before they start fasting.

Smith also advises that fasting is not suitable for people with a medical condition such as hypoglycemia or other metabolic conditions that could hinder their ability to exercise using energy sources other than food. The human body is a complex system and may require energy from food before undergoing a fasted workout. Some people will have to adjust to exercising with no food.

This does not mean that fasted training should be avoided, but rather that the body needs to adjust to the new format.

Which Workouts Are Best in a Fasting State?

Fasted workouts can be convenient and may help to direct the body towards a goal. Fasted workouts are not intended to produce immediate results, but they can be used to improve future adaptations and performance. Smith explains that a fasted workout will not feel good because your body lacks an immediate energy source. Shorter bursts of exercise work better in this situation, because our bodies naturally turn to fat for fuel when insulin levels drop.

These cardio bursts are high-energy and high-intensity. This makes them popular. Northumbria University’s study found that exercising in the morning with an empty stomach can help you burn as much as 20% body fat.

The study was made by the Journal of International Society of Sports Nutrition comparing fed and fasted aerobic exercise. It was on 20 healthy females with similar caloriesintake. They found no significant difference from the baseline.

Some science suggests that fasted training is not recommended for people who are trying to build muscle mass. This is because glycogen is more efficient than fat as a source of energy. It can also lead to a decrease in the duration of your workouts and shorter workouts with less impact. Smith suggests that you skip fasted workouts when you want to achieve high speed or power. Fasted workouts should be avoided when stress levels are high as it can cause disruptions in hormone balance.

While some studies have shown a positive effect on fat loss during fasted training, it is ultimately up to the individual to decide whether to do so.

What Should You Eat After Your Fasting Workout?

Some foods are better for our bodies than others, so don’t reach for sugary treats to get an energy boost.

Russell says that it is important to refuel after a workout in order to begin the process of rebuilding lean tissue and replenishing glycogen. This is especially true if the workout was performed fasted. A quick snack with a 3:1 to 4:1 ratio of carbohydrate and protein is best for an immediate refuel.

Others prefer a higher-protein source to break the fast. Smith says that although it is highly individual dependent, I find a meal high in protein and low in carbohydrate and fats to be the most beneficial. However, this could be the right time to eat the majority of your carbohydrate rich foods. Self-experimentation is key. It doesn’t matter what, it is important to eat the most nutritious foods, as the body is primed to receive these nutrients after stress.

Fasted workouts can be used to burn fat, increase cardio endurance, or get in a workout before the rest of the fitness trends. They may become your favorite workout routine after some trial and error. Try it out and let us know what you think.