Have you ever seen the term MET on a piece of exercise equipment and wondered what it meant? MET stands for metabolic equivalent, which is one way that exercise physiologists estimate how many calories are burned during physical activity. Having a basic understanding of METs and how to use them can help you determine the best physical activities to help your health and fitness goals.

WHAT EXACTLY IS A MET?

Muscle cells use oxygen to help produce the energy to fuel contractions; the more oxygen you consume during (and after) exercise, the more calories you will burn. The human body expends approximately 5 calories of energy to consume 1 litre of oxygen. The more oxygen your body uses during physical activity, the more calories you will burn.

METs are used to estimate the energy expenditure for many common physical activities. One MET is an individual’s resting metabolic rate (RMR) and is approximately 3.5 millilitres of oxygen consumed per kilogram bodyweight per minute (mL/kg/min) and represents the amount of oxygen used by the body while at rest (such as what you’re doing right now while reading this article). An activity that is 4 METs requires the body to use approximately four times as much oxygen than when at rest, which means it requires more energy and burns more calories.

If your fitness goals include weight loss, understanding which physical activities help burn the most calories can help you determine the most effective activities they should be doing to meet those goals. Here are five things to understand about METs and how to use them.

1. The Compendium of Physical Activityidentifies MET values for a wide variety of physical activities.

Researchers have assigned MET values for everything from many common types of exercise to relatively obscure activities like pulling a rickshaw. For example, walking at a moderate pace of 2.8-3.2 miles per hour (mph) on a level, firm surface is approximately 3.5 METs, which means that the body is using 3.5 times the amount of oxygen than is required when sitting still at rest. Running at 7.0 mph, which allows you to cover one mile in approximately 8.5 minutes, has a MET value of 11.0 (meaning your body uses approximately three times the amount of oxygen used while walking and 11 times more oxygen than sitting at rest). By the way, pulling a rickshaw is 6.3 METs.

2. If you know the MET value of a physical activity, the duration of that activity and a little about the person participating in the activity, you can estimate how many calories a minute that individual should burn doing that activity.

Pick a favourite physical activity or mode of exercise and plug the MET value into the formula below to see how many calories you burn per minute and whether or not you should increase the level of intensity or duration to help achieve a specific goal like weight loss:

• METs x 3.5 x BW (kg) / 200 = Kcal/min.
• For example, Shane is a 40-year old male who weighs 195 pounds. You can use this formula to determine how many calories per minute he uses during some of his regular activities:
  • 2 hours of bicycling @ 12.0 mph (METs: 8.0)
  • 0 x 3.5 x 88.6 / 200 = 12.4 Kcal/min x 120 = 1488 Kcal
  • 45 minutes of resistance training – explosive effort  (METs: 5.0)
  • 0 x 3.5 x 88.6 / 200 = 7.8 Kcal/min x 45 = 351 Kcal

3. One pound of fat contains approximately 3,500 calories of energy.

Using the formula, you can determine how long it would be necessary to perform a given activity to burn the equivalent of 1 pound of fat. For example, using the example above, Shane would have to ride his bike at 12 mph, which burns 12.4 calories per minute, for 283 minutes to burn one pound of fat. If his goal is to lose 10 pounds of body fat, he will have to cycle for 2,830 minutes or 47 hours, which is more than the equivalent of a full week of work.

4. Sit or stand? Many organizations are starting to realize the health benefits of providing employees with standing desks.

Using the MET values for sitting and standing, we can see that Shane can burn almost 30 percent MORE calories by simply standing instead of sitting for one hour. Taking it a step further, we can see that it will take Shane about 1,250 minutes (approximately 21 hours) of standing to burn 1 pound of fat.

• Standing at work for 40 min. compared to sitting at work for 60 min.
  • 8 x 3.5 x 88.6 / 200 = 2.8 Kcal/min x 60 = 168 Kcal
  • 3 x 3.5 x 88.6 / 200 = 2 Kcal/min x 60 = 120 Kcal
  • 1 pound of fat – 3,500 calories / 2.8 Kcal/min = 1,250 minutes

5. If you want to help you to maximize your energy expenditure, look at your activities of daily living to see which ones burn the most calories.

MET values can provide a broad estimate for how many calories are being used, but it isn’t exact. However, they still can be helpful in planning more efficient workouts and estimating how many calories are being used during a wide range of activities, including yard work, running errands or hitting the gym for your favourite workout.