The Biggest Fitness Myths, Debunked
Exercise What's inside?
Morgan Medeiros MSc
January 2, 2018

biggest fitness mythsMany myths have befallen the world of diet and exercise: muscle, in particular, has been the subject of multiple myths and arguments. We’ve got all the deets on two of the most perpetuating myths in the world of muscle, so that you needn’t wonder, google, or debate any longer. We’re taking on some of the most vicious myths underlying the world of muscle, fat, exercise, and fitness. Keep checking back as we continue to debunk the confusing world of fitness, lest you fall victim to the weight room fairytale of a fellow gym goer.

Myth: Muscle Weighs More Than Fat

Reality: Regardless of the substance, a pound is a pound is a pound—this is dictated by physics.

For example, one pound of feathers and one pound of bricks, are still both a pound, even though it takes a lot more feathers to achieve that pound.

However, fat does take up more space than muscle, as muscle tissue is more compact. That means that two individuals of identical weight and height standing side by side my look drastically different, thanks to body composition. In most cases, the individual with higher musculature will appear smaller than the person with more fat tissue.

Myth: Exercise Turns Fat Into Muscle

Reality: Muscle cannot turn to fat, and fat cannot turn to muscle. On a physiological level, fat and muscle are two different tissues- one cannot differentiate into the other.

If you lose muscle, the muscle itself has become atrophied, shrinking in size and strength. If you gain muscle, you have increased the strength and size of your muscle tissue.

How does the process work?

When muscles are subjected to intense, repeated exercise (for example, during a bout of exercise), small micro tears and trauma to muscle fibers sets the repair and recovery process into motion. Cell organelles (the “internal organs” of a cell) take note of the damage to existing musculature and send out specialized cells (known as satellite cells), to enter the site of the trauma.

Satellite cells act like a specialized repair team, fusing together damaged muscle fibers to form myofibrils (new strands of protein) or repair damaged proteins. As this process occurs over a period of time with consistent stimuli (exercise), muscle fibers increase in size and number.

So what happens when you lose fat?

If you lose fat, fat cells themselves have shrunk, not gone away entirely- your body retains the tiny, microscopic fat cells, and they will grow larger in the presence of a Caloric surplus, which is what occurs when you gain weight.


Myth: If you want to lose fat, you should do slow, steady state cardio.

Reality: You burn more fat by burning more Calories.

Whenever you exercise, you’re burning a mix of stored carbohydrate and fat. At a slow, steady rate of exercise (for example, walking), a higher percentage of fat is burned, explaining the origin of this myth. However, because of the low degree of exertion, fairly few Calories are being burned for that period of time.

As you exercise at a more vigorous rate, your body prefers more carbohydrate than fat, as the utilization rate is much faster. You’re also burning more Calories per period of time.

Remember, during both slow and vigorous exercise, your body is using a combination of carbohydrate and fat. So, if you exercise for say- 1 hour- and burn 600 Calories while exercising at a vigorous rate, and 200 exercising at a slow rate, the percentage of Calories burned from fat may be higher during slow, steady exercise, but the total number of Calories burned from fat will be higher during high intensity exercise.

Myth: Every pound of muscle burns 50 Calories a day.

Reality: Muscle burns more Calories than fat. But not as many as you think.

While it’s true that muscle does burn more Calories than fat, the contribution of muscle to your resting metabolic rate (the baseline number of Calories your body needs to maintain weight) is very small. The largest contribution to RMR is organ function, not function of skeletal muscle.

While fitness magazine, blogs, and pinterest posts love to proliferate the myth that a pound of muscle burns 50 Calories a day, a single pound of muscle burns about 6 Calories per day, while a pound of fat burns about 2.

So, let’s say a 160 lb individual were to gain muscle, reducing their body fat percentage from 25% to 20%.

That would amount to a muscle gain of 8 lbs, for a total of 32 extra Calories burned per day.

So why do super-lean athletes have such high metabolic rates?

Remember, athletes are exercising- vigorously and consistently, often for long hours. While most athletes are leaner than the average individual, it’s in large part due to their increased activity level that belies their high Calorie needs.

Morgan Medeiros is a certified nutritionist, holding a both a Bachelor and Master’s Degree in Clinical Nutrition. Morgan completed her undergraduate education at Central Washington University, and her graduate education at Northeastern University. During her time as a graduate student, Morgan focused her area of expertise in health education, weight management, and behavioral change. Morgan has experience working in areas of nutritional neuroscience and disease prevention, obesity prevention, and weight loss. Morgan also works in areas of nutritional analysis and menu labeling for restaurants, where she is able to creatively bridge her interest in food culture and health education. In her free time, Morgan enjoys traveling, reading, writing, running, and spending time with her family and friends (including- most importantly- her dog, Clyde).


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