Sherri McMillan: Burn fat, should you go hard or easy?



Spring is here, reminding everyone that shorts, dresses, skirts, tank tops and bathing suits and in the near future. That tends to be the kick in the butt than many need to start taking better care of themselves to lose fat and tone up.

But many people are still confused as to which intensity of exercise will burn the most amount of fat.

You may have heard in the past that lower intensity activity will maximize fat loss or “Go at an easy, slow pace for longer to burn fat”. The thought was that if you worked too hard, you’d just be burning sugars and not fat. So, many fit people lowered the intensity of their workouts fearful that they were not burning fat.

Unfortunately, they were misled and many people still believe that low intensity activity is the best way to maximize fat loss. The reality is that the activity that expends the most amount of total calories will lead to the most amount of fat burned.

Yes, during lower intensity activity you will burn a greater percentage of fat and during higher intensity activity you will burn a greater percentage of carbohydrates or sugars. But the important point to note is that the total amount of fat burned is a percentage of the total calories burned. So if you’re not burning a lot of calories, then you’re not burning a lot of fat. The selective use of fat as a fuel, specifically at lower intensities, does not translate into greater fat loss, regardless of how tempting it is to draw this conclusion. The most important focus with regard to fat loss is not the percentage of energy coming from fat, but rather the total volume of fat used and the total number of calories expended.

No fat sprinters

Consider this: If lower intensity exercise is really the best way to burn fat then why aren’t sprinters fat? The majority of their training is at a very high intensity effort but because they are burning so many calories they maintain a very strong, lean physique! Also consider that the highest percentage of fat you can physically burn is when you are resting and doing nothing. But at rest, of course, you aren’t burning a lot of calories so although you’re burning a higher percentage of fat, a higher percentage of nothing is still nothing!

The reality is that lower intensity exercise burns less calories and high intensity exercise burns more calories.

So if you’re going easy, you’re going to have to go longer. And if you’re going really hard, you can get away with a shorter workout.

Maximizing results

Time is definitely an issue for a lot of exercisers and most don’t want to spend hours in the gym if they can get the same results in a shorter period of time.

So, the bottom line is that if you want to maximize fat loss, you need to maximize the number of calories you expend. The American College of Sports Medicine suggests that a workout should expend 300 calories in order to be deemed a fat loss workout. This is equivalent to about 3 miles of jogging or power walking or 30 minutes of stepping.

A great approach to your cardiovascular training is to mix up your intensities. That is, sometimes you go easy and long and other times you go hard and fast. You might for example, do a 20 minute hard interval workout Monday, a moderate 40 minutes of cardio Wednesday and Friday, you might go for an hour walk.

Note: We are starting our Spring Makeover Challenge soon. It’s a fun and friendly competition to help inspire you to take the actions necessary to lose weight and get in great shape for summer. Sign up now before teams fill up!

Sherri McMillan, M.Sc. is the owner of Northwest Personal Training in downtown Vancouver. She can be reached at or