Buzz
If you’re the type who spends every Saturday in Lululemon leggings and has a Smartwater® bottle in hand, you’ve likely heard about Orangetheory Fitness. This Florida-based franchise, with its signature orange lighting and cutting-edge workout spaces, has become a fitness trend that’s rivaling Soulcycle. With over 700 locations, the company has more than doubled its size since the end of 2015. One of its biggest selling points is the claim that their workouts help you continue burning calories even after you've finished, showered, and gone home. Orangetheory’s website promotes this with the slogan, 'Work for 1 Hour. Burn for 36.'
Orangetheory’s trainers push participants to give it their all through a variety of workout stations, including treadmills, rowing machines, and weight rooms. Everyone in the class wears a heart rate monitor, with TV screens in the high-tech centers displaying each person's name and heart rate during the class. Participants earn points based on how many minutes they spend with their heart rate in the 84 to 100 percent range of their maximum heart rate during the 60-minute workout.
While there’s nothing inherently wrong with Orangetheory’s workouts, and if you enjoy the experience, they can be a great way to stay fit, it’s important to keep a few things in mind if you’re drawn to the program based on its calorie-burning claims.
Their 'Theory' is the EPOC Effect
The idea behind Orangetheory is that excess post-exercise oxygen consumption (EPOC), or 'afterburn,' helps burn more calories. This theory suggests that after intense, heart-raising workouts, the body continues to burn fat long after the exercise is completed to restore balance.
'It takes oxygen to burn that fuel,' explains Martin Gibala, professor and chair of the Department of Kinesiology at McMaster University in Ontario. 'There’s a direct connection between oxygen use and calorie burning.' Gibala has led experiments that measure the calorie burn associated with high-intensity exercise.
When you're gasping for air after a run, your body is collecting the necessary resources to keep the calorie-burning process going. In some cases, the body continues to burn calories for hours afterward. Scientists can track this effect by having subjects breathe into a tube to monitor how much extra oxygen they take in. More oxygen means that, although you seem to be resting, your body is still breaking down fat to recover from an intense workout, similar to something you’d see in a 'Rocky' montage.
But EPOC doesn’t lead to significant additional calorie burning.
While physiologists have been aware of the EPOC effect since the early 20th century, research hasn't shown that high-intensity interval training, the kind of exercise that triggers EPOC, provides a major weight-loss advantage over steady-state cardio.
"Personal trainers often emphasize 'afterburn,' but it’s typically exaggerated," says Gibala. (Orangetheory did not respond to a request for a science officer or consultant to discuss its claims.)
Male long-distance runners tested this theory in a study published in the Journal of Applied Physiology in 1997. Some ran continuously on a treadmill, while others alternated between sprinting at their maximum speed and taking breaks, triggering the EPOC effect. The runners with the more intense intervals did indeed consume more oxygen, but it wasn’t enough to significantly impact metabolism or weight loss. The study concluded: "The primary contributor to weight loss from running is the energy expended during the exercise itself."
A 2006 review of the available research by Australian physiologists found that "early optimism regarding EPOC's role in weight loss is generally unsupported." The researchers agreed that nearly all the calories burned during exercise are burned in the process itself, not during an afterburn effect.
So, what happens when you combine the calories burned during exercise with the afterburn effect? Gibala’s team at McMaster University conducted a 2014 study to assess the benefits of EPOC. Cyclists were put on controlled diets and activity routines before and after workouts. One group did a 20-minute high-intensity interval training session designed to keep their heart rates near 90 percent of their max, while the other group cycled moderately for 50 minutes. Within 24 hours, both groups consumed a similar amount of oxygen.
This doesn’t mean that the two groups burned the same number of calories per minute. Naturally, cycling at full intensity burns more calories than cycling at a slower pace. In the McMaster study, those who pedaled at near-maximum intensity burned 3,368 calories in 20 minutes, while those cycling at a moderate pace burned 3,464 calories in 50 minutes. This shows about double the number of calories burned per minute in the high-intensity group.
While it’s more time-efficient to engage in intense workouts for shorter durations, the calorie burn from 20 minutes of frantic exercise is about the same as a 50-minute aerobics class, and almost all of those calories are used during the exercise itself, not through EPOC. So, if 50 minutes of continuous exercise feels more manageable, the benefits are roughly the same.
It Might Be More Effective to Focus on Nutrition and Moderate Exercise
The intensity of exercise is one of the reasons EPOC doesn’t significantly benefit most gym-goers. "To see much of an effect, you need to be an athlete training daily or a fitness instructor," says Christopher B. Scott, a professor of exercise, health, and sport sciences at the University of Southern Maine, who has researched EPOC. "In simple terms, you need to train hard and long to experience the 'afterburn.' For most people, it's just wishful thinking."
Gibala also points out that in the discussion about exercise's calorie-burning potential, what often gets overlooked is that altering your diet tends to lead to better outcomes. "Diet is the main driver of weight loss," he says. "Modifying your diet can have a moderate impact on weight loss. Exercise is primarily beneficial for cardiovascular health."
