Two groups of obese men participated in a six-week endurance training program as part of the study. Each group committed to five weekly cardio sessions and consumed the same foods. Is that the only distinction? One group worked out prior to breakfast, and the other went to the gym one hour following breakfast.

Body Mass Index (BMI), Body Fat Percentage, and Waist Circumference measurements showed no appreciable variations in fat reduction amongst the groups.

By making the body rely on its own fat reserves for energy throughout the activity, the study has refuted the widely held belief that fasting cardio promotes greater fat loss.

This misconception stems from a confusion between adipose tissue loss and adipose fatty acid oxidation, two different processes that burn fat.

Adipose fatty acid oxidation, or burning fat for energy, is essential for working out while fasting. Nevertheless, unless your activity causes a more severe energy deficit, it does not aid in the loss of body fat, or adipose tissue.

In order to function, our bodies need energy from a variety of sources, including fats and carbohydrates. For example, your body will have to restore 300 kcal of glycogen, which is stored carbs. It is not possible to store this energy from carbohydrates as fat.

Consequently, the overall energy balance, or the difference between energy intake and energy expenditure—a calorie deficit—determines the entire net energy loss, regardless of the energy substrate that your body burns.

These findings are corroborated by a 2017 meta-analysis that revealed both fasting and fed exercising effect fat mass loss equally.

Although doing cardio while fasting may be a personal choice, it is best to practice high-intensity endurance exercise and weightlifting after consuming carbohydrates to prevent any negative effects on your performance and, as a result, energy expenditure.

Before you hit the gym, fuel up for your next training session with one of these pre-workout vitamins.