From: hubermanlab
The topic of fat loss is both complex and extensively debated, yet it often boils down to a simple principle: balance between calories consumed and calories expended. However, exercise has an influential role in enhancing this equation not just by burning calories during the activity, but also by affecting metabolic processes post-exercise through specific nervous system pathways influencing fat metabolism. Here, we explore science-backed strategies as discussed by Andrew Huberman on the Huberman Lab Podcast focusing on how different forms of exercise can optimize fat burning as a tool for fat loss.
The Role of Intensity and Type of Exercise
Dr. Huberman distinguishes exercise intensity and categorizes it into three primary types:
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High Intensity Interval Training (HIIT): Defined as submaximal bursts of activity (80-100% VO2 max) lasting between 60 to 240 seconds interspersed with less intense recovery. This style increases heart rate and stimulates post-exercise oxygen consumption, leading to greater fat oxidation post-exercise ([01:13:12]).
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Sprint Interval Training (SIT): Consists of very high intensity exertion (greater than 100% VO2 max) lasting 8 to 30 seconds, followed by recovery periods. The extreme intensity of SIT makes it effective for rapid mobilization of energy stored as glycogen and may contribute to increased fatty acid oxidation (>89:00[01:11:22]).
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Moderate Intensity Continuous Training (MICT): Also known as steady-state cardio, which is performed continuously for 20 to 60 minutes at moderate intensity. This form mainly engages slow-twitch muscle fibers, efficiently burns fat during the exercise, predominantly targeting fat as a fuel source ([01:12:01]).
Timing and Nutritional State
Research highlights the impact of exercising in a fasted state versus fed state for fat oxidation:
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Exercising in a fasted state, particularly during high-intensity workouts followed by moderate-intensity exercise, enhances the proportion of fat burned, especially if this occurs after a glycogen-depleting workout ([01:21:02]). This is closely linked to the roles of fasting and eating schedules on metabolism.
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For moderate-intensity exercise lasting longer than 90 minutes, those who do not consume food beforehand will burn more fat past this point compared to those who have eaten ([01:17:07]).
Non-Exercise Activity Thermogenesis (NEAT)
Beyond structured workouts, non-exercise activity thermogenesis (NEAT), which includes subtle movements like fidgeting, has a significant impact on daily caloric expenditure. Dr. Huberman notes that fidgeters can burn 800 to 2,500 extra calories per day contributing to stress management. These movements also stimulate nervous system pathways that promote fat oxidation akin to more traditional forms of exercise ([00:36:06]).
Post-Exercise Fat Burning
An often overlooked aspect is the post-exercise energy expenditure. High intensity and high effort workouts increase post-exercise metabolic rate substantially more than low-to-moderate intensity sessions. This means that although more carbohydrates may be burned during the workout, fat oxidation post-exercise is heightened, contributing to overall fat loss ([01:25:01]).
Key Takeaway
Engaging in high-intensity exercise followed by moderate or low-intensity activities while fasting, and incorporating non-exercise induced thermogenesis-like fidgeting, can enhance overall fat burning efficiency through structured protocols.
Conclusion
The science of exercise for fat loss is not solely about the calorie burn during the activities but also about timing, intensity, and leveraging the nervous system’s role in metabolism. By integrating these exercise strategies based on scientific principles, individuals can potentially amplify their fat loss efforts more effectively. Whether through adapted workout routines or increasing day-to-day movement, these strategies can bolster fat oxidation processes significantly.