Breaking Through the Plateau, 3

Weight loss goals tend to be one of the top considerations amongst members and clients. I often get asked about the “fat burning” zone on the cardio machines.

The Fat Burning Zone

To understand this, we must know how and where the body derives its energy (adenosine triphosphate or ATP) to do activities. There are three energy systems that provide ATP:

  • Phosphagen System - Pulls ATP-CP stored directly in the muscles for activities that are of high intensity and only last up to 10 seconds. This energy system can take up to five minutes to replenish. So, if activities last longer, the body will pull from another energy system.
  • Glycolytic System - Converts carbohydrates into ATP for activities of moderate intensity lasting up to 40s. This system takes up to two minutes to replenish. If an activity last longer, it will pull from another energy system.
  • Oxidative System - Converts fat into ATP for activities that are low in intensity and long in duration.
  • Tri System - Each energy system is always in use. The demand of the activity will dictate which one is the most used system.

So, when we hear “fat burning zone,” we are working at a level in which the body wants to use fat to convert to ATP (oxidative system). This means the “fat burning” workouts are very low-intensity, but long in duration.

There is a bit a “myth” involved in this concept. In exercise, the higher the intensity of the workout the more calories you will burn. When we do a “fat burning” workout the intensity is low, which means we will not burn a lot of total calories. If we do an intense workout we will burn more calories. While the percentage of fat being burned in a high intensity workout is lower than that of a lower intensity workout, the overall total of calories being burned from fat may be higher than that of the lower intensity workout.

For example:

“Fat burning” Workout - If a person does a 20 minute, low-intensity workout they may burn 100 calories, with 75% coming from fat. In this workout the person will burn 75 calories from fat.

"High-Intensity" Workout - Now, if this same person does a 20 minute, high-intensity workout they may burn 175 calories, with 50% coming from fat. In this workout the person will burn 87.5 calories from fat.

These numbers have been simplified for this example, but it does show that higher intensity workouts will burn more calories overall and more calories total from fat. Then the question is “what should I do”? The answer is simple: both. On days you are short on time, try doing interval training. If you have more time, do steady state cardio training. If you can, alternate the days to give variety and active rest in the workouts.

But you might ask, "What type of exercise is best for weight loss?"

Again, the answer is a balance of each of them. Essentially, there are three general categories of exercises that you can do: cardiovascular, flexibility, and strength. Each will help you on your way to weight loss. Here's how:

  • Cardiovascular: Cardio exercise is an obvious choice for weight loss. It gets you moving, it gets your heart rate up, and it burns calories as you are doing it. This is the first choice for those who wish to lose weight.
  • Flexibility: Flexibility will not burn a lot of calories, but it what it will do is help free up restrictions. As mentioned earlier, restrictions will limit your potential and can possibly even turn into an injury. You won’t be able to work as hard or burn as many calories with restrictions, so flexibility training will definitely contribute to weight loss.
  • Strength: When it comes to weight loss programs, people are hesitant to do strength training because muscle will add weight. But, in any weight loss program you should have more variables to measure than just weight. Body fat percentage, circumference measures, and even the fit of clothing should be good markers to monitor. The benefit of added muscle is unsurpassed by any other aspect of fitness. Muscle is a very metabolically active tissue. This means that just by having muscle, your body will burn calories to maintain and grow that muscle. This causes an increase in your resting metabolic rate (RMR). RMR is how many calories that you burn while ate rest. RMR can be 50-80% of your daily calorie burn. If you increase muscle mass, you increase the amount of calories you burn at rest on a daily basis.

Have a question? Ask an expert.

Also in this series:
Breaking Through the Plateau, 1
Breaking Through the Plateau, 2