I previously detailed that cardio makes you hungrier, causing you to eat more calories and to have an overall net calorie gain. Let’s go through some more reasons why doing cardio (aerobics) for fat loss may not be the best approach:
1) It burns fewer calories than you think. So you got on the elliptical machine for 20 minutes and got all jazzed up because the computer readout showed that you burned 417 calories – whew! Well, the whole story is a little less favorable. First off, the computer (if you didn’t enter in your weight) is calculating calories burned from its data on “average user”, so if you’re not a thirtysomething 165 pound male, sorry – that’s not the real number. Secondly, the machine adds in EPOC and BMR to its totals, so as to maximize the number of calories burned.
What’s EPOC and BMR?
EPOC – Excess post-exercise oxygen consumption which is the additional oxygen your body takes in to “right itself” after an exercise bout. If we liken your muscles to a car engine, when you run a car engine, it continues to “burn hot” long after you shut off the ignition. This is akin to the increase in metabolism your body undergoes after performing an exercise bout. As a result of EPOC, you burn additional calories as a result of increased metabolic activity post-exercise.
BMR – Basal Metabolic Rate, which is roughly the number of calories your body burns at rest in order to maintain respiration, keep organs alive, i.e., keep your body alive and functioning.
You would have burned BMR anyway, regardless of whether or not you performed the exercise bout.
EPOC is valuable, but it can be increased far more via (ahem) strength training.
2) It burns much, much fewer calories than you think, actually. If you’re like most people, you do the same cardio at the same pace over and over again, day after day. Well, your body is quite adaptable and learns to do more with less; in other words, it becomes efficient at performing exercise. By becoming more efficient, you burn fewer calories as a result of doing the same workout.
If you began by running 3 miles in 25 minutes, it is likely you burned roughly 300 calories (not including EPOC and BMR – contrary to what Dr. Warden says, I am not a machine:) ).
If you are still running that same 3 miles 6 months later, when you’re more fit, it’s likely that you are burning far fewer calories – probably somewhere around 200 calories or so.
If you continue to run the same 3 miles, you will burn fewer and fewer calories as your body adapts further to the workload.
This is not an acceptable scenario for fat loss purposes.
What can one do?
Well, I’m partial to having clients not do cardio at all for the reasons outlined in the last two posts. However, some clients have extremely sluggish metabolisms, and to jumpstart it, I’ll have them perform intervals in the Tabata style (modified to make it slightly easier, of course). The important thing is that the workloads increase over time to counteract this adaption effect.
So there you have it. Ok, I’m going back to eating; I mean, “fueling up.”