Whether you should exercise before or after breakfast for weight loss depends on several factors, including your personal preferences, the type and duration of exercise, and your overall daily energy balance. Scientific research shows that exercising in a fasted state (before breakfast) can increase fat burning during the workout itself, but this does not necessarily lead to greater long-term fat loss compared to exercising after eating.
Fasted exercise means working out after an overnight fast, typically before breakfast. Studies have found that during fasted aerobic exercise, the body tends to burn a higher proportion of fat as fuel, a process called fat oxidation. This has led to the popular belief that fasted cardio is superior for weight loss. However, a systematic review published in 2017 found that although fat oxidation is higher during fasted exercise, this does not translate into significantly greater fat loss over time compared to exercising after eating[1].
One reason for this discrepancy is that the body compensates for the increased fat burning during fasted exercise by adjusting metabolism later in the day. For example, after eating, fat burning decreases, and people may reduce their overall daily energy expenditure, which can offset the fat burned during the workout[1]. This means that the total calories burned and the overall energy balance throughout the day are more important for weight loss than the timing of exercise relative to meals.
Regarding performance, eating before exercise can improve endurance and strength during longer or more intense workouts. For sessions lasting longer than an hour, consuming carbohydrates and protein beforehand generally enhances performance. For shorter workouts, the difference is less clear, and many people perform well whether they eat first or not[2]. Elite athletes typically avoid fasted training because they need optimal energy for performance, while amateurs are more likely to skip breakfast before exercise[2].
When it comes to strength training, limited research suggests that fasted weightlifting does not negatively affect muscle strength or lean mass gains. One 12-week study showed no difference in muscle or strength outcomes whether participants trained fasted or fed[2].
There are some potential downsides to fasted workouts. Some people experience hunger, headaches, or nausea, which can affect workout quality and lead to poor food choices afterward. Others report feeling more focused and energized when exercising on an empty stomach[2]. Therefore, individual tolerance and preference play a significant role.
From a metabolic health perspective, skipping breakfast regularly has been associated with increased risks of metabolic syndrome, hypertension, and impaired cholesterol profiles. Eating breakfast may stimulate metabolism and help regulate appetite throughout the day, potentially supporting weight management[3]. However, these findings come from observational studies and do not directly address exercise timing.
Experts generally recommend eating a small meal or snack containing carbohydrates and protein about 30 minutes to two hours before exercise to optimize energy and recovery, especially if the workout is intense or long[4]. However, if exercising before breakfast fits your schedule and you feel good doing it, it is not harmful and can still contribute to weight loss as long as your overall calorie intake and expenditure support it[2].
In summary, the key factors for weight loss are total daily energy balance and consistent physical activity rather than whether you exercise before or after breakfast. Fasted exercise increases fat burning during the workout but does not guarantee greater fat loss over time. Eating before exercise can improve performance and recovery, especially for longer or more intense sessions. Personal preference, how your body responds, and your lifestyle should guide your choice.
Sources:
[1] University of New South Wales, “Does ‘fasted’ cardio help you lose weight? Here’s the science,” 2025
[2] Futura Sciences, “Fasted cardio: the truth everyone’s been waiting for about this controversial method,” 2025
[3] Medical News Today, “Skipping breakfast may increase hypertension, high blood sugar risk,” 2023
[4] AOL, “Should You Eat Before or After a Workout? Experts Reveal the Truth,” 2025
