Wellness Wednesday: The Muscle Myth: How Building Lean Muscle Affects Your Metabolism
When I first started in the fitness industry over a decade ago, one of the most common ideas taught to us was that adding 10 pounds of muscle could help you burn an extra 500 calories per day, leading to a one-pound fat loss each week without any additional changes. It sounded too good to be true—and as it turns out, it was. For years, I believed and even taught this until I dug into the research and found that the truth about muscle mass and metabolism is far more nuanced.
This myth has been passed around in fitness circles for years, giving people false hope that building muscle alone would be the magic key to shedding fat. But today, let’s dive into what the science really says about the connection between your metabolism and muscle mass, and break down how building lean muscle truly affects fat loss.
How Many Calories Does Muscle Really Burn?
For as long as many of us can remember, there’s been this widespread belief that gaining 1 pound of muscle would result in burning an additional 50 calories per day. Sounds like an amazing deal, right? Gain 5 pounds of muscle, and voilà, an extra 250 calories burned daily just by existing, amounting to about one pound of fat loss every two weeks.
Unfortunately, the real numbers don’t quite live up to the hype. Studies have shown that each pound of muscle burns approximately 6 calories per day, not 50. While that’s certainly better than fat, which only burns around 2 calories per pound, the metabolic boost from muscle is significantly less dramatic than many have believed.
So, is building muscle still worth it for metabolism’s sake? Absolutely! However, the key is understanding that muscle’s impact on metabolism extends beyond this calorie-burn myth.
Does Building Muscle Improve Your Metabolism?
The relationship between muscle mass and metabolism is more complex than just how many calories a pound of muscle burns. The real magic lies in the process of building and maintaining muscle.
Strength training and metabolism:
When you lift weights or engage in resistance training, you’re not just burning calories during your workout—you’re setting off a cascade of metabolic processes that continue long after you’ve put down the weights. Research suggests that resistance training can elevate your metabolism for up to 48 hours post-workout due to excess post-exercise oxygen consumption (EPOC), also known as the “afterburn” effect.
But here’s the kicker: up to 90% of the total calories burned from weight training may happen after you finish your workout, not during. This means that while muscle alone doesn’t torch calories at the rates many of us hoped for, the effort it takes to build and maintain that muscle does boost your overall calorie burn.
Muscle’s Role in Fat Loss
While the extra calorie burn from muscle mass might not be as high as we once believed, the benefits of building muscle go far beyond metabolism alone.
Fat vs. muscle during weight loss:
In studies comparing people who did cardio alone, those who added weight training into their routines, and those who didn’t exercise at all, all groups lost weight, but the weight-training group lost about 40% more fat. That’s because when you’re dieting without weight training, you’re more likely to lose a combination of fat and muscle. Incorporating strength training into your routine helps preserve muscle, meaning more of the weight you lose is coming from fat stores.
Plus, building muscle improves insulin sensitivity, making your body better at processing carbohydrates and less likely to store them as fat. This metabolic change means your body becomes more efficient, handling food and calories differently as your muscle mass increases.
What Really Boosts Metabolism?
It’s important to remember that metabolism isn’t solely dependent on muscle mass. Your daily calorie burn, or total energy expenditure (TEE), comes from several factors:
Basal Metabolic Rate (BMR): This is the number of calories your body needs just to keep you alive—things like powering your heart, lungs, and brain. Your BMR accounts for 50-70% of your daily calorie burn.
Thermic Effect of Food (TEF): About 10% of your daily calorie burn comes from digesting and processing the food you eat. Protein, for example, has a higher thermic effect than carbs or fat, which is why higher-protein diets can support fat loss.
Physical Activity: This includes everything from walking to your car, fidgeting at your desk, and exercising. It makes up 20-40% of your daily energy expenditure, and the more muscle you have, the more you’re likely to burn calories during physical activities and workouts.
The Bottom Line on Building Muscle and Boosting Metabolism
The idea that adding 10 pounds of muscle will make fat melt away by increasing your metabolism by 500 calories per day is a myth. But the benefits of strength training, muscle growth, and metabolic health are far from insignificant.
Building muscle not only helps you burn more calories during and after your workouts, but it also improves your body’s ability to handle food, preserves muscle during fat loss, and gives you the tools to keep the weight off long term.
Takeaways:
Muscle burns about 6 calories per pound per day—not 50.
Resistance training elevates your metabolism for up to 48 hours post-workout.
Building muscle improves insulin sensitivity, helping you process food more efficiently.
While exercise isn’t the primary driver of metabolism, it’s an essential part of any fat-loss plan that focuses on long-term success.
Strength training is not just about burning calories; it’s about creating a body that works more efficiently, performs better, and sustains fat loss over time. Whether you’re trying to lose weight, maintain a healthy body composition, or simply get stronger, the benefits of muscle growth go far beyond the number of calories burned.
