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Exercise Intensity: How Hard Should I Exercise to Lose Weight?


Updated June 13, 2014

Girl Exercising

Work hard, but not every day

Henrik Sorensen/Taxi/Getty Images

Are you confused about how hard you have to exercise to lose weight? The truth is that low intensity aerobic exercise, moderate intensity aerobic exercise and high aerobic intensity exercise all play an important role in a well-designed weight loss program. What matters most is how you combine all three to create effective workouts.

If you are going to put in the time to exercise, make sure you enjoy the rewards. Learn the benefits of each exercise intensity and then learn to combine them to build an effective workout program that is safe, enjoyable and effective.

What is Low Intensity Exercise?

Some of your daily physical activity could be categorized as low intensity exercise. If you take your dog for a walk, go for a bike ride with the kids, or stroll to the grocery store to pick up dinner these things might be considered low intensity exercise.

Low intensity exercise increases your heart rate but not to the point that you have to breath heavily. On a scale of 1-10, low intensity exercise would rank between 4-6. Your heart rate during this type of activity would fall between 40-60% of your maximum heart rate. You should feel comfortable enough that you can continue the activity for a long period of time.

Benefits of low intensity exercise. The value of this kind of low-key activity is that you can do a lot of it. Low intensity workouts improve range of motion in your joints, lower your stress level, increase your total daily calorie expenditure and provide recovery from harder workouts that you may have scheduled during the week.

What is Moderate Intensity Exercise?

Experts often recommend moderate exercise for improved health and weight loss. But what does that really mean? Moderate intensity might be one workload for a fit person and something totally different for someone who is new to exercise. How do you know if your workout falls into the moderate category?

When you are participating in moderate intensity exercise, you should feel like you are working, but not working so hard that you need to quit in the next few minutes. You are breathing deeply but not gasping for breath. On a perceived exertion scale of 1-10, you should feel like you are working at a level of 6-7.

So how much moderate intensity activity is necessary? The American College of Sports Medicine offers guidelines for the amount of moderate intensity activity required to meet specific goals.

  • To see modest weight loss, exercise at a moderate intensity between 150 and 250 minutes per week.
  • To see clinically significant weight loss, you need to participate in moderate exercise for more than 250 minutes per week.
  • If you are combining diet and exercise to lose weight, engage in moderate intensity exercise between 150 and 250 minutes per week.
  • To prevent weight gain after you've lost weight, engage in at least 250 minutes per week.

Benefits of Moderate Intensity Exercise. The benefit of moderate activity is that it allows you to maintain your calorie burning session for a longer period of time. Moderate exercise improves cardiorespiratory endurance, reduces stress, improves heart health and boosts your metabolism. Because the intensity level of a moderate workout is tolerable, you are able to do more of these workouts during the week without risking injury or burn out.

What is High Intensity Exercise?

The most effective fat burning workouts are the sessions that you can only maintain for a short period of time. Because the work is so hard, high intensity exercise requires substantial recovery, both within the exercise session and in the days following the workout.

When you participate in high intensity exercise you are breathing very deeply and on the verge of gasping for breath. You don't feel that you can maintain the activity for more than a few minutes. On a perceived exertion scale, you feel like you are working at a level of 8-9.

Because high intensity exercises can only be maintained for a short period of time, they are often programed into interval style workouts. A popular form of interval training is called High Intensity Interval Training, or HIIT. To program a HIIT workout, you combine bursts of intense exercise that last 30 seconds to several minutes with short recovery periods that last 30 seconds or more.

Benefits of High Intensity Exercise. If you exercise to lose weight, high intensity workouts will do the trick. Experts have found that people who participate in high intensity interval workouts are more successful at losing weight and burning fat. High intensity exercise is also the most efficient. An intense workout will burn mega calories in a very short amount of time.

But there are drawbacks to high intensity exercise. Only healthy exercisers should participate in HIIT workouts. These extreme sessions put you at higher risk for injury and burnout. High intensity exercise also requires low intensity recovery time in the days following the session. This is where careful exercise programming comes into play.

Combine High, Low and Moderate Intensity Exercise to Lose Weight

If you are healthy enough for physical activity at every intensity level, plan 1-2 high intensity workouts during the week. These short workouts will help you burn maximum calories in minimum time. You'll also build muscle and boost your metabolism during these sessions.

On the days following your hard workouts, give your body a rest by participating in low intensity exercise. The increased range of motion during these easy days will help your sore muscles recover more quickly and you will still increase your calorie burn for the day without taxing your body too much and risking burn out or injury.

Fill in the rest of your workout week with moderate intensity sessions. Challenge yourself by making these sessions longer. The calorie burning benefits from these moderate workouts come from the duration of the session, no necessarily from the intensity.

Lastly, remember that if you exercise to lose weight, you need to watch your diet as well. Make sure you eat the right amount of lean protein, complex carbohydrates, fruits, vegetables and healthy fat to fuel your workouts. Count calories, measure your exercise intensity and record the data in a weight loss journal to track your progress.


Stephen H. Boutcher. "High-Intensity Intermittent Exercise and Fat Loss." Journal of Obesity October 2010.

Carey, DG. " Quantifying Differences in the "Fat Burning" Zone and the Aerobic Zone: Implications For Training." Journal of Strength & Conditioning Research: October 2009.

Donnelly JE, Blair SN, Jakicic JM, Manore MM, Rankin JW, Smith BK; American College of Sports Medicine. "American College of Sports Medicine Position Stand. Appropriate physical activity intervention strategies for weight loss and prevention of weight regain for adults. July 2009.

Eric Doucet, Neil King, James A. Levine, and Robert Ross. "Update on Exercise and Weight Control." Journal of Obesity October 2011.

EG Trapp, DJ Chisholm, J Freund and SH Boutcher. " The effects of high-intensity intermittent exercise training on fat loss and fasting insulin levels of young women" International Journal of Obesity April 2008.

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