The number of calories burned during one hour of weight training is not a fixed figure but a highly variable estimate tied directly to the intensity of the session and the individual’s body size. Weight training, also known as resistance training, involves moving muscles against a force provided by weights, resistance bands, or body weight. While a single hour might not match the immediate calorie burn of sustained cardio, resistance work triggers unique physiological responses that contribute to total energy expenditure long after the session is complete.
Baseline Calorie Expenditure During the Hour
The most reliable way to estimate the energy used during a 60-minute weight training session is by using Metabolic Equivalent of Task (MET) values, which measure the energy cost of an activity relative to rest. Moderate-intensity resistance training, such as traditional sets with 60 to 90 seconds of rest, is often assigned a MET value of around 3.5. A person weighing approximately 150 pounds (68 kg) engaging in this moderate lifting for one hour would burn roughly 233 calories.
If that same 150-pound person increases the intensity to a more vigorous level, characterized by heavier weights, shorter rest periods, or complex movements, the MET value can increase to 6.0 or higher. At this vigorous intensity, the caloric expenditure for the hour would rise significantly, reaching approximately 400 calories. For a larger individual, such as one weighing 200 pounds (91 kg), the energy required to move their body mass and the weights is greater. A 200-pound person performing a vigorous 60-minute session would expend closer to 533 calories during the workout itself.
Key Factors Influencing the Burn Rate
The primary driver of calorie expenditure is the individual’s body weight, since moving a greater mass requires more mechanical work and therefore more energy. Heavier individuals naturally burn more calories than lighter individuals performing the exact same workout at the same perceived intensity. The effort needed to move the body and external load is proportional to the total mass being moved.
The second factor is the effort level, quantified by the percentage of one-rep maximum (%1RM) used and the length of the rest intervals. Lifting weights closer to one’s maximum capacity with minimal rest pushes the body to work harder, demanding a higher oxygen uptake and subsequent calorie burn. Existing muscle mass also plays a role in the total energy demand of the session. More muscle tissue is metabolically active, meaning a person with a higher percentage of lean mass can sustain a higher workload throughout the hour.
Understanding the Post-Workout Afterburn Effect
A significant advantage of weight training over steady-state cardio is the sustained energy expenditure that occurs after the workout, known as Excess Post-Exercise Oxygen Consumption (EPOC). This “afterburn” is the body’s physiological process of returning to homeostasis following the stress of intense exercise. The body needs additional oxygen and energy to repay the oxygen debt accumulated during the workout.
The energy expended during EPOC is used for several restorative processes, including replenishing energy stores, re-oxygenating blood and muscle tissue, and repairing microscopic muscle damage. Highly intense resistance sessions that involve heavy lifting or metabolic work maximize this effect, leading to a more pronounced and longer-lasting EPOC. While the immediate post-exercise EPOC may only contribute a small number of calories, the elevated metabolism can persist for 24 to 72 hours, adding a considerable amount to the total daily caloric output. This extended recovery period is what makes weight training an effective strategy for long-term body composition changes.
Structuring Your Workout to Maximize Caloric Output
Maximizing the caloric output within the 60-minute session depends on increasing the amount of work performed and minimizing rest time. One highly effective technique is to prioritize compound movements, which are exercises that engage multiple large muscle groups simultaneously. Lifts like squats, deadlifts, bench presses, and rows recruit more total muscle mass, demanding a higher energy cost per repetition compared to isolation exercises.
Furthermore, the duration of rest between sets is a direct variable that can be manipulated to increase energy expenditure. Minimizing rest time keeps the heart rate elevated and maintains the body in a state of high energy demand, shifting the session toward a more metabolic style of training. Incorporating techniques like supersets (two exercises performed back-to-back with no rest) or circuit training forces the body to sustain a greater output. These adjustments push the workout toward the vigorous intensity range, ensuring the highest possible calorie burn during the hour.