Q: I walk on a treadmill daily and for example, I burn about 300 calories and 90 fat calories in a 30 minute period. What is the difference in regular calories and fat calories? Or do I combine both numbers for total calories burned? Thanks for your help.

A: I think most treadmills already count the 90 in the 300, so you only need to look at 300. BUT you should know that the 'fat calorie' count is completely meaningless and even the total calorie count is a double-edged sword.

The fat calorie count is supposed to show you how many calories are burned using the energy from your muscles' fat stores. Even assuming that number is correct, it's meaningless because your muscles' fat stores do not function in isolation from the rest of your body and most certainly do not have a direct one-to-one relationship to your body fat levels. If you use the energy from the fat stores, then you have more energy left in glycogen stores (i.e. 'carb' stores) so you have less incentive to burn fat in the future. Any claim that an exercise 'targets' only your fat or a only specific area of the body (such as waist) is false.

The best analogy I can offer is how your taxes are 'burned' to educate your kids. Does every school tax dollar you contribute goes towards educating ONLY your kids? No, of course not! The tax revenue distribution system is far more complicated than that. However in the end, your kids and all the other kids do get their fair (or not so fair :) chunk of the education money. Similarly, does every other calorie (or 90 out of 300 or whatever) burned directly decrease fat levels? No, absolutely not. Your fat levels may well decrease in the long run, but the reasons for that decrease are far more complicated than what your treadmill tries to tell you.

Now, why did I say the total calorie count is a double-edged sword. Again, because people fall into a mistake of assuming that every calorie burned comes from fat. This is also wrong and understanding why it's wrong should reinforce even more the ridiculousness of the 'fat calorie' estimation. If you are losing weight (and most people doing cardio are in fact trying to lose weight), then your body will burn BOTH your body fat and body muscle tissue for calories. Your body's fat is the natural energy store meant for this very situation -- o making up the energy that's missing in the food intake. However your muscles can ALSO be burned for energy and from your body's point of view muscles may be the more desirable fuel because by burning the active metabolic muscle tissue your body not only gets some energy right away but also LOWERS its future energy demands. This is because muscle tissue requires energy just to maintain itself. So, less muscle tissue means less energy needed to maintain the body means less food needed. This way your body responds to your cutting the food intake by cutting unessential energy consumer in muscle tissue.

Why is losing muscle tissue bad? Well, for one if your body burns muscle tissue for some number of calories it means it's not burning fat for those same calories. But a much worse problem is that your muscle tissue metabolism is BY FAR your best friend in losing fat. So as you burn muscle tissue for energy, you're losing more and more of your fat-burning potential. Furthermore you're lowering your metabolism which makes you more vulnerable to future fat gains. And on top of all that, you become weaker and lose muscle tone.

So now hopefully you see why all those calories burned during cardio may be a double-edged sword. Does it mean cardio is evil? NO! Cardio is absolutely great for your health! But it is not the great fat-burner it's advertised to be, especially if you don't have that much fat to lose in the first place. A much more effective approach is to focus on a good diet and a good weighttraining program and only supplement those with moderate amounts of cardio. You can read this article to learn how to put together a good complete fat-loss program.