What’s Better for Weight Loss—a Short HIIT Workout or a Long Walk? Health and Fitness Experts Weigh In

It is no secret that regular exercise is one of the most important health habits for losing weight. However, some workouts tend to be more effective than others when it comes to burning calories and blasting fat, according to experts. High-intensity interval training (HIIT) and walking are two of the most popular exercise methods for weight loss. Some people swear by quick but intense HIIT sessions, while others prefer to take long walks.

Which is more effective for weight loss? We asked a top trainer and obesity doctor to weigh in about the benefits of both, along with the answer we've all been waiting for.

Why Are HIIT Workouts Effective for Weight Loss?

Jillian Michaels, health and fitness expert and creator of The Fitness App, explains that it’s crucial to understand the mechanism of losing weight. “The primary method for weight loss is burning more calories than we eat in a day,” she says. “The reason this is crucial to comprehend is that one of the key mechanisms by which HIIT accelerates weight loss is via an elevated calorie burn.”

According to Michaels, HIIT is a great workout for almost anyone. “What might feel like high intensity for me could be a walk in the park for Jimmy Butler. So, keep that in mind and don’t be intimidated,” she says. The key is to challenge the individual at 85% to 100% of their maximum heart rate, which refers to the maximum number of times you want your heart to beat in a minute while exercising. “You can figure this out by simply subtracting your age from 220,” she specifies. For example, a 40-year-old woman would subtract 40 from 220 equaling 180. “So, in a HIIT workout, she would push herself until her heart rate is 85% to 100% of 180 beats a minute.”

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The reason why HIIT workouts are so effective for weight loss is that your body not only burns calories during the workout, but long after it's over. “Exercising intensely requires energy to perform so calories get burned while you do it,” Michaels says.

However, in a workout like HIIT, the “afterburn” effect on our metabolic rate is also elevated more than steady state cardio workouts. “This is called EPOC, which stands for Excess Post-Exercise Oxygen Consumption,” she continues. “It’s a fancy way of saying that after exercise, your body has an increase in oxygen consumption and resting metabolic rate because the body is recovering, repairing and working to return itself to its ‘pre-exercise state.’”

Because HIIT puts a maximal demand on the body, it requires more energy to perform and more energy to recover from, “so it burns more calories,” Michaels says. And as she explained, calories in versus calories out simply are “the bread and butter” of weight loss.

It also impacts several of the primary hormones that impact physiology. “It can elevate our HGH (human growth hormone) levels which helps with fat metabolism, muscle maintenance and insulin sensitivity. It boosts testosterone, which also works to promote fat metabolism, bone density and muscle growth,” she adds.

Plus, HIIT conditions the body’s core quickly “because your body is forced to adapt to the stress put upon it during your workout, AKA a stress adaptation response,” she continues. “The fitter you get, the faster you can run, the more you can lift, etc. HIIT improves cardiovascular conditioning—lung capacity, blood flow, etc.—which all burn more calories.”

HIIT also helps to regulate cortisol levels. “Contrary to popular belief, cortisol is a crucial hormone which facilitates a host of necessary bodily functions,” Michaels says. “We want cortisol elevated during exercise because it works in conjunction with HGH and catecholamines (dopamine, epinephrine and norepinephrine) also released during exercise to aid in fat metabolism.”

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What is the average length of a HIIT session? It can be anywhere from 20 to 60 minutes. However, unlike some other workouts, like walking, longer isn’t necessarily better.

“You might think that if HIIT is so awesome why am I doing it for such a short period of time? Shouldn’t I do it for 45 minutes instead of 20 if the results are so awesome? The answer is simply, no,” explains Michaels. “This is because too much stress is counterintuitive and long bouts of HIIT create too much stress. Not only do you risk injury, but you can throw your cortisol levels out of whack if you train too hard, too often, without adequate recovery. And we all know that chronically evaluated cortisol levels are not ideal—especially for weight loss.”

Why Is Walking Effective for Weight Loss?

David Creel, Ph.D., RD, a psychologist and registered dietitian in the Bariatric & Metabolic Institute at Cleveland Clinic, explains that a few factors determine how many calories can be burned in a walk: how much a person weighs, the speed of the walk and how far the person goes.

“The more a person weighs, the more calories that are burned at a given speed,” he explains. However, there are other ways that walking can indirectly aid in weight loss. For example, exercise can help boost mood, improve sleep and offer someone a sense of mastery. “These effects may indirectly impact weight loss by changes in eating habits,” Creel points out. “If someone is an emotional eater and they manage stress better as a result of exercise, they may lose weight.”

And, because poor sleep is associated with a negative impact on hunger hormones, if exercise improves sleep, it may help with diet. “Some people exercise and it motivates them to eat better,” he explains.

Michaels adds that walking also helps lower blood pressure, support cardiovascular health, can help lower cholesterol, ease joint pain, boost the function of our immune system and so much more. “It also improves insulin sensitivity, which supports better metabolic function,” she says.

Which Is More Effective for Weight Loss: A Short HIIT Workout or a Long Walk?

Because of the afterburn effect explained by Michaels, for most people, doing a short but intense HIIT session will be more effective for weight loss than a long walk. However, some people might find that walking results in more weight loss success. Dr. Creel points out that for some individuals, HIIT increases the risk of burnout or injuries—making them less likely to actually do it.

“The best exercise tends to be the one you’ll do on a regular basis,” he says. If you want to start doing HIIT workouts, he suggests focusing on frequent lower-intensity exercise until forming a habit. Then, increase the intensity once your fitness improves and you feel the urge to challenge yourself with higher-intensity workouts. He also notes that people who are inactive and have conditions such as heart disease or diabetes should check with their doctor before starting HIIT training.

“Long-term, I recommend people do various types of exercise (cross-training). Alternating between more intense shorter workouts and longer, lower intensity training is a nice way to prevent boredom and maximize fitness,” he says.

While short HIIT sessions are more effective for weight loss than long walks, Michaels suggests a combination of both. “I try to get 5,000 to 10,000 steps in every day,” she says.

Next up: Here's How Much Cardio You Actually Need To Do Every Week To Lose Weight