Meaning of Metabolic Equivalent

What is metabolic equivalent?

Metabolic equivalent is an abbreviation for the English term 'metabolic equivalent', read as MET or 'met'. It is a unit used to compare the energy expenditure of a specific activity to that of a resting state. It is convenient for classifying different activities, such as walking, running, or housework, on the same scale.

Based on 1 MET, a 4 MET activity means the intensity uses approximately four times more energy than at rest. This does not mean that an individual's body fat is reduced four times faster.

How is 1 MET determined?

Traditionally, 1 MET is considered the resting expenditure corresponding to an oxygen uptake of approximately 3.5mL/kg/min or approximately 1kcal/kg/hour. This is a conventional standard for calculation and classification; the actual resting metabolic rate of every person is not exactly this value.

An individual's resting metabolism can vary depending on age, gender, body composition, and medical conditions. Especially in elderly or obese individuals, the standard 1 MET may overestimate or underestimate the actual resting state.

Where do the MET values for activities come from?

Activity lists provide representative values by collecting data on oxygen and energy consumption measured in research. Materials that organize codes by activity type, speed, and intensity, such as the 2024 Adult Physical Activity Summary, are used in research and public health.

Even for the same 'walking', values differ depending on speed, incline, weight of luggage, and terrain. A single number is not applied to all situations based solely on the name of the activity.

How are low, moderate, and high intensities categorized?

In adults, it is common to categorize less than 1.5 MET as Sedentary behavior, 1.5~2.9 MET is classified as light intensity, 3.0~5.9 MET as moderate intensity, and 6.0 MET or more as vigorous intensity. These thresholds are used to describe the absolute energy demands of activities.

For someone with low physical fitness, 4 METs may be very strenuous, while for a trained individual, it may be light. It is important to distinguish between absolute intensity and an individual's relative intensity.

What are some examples of moderate-intensity activities?

Brisk walking, cycling at a moderate pace on flat ground, and some household chores or gardening may fall within the moderate-intensity range. However, the value varies depending on the actual speed and how the activity is performed. Moderate-intensity activitycan be identified by breathing and speaking levels rather than just the name of the activity.

Generally, being able to talk but finding it difficult to sing is a practical clue for moderate intensity. This is particularly useful when heart rate responses vary due to medication or medical conditions.

Is high-intensity activity the same for everyone?

Running, fast swimming, and high-intensity cycling are generally 6 METs or more. However, for an untrained person, an activity with a low absolute MET value can be relatively high intensity. If you are very short of breath and can only speak in short sentences, the intensity felt by the body is high.

If you are starting exercise for the first time or have cardiovascular, respiratory, or joint problems, do not set a high MET number as your initial goal. Gradually increase from low intensity and short durations.

How are MET-minutes calculated?

MET-minutes are calculated by multiplying the activity's MET value by the duration in minutes. For example, performing a 4 MET activity for 30 minutes equals 120 MET-minutes. This is used to sum the weekly volume of various activities into a single unit.

Even for the same 120 MET-minutes, 30 minutes at 4 METs and 15 minutes at 8 METs differ in perceived exertion, preparation, and recovery. Having the same total does not mean the training effect and safety are exactly the same.

How does this connect to exercise guidelines?

Adult physical activity guidelines generally recommend an amount equivalent to 150~300 minutes of moderate-intensity aerobic activity or 75~150 minutes of vigorous-intensity activity per week, along with muscle-strengthening activities on 2 or more days per week. MET-minutes can serve as a research and counseling tool for combining moderate- and vigorous-intensity activities.

Rather than trying to meet the minimum criteria all at once, spread it throughout the week to fit your lifestyle. If you currently have almost no activity, simply starting with a small amount is meaningful.

How are calories estimated?

A simple formula approximates kcal as 'MET × body weight (kg) × time (h)'. For example, if a person weighing 70kg performs a 4 MET activity for 0.5 hours, it is calculated as approximately 140kcal. However, since this formula uses a standard 1 MET and representative values for activities, it is not an exact measurement of actual expenditure.

Efficiency, body composition, wind, incline, and device errors can change the results. Do not use calculated exercise calories to directly compensate with food intake or convert them into weight loss amounts.

Why is it different from smartwatch values?

Wearables use movement, heart rateand user information in their own algorithms to estimate calories and intensity. MET tables use representative values for activity groups. Because the inputs and algorithms differ, a discrepancy between the two values does not necessarily mean one of them is malfunctioning.

Use device numbers to observe repeated patterns with the same device, rather than relying on decimal-point accuracy. Errors also vary depending on wrist placement, skin contact, and the type of exercise.

How is it different from heart rate zones?

Heart rate zonesuses estimated maximum heart rate or heart rate reserve to look at an individual's relative intensity. METs are closer to the absolute intensity required by the activity itself. Beta-blockers, heat,dehydrationand stress can change the heart rate response.

Using METs, heart rate, and the talk test together can compensate for the limitations of a single indicator. For patients with a prescribed exercise regimen, the criteria set by their medical provider take priority.

How is this used for weight loss?

By organizing a week's worth of walking, cycling, housework, and planned exercise into MET-minutes, you can see the overall trend of your activity level. Rather than only increasing high-intensity exercise, create a sustainable total volume by combining moderate-intensity activities, daily movement, and strength training.

If food intake increases due to overestimating exercise calories, weight changes may differ from expectations. Daily energy requirementsis also an estimate rather than an exact fixed value, so adjust your plan based on weight and waist trends over 2 to 4 weeks.

How to safely increase intensity

First, stabilize the frequency and duration, then gradually increase speed, incline, or resistance. Include warm-ups and recovery days, and modify movements that cause recurring pain. On days when heat, lack of sleep, and reduced food intake overlap, do not mechanically try to meet your usual MET goals.

If chest pain, fainting, abnormally severe shortness of breath, or throbbing occurs, stop exercising and seek a medical evaluation. diabetes Those taking medication also need a plan for hypoglycemia.

When individual consultation is necessary

If you have cardiovascular or pulmonary diseases, uncontrolled blood pressure, recent surgery or childbirth, joint pain, or are starting exercise after a long period of inactivity, please check your individual intensity levels and contraindications. The numbers in the MET table do not replace a medical evaluation.

While taking Baekrok Gambi-jeong, if you experience recurring dizziness, tremors, or severe throbbing after increasing exercise intensity along with reduced food intake, do not push yourself. Instead, inform the Baekrokdam medical staff about your exercise duration, symptoms, and medication status to adjust your plan.