Thanks for all your emails on my blog post refuting John Cloud’s Time magazine article that exercise is useless for weight loss. Several of you pointed out, however, that I neglected to mention the author’s contention that exercise is supposed to turn fat into muscle. You’re right, I should have. My bad.
In case you missed it, here is the quote from Mr. Cloud:
You might think half a muffin over an entire day wouldn’t matter much, particularly if you exercise regularly. After all, doesn’t exercise turn fat to muscle, and doesn’t muscle process excess calories more efficiently than fat does?
It amazes me that a high-profile journalist would print such an absurd statement and it’s even more amazing that the fact-checkers over at Time wouldn’t have flagged it as an obvious faux pas. Let’s be clear here: muscle and fat are two separate and distinct properties that have completely different molecular structures. Muscle is a protein-based tissue comprised of filaments called actin and myosin. These filaments are derived from various amino acids and carry out a plethora of metabolic functions. Body fat, on the other hand, is a stored triglyceride. Triglycerides are made up of a carbohydrate (glycerol) moiety and three fatty acids. Once formed, triglycerides are packaged into cells called adipocytes (fat cells) and are used primarily as a long-term energy source. In their stored form, fat is biologically inert with little purpose other than to provide fuel and insulation. Hence, the possibility of muscle turning into fat (or vice versa) is akin to an apple becoming an orange: There’s simply no mechanism for it to happen.
On a related note, this shows that you shouldn’t avoid strength training in fear that the muscle you develop will turn to fat if you stop working out. Sadly, I still hear this reasoning, especially amongst women. Reality check: The only thing that happens when you stop training is that your muscles begin to atrophy (i.e. get smaller), eventually returning to pre-exercise levels. Since muscle loss is often associated with a decreased metabolic rate which, in turn, indirectly increases fat deposits, it can appear as if muscle has turned into fat. In reality, though, there is simply more fat and less muscle.
But why would you stop training, anyway? Make exercise a habit. Ingrain it into your everyday lifestyle. You’ll be healthier–and yes, leaner–as a result.