High-Intensity vs. Low-Intensity Workouts

Jul 10, 2014

By Ben Hwa, BLITZ Program Director

For many people, losing fat is a big part of their fitness plan. Here’s what you need to know about burning fat using high- and low-intensity workouts.


With the rise of P90X and CrossFit, you may have heard the term “high intensity.” Although high-intensity workouts offer huge benefits, there are also advantages to performing low-intensity exercise. For example, traditional cardiovascular workouts such as running or swimming.

Low-intensity exercises include any type of training long in duration and submaximal in effort. When you workout this way, calories are initially burned from glucose and then from fat storage. Low-intensity training also develops an increase in mitochondrial density in your muscles, which helps you burn fat more efficiently. These cells operate as “tiny fat-burning factories.” The more you have the better. The one downside to this type of training is the potential muscle loss. Although this seems like the best way to burn fat, it definitely isn't the only way.

High-intensity workouts are just as beneficial for fat loss, if not more beneficial than low-intensity. Examples of these anaerobic workouts include interval-based training or high-intensity circuits. The caloric expenditure for this type of training is more per minute than low intensity. And although a majority of this calorie spending is from carbohydrates, more fat is usually burned due to the difference in total calories lost.  There’s also an additional benefit to high-intensity training during a phenomenon called excess post-exercise oxygen consumption (EPOC). Often called the “after-burn,” it refers to the body spending energy hours after a workout – the higher the workout intensity, the more EPOC involvement. 

While high-intensity training might seem to burn more fat on a weekly basis, it’s also a more difficult exercise regimen to maintain. It’s easy to over-train at high intensity every day. The best way to avoid this is to alternate between high- and low-intensity workouts during the week.

Both of these types of training encourage fat loss. The important thing to realize is there isn't just one way to accomplish this goal.