Many people grossly over-estimate how many calories they actually burn during a workout. Unfortunately, I think this tends to be one of the biggest fallacies when it comes to weight loss.
We can elaborate on this later, but the truth is, even the craziest of fitness nuts only burn, at most, 30% of their daily calories working out on a given day. I know of lots of individuals who use heart rate monitors, calorie counters, pedometers, etc. to give them a ball park figure of how many calories they burned, and that's great, but these gadgets are very much a guess at best. At the end of the day, exercise improves your body to run more effectively and efficiently (burning calories along the way), but exercise and what you eat (diet - although I hate that word) is what is going to be most effective for weight loss.
Most of our calories burned on a day to day basis come from doing things like digesting food, thinking, breathing, repairing a cut to your leg/face from shaving, etc. This is known as our resting metabolic rate, which means you are burning a ton of calories even when watching tv. There are other daily activities can also contribute to our daily caloric expenditure that are known as non-exercise thermo-genesis (N.E.A.T.) such as walking up the stairs, gardening, walking your dog, etc.
A well-rounded exercise program improves your body. An elevated heart rate for an extended period of time (most people call this "cardio," although I am not a big fan of that term either) improves the efficiency of your heart and lungs to transport oxygen from the air to your muscles to create energy.
Resistance training causes a stimulus for your muscles to adapt in some way.What's great about resistance training is that it tends to not only burn calories long after your workout is over, but it also signals your body to retain the muscle you have when losing weight through dieting at a caloric deficit - eating less than you burn (more on that later). If you are trying to gain weight (muscle), resistance training stimulates the body to build muscle with the excess of calories that you ingest (again, more on that later).
To summarize; cardiovascular exercise (elevated heart rate for a set period of time) improves the efficiency and effectiveness of your cardiovascular system which includes your heart, lunges, arteries, and veins. This is beneficial because if the inner plumbing of your body can transport nutrients and molecules efficiently and effectively, the better your overall health.
Resistance training improves the strength of your bones, connective tissues, and muscles. On top of that, resistance training promotes hormonal adaptations that signal your body to maintain as much lean body mass (muscle) as possible. Our bodies really do follow a "use it or lose it" mentality, so if you aren't training the structural framework of your body then you will see signs of atrophy and decay. This is especially important as we age.
When it comes to exercise, the way I see, as long as you are moving your body and challenging yourself...truly challenging yourself, then you will burn calories. Everyone should include both main "types" (cardiovascular and resistance training) for optimal health and effective body composition management. Obviously some folks delve deeper into one type or another (marathon runner vs. powerlifter), however for the general population, a good mix of the two will keep you strong and healthy. Having said all of that, when it comes to weight loss/gain, exercise only takes you so far and what you consume is going to need to be something that is just as important, if not more important to focus on.
Tyler Robbins B.Sc. CSCS
Director of Fitness
Head of CrossFit