- Your actual body composition differs from the weight used in this calculation: These metrics are for a 180 lb person who travels 5 miles in 10,000 steps and burns roughly 100 calories per mile. So, if you only weight 120 lbs, then you’d really only burn about 300 calories over the same 5 miles. Also, if your stride is too short to travel 5 miles in your 10,000 steps (ie perhaps you’re a bit more petite than allows for long enough strides to reach your 5 miles), then you may also miss out on hitting your burned calories goal. Also, even at rest body composition can play a role in your metabolism with muscle burning 7-10 calories per pound per day whereas a pound of fat may only burn 2-3 calories per day. Thus, even if you hit the 500 calories from the 10,000 steps, you may still not see results if you have a higher fat to muscle ratio as your baseline metabolic rate (calories burned at rest) is slower. Also, as you lose weight, the amount of effort to burn the same calories in exercise increases while your basal metabolic rate decreases.
- Say you weigh exactly 180 lbs and your body composition exactly matches that of the test subjects. Intensity in your travel may also affect the number of calories burned. Walking at a 4mph pace (or a mile every 15 minutes) would put you on track for 500 calories burned. So, it takes roughly an hour and fifteen minutes of walking to burn those 500 calories. Say you increased your pace to 6mph (a mile every 10 minutes). You could look to burn 444 of those 500 calories in just 30 minutes, or with only 3 miles of effort instead of 5 miles. Add another 4 minutes of running, and you’d match the 500 calorie output in just 34 minutes instead of an hour and fifteen. Alternatively, if you walked more slowly than 4mph, then it would take a longer time to burn 500 calories, so you’d need to extend your walking time to reach your goal.
- Gender also plays a role in metabolism. For instance, following puberty, most men began to increase their lean body mass as testosterone levels increase, whereas for women, we don’t see such a surge in lean muscle as testosterone levels are naturally lower than for men. That being said, participation in activities, such as weight lifting, that increase lean body mass may cause a slight increase in metabolism
- Age can also play a role. As we age, we may begin to see a decrease in muscle mass over time. This can be due to participating in less weight-bearing and strength-training activity, dietary changes and also that maintaining lean mass may become a little more difficult due to simply being older. In addition to the loss of muscle mass from the changes listed above, the parts of the body responsible for metabolism begin to wear down. While staying active and paying attention to diet can help offset these changes, the bottom line is that the whole pizza you could eat without gaining an ounce at 20 will make you gain weight at 40.
- Speaking of diet, one of the biggest misconceptions about exercise is that once done, you can now eat whatever you want. You know the extra 500 calories you burned? Check out the number you’re putting back in your post-workout smoothie. Or in your post-workout splurge at whatever fastfood you might be treating yourself with. It’s so easy to “treat” yourself with more calories than you burned exercising, not too mention more vigorous exercise often makes us hungry, so we tend to eat more than when not exercising anyway.