I have seen many people who come into the gym tired, frustrated and desperate. After hours and hours spent at the gym they are not seeing the results they want. I had one woman tell me she does three hours of cardio a day, yet her body fat percentage was still very high. I want to explain some of the reasons why someone who does tons and tons of cardio may be stuck in a fat-loss rut.
1. You think because you do lots of cardio, you get a free diet pass.
I always say it takes me 5 minutes to eat 500 calories of ice cream, but it takes me an hour of running to burn it off. I see this problem a lot with people who run often; usually they feel like since they are outputting so many calories in exercise everyday, it puts them in a position to eat whatever they want. For someone who loathes cardio (like myself), it's horrible to find out that all those hours on the treadmill were eclipsed by some really bad diet habits. I used to go out and eat all kinds of junk and justify it by saying "I worked out today, I deserve this". Not only was I eating all the calories I just burned off, but I was eating sugar and fat calories that usually came with my cardio "reward" meal.
2. You are exercising above your anaerobic threshold.
For every body, there is a certain amount of "work" that your body cannot handle. It doesn't matter what type of activity you are doing. Once you encounter a certain insensity in any exercise, you body will stop burning fat completely. Yes, you heard me. At that point you are burning 100% of your calories from carbohydrates. I'll say it again. YOUR BODY STOPS BURNING FAT. Unless you are an elite athlete, there is no reason to train at this intensity. If I got on an elliptical machine and went as fast and as hard as I could possible go for a full hour, I probably did nothing to help my body shed fat. The machine I used will tell me I burned a heck of a lot f calories, but if I haven't burned any fat calories then I'm not going to lose fat.
Many people, women especially, feel that if they just take off running and go as fast as they can, then fat loss will come more quickly. Believe me, this is one thing you don't want to do. You may see a drop in your scale weight the first week after beginning an intense training routine, but this is most likely due to water and/or muscle loss. You will have much more success if you slow down and stay in your target heart rate zones.
For example, at a heart rate of 112 bpm I burn about 7 calories a minute, with 5 of those calories coming straight from fat. At a heart rate of 170 bpm, I'm burning way more calories per minute (about 12) but I only burn 2 calories from fat. That means I would have to spend more than twice the time at a higher heart rate to burn the same fat calories that I would normally burn at a much lower intensity.
3. You are not eating enough.
If you are someone who does hours of cardio but doesn't consume enough calories during the day to support that level of activity, then your body will respond by lowering your metabolism. Your body needs a certain number of calories to function, and if you aren't eating enough to support a healthy, functioning body, AND you are exercising a great deal, it is very likely your fat loss will stop. This is your body's way of trying to keep you alive by holding onto all your fat stores.
If you are stuck in a rut, get yourself a heart rate monitor and have a cardio respiratory test done to determine your own unique fat burning zones. Once you know the heart rate where you are going t be burning the maximum amount of FAT calories, and if you consistently train in your zone, you will see the results you want. Start writing everything down that you are consuming so you can have a clear picture of your calorie intake, and remember to work smarter, not harder!