A recent study has challenged the prevailing belief that exercising on an empty stomach promotes superior fat loss compared to working out after eating. The research, conducted on two groups of obese men participating in a six-week endurance training program, revealed no significant difference in fat loss between those who exercised before breakfast and those who exercised after their morning meal.
Both groups adhered to a rigorous regimen of five cardio sessions per week and maintained identical diets throughout the study. Despite the variance in timing of their workouts, assessments of Body Mass Index (BMI), Body Fat Percentage, and Waist Circumference yielded comparable results, indicating no discernible disparity in fat loss between the groups.
Contrary to popular belief, the study refutes the notion that fasted exercise triggers enhanced fat loss by compelling the body to rely on its stored fat reserves for energy during workouts. This misconception arises from a misunderstanding of the two distinct mechanisms of fat burning: adipose fatty acid oxidation and adipose tissue loss.
While exercising in a fasted state may indeed prompt the utilization of fat for energy (adipose fatty acid oxidation), it does not necessarily translate to a reduction in body fat (adipose tissue loss) unless the exercise regimen results in a significant energy deficit.
It’s important to recognize that our bodies utilize various energy sources, including carbohydrates and fats, to fuel physical activity. If, for instance, you deplete glycogen stores (stored carbohydrates) during exercise, your body will prioritize replenishing these stores rather than storing excess energy as fat.
Consequently, regardless of the energy substrate utilized during exercise, the ultimate determinant of fat loss is the overall energy balance, i.e., the disparity between energy intake and energy expenditure—commonly known as a calorie deficit.
These findings are corroborated by a 2017 meta-analysis which concluded that fasted and fed exercising yield equivalent effects on fat mass loss.
While fasted cardio remains a personal preference for some, experts recommend consuming carbohydrates prior to high-intensity endurance training or weightlifting sessions to optimize performance and energy expenditure.
Before your next workout, consider fueling up with one of these pre-workout supplements to maximize your training potential.
