During a recent discussion with a number of clients the subject of exercise and weight loss came up. There is a lot of misconception about what types of exercise promote fat loss, the largest one being that it takes long hours on the treadmill (or doing any aerobic exercise) in order to lose weight. Luckily, research has shown this not to be true.
Rev it up to burn more body fat
The short version of this discussion breaks down to this: exercising at a higher intensity (like burst or interval training) provides two benefits over workouts at a lower heart rate: (1) an after burn effect and (2) more calories burned during the workout.
The reason the after-burn exists is that certain forms of exercise throw your body into a short-term bout of chaos causing it to expend energy in the form of calories to fully recover to a balanced state. This process can take between 15 minutes and 48 hours depending on the type of exercise and the amount of time spent exercising. The most important factors that determine the magnitude of the after-burn effect are the intensity and duration of exercise. Basically, the longer and harder you work out, the more calories you will burn once you finish exercising.
The other main benefit of working out at higher intensities is that you burn more calories in a given amount of time. While it is true that you can burn proportionately more calories from fat by working out at lower intensities (when you’re in the fat burning zone), you burn more total calories and more total fat calories by ramping up the intensity. The chart below details the calorie expenditure by a 130-pound woman during two exercise sessions (MHR = maximum heart rate):
|
|
Low Intensity: 60-65% MHR |
High Intensity: 80-85% MHR |
| Total calories burned per minute |
4.86 |
6.86 |
| Fat calories burned per minute |
2.43 |
2.70 |
| Total calories burned in 30 minutes |
146 |
206 |
| Total fat calories burned in 30 minutes |
73 |
82 |
| Percentage of fat calories burned |
50% |
40% |
Looking at this chart, you can see that working out at lower intensity burns 50% of the calories from fat, or 73 total calories. However, more fat calories are burned (82) and more total calories (206 versus 146) are burned at the higher intensity even though the percentage of calories burned from fat is less (40% vs. 50%). So even though it is technically correct that you burn a higher percentage of fat calories at lower intensities, you will burn more fat calories and more total calories which means greater weight loss, with high intensity workouts.
And don’t forget that working out at higher intensity also provides a greater after-burn effect, causing the overall calorie burn from high-intensity workouts to be much greater than low-intensity workouts. This means that if time is tight, focusing on high-intensity workouts will help you reach your weight-loss goals faster.