Victoria's Secret models have some of the most envied figures in the world.
And while they're clearly blessed with good genes, they also work hard to look so stunning on the catwalk.
You'd expect this involves a punishing regime of intense military-style exercises that most of mere mortals couldn't hack for long.
But this isn't so, according to celebrity trainer Michael Blauner, who has helped many of the famous beauties to stay in shape.
He says he has them doing low-intensity sustained state (LISS) cardio and what's more, the New Jersey fitness expert says this produces the best fat-burning capacity in your body.
"Theoretically, long-duration lower-intensity cardio has been considered the best type of cardio workout for weight loss," he told Popsugar.
"You tap into stored fat more when the body uses oxygen as an energy source."
It's contrary to what other experts say: That high intensity training (HIIT) torches maximum calories in a minimum amount of time.
MIXING IT UP
HIIT has had the fitness industry buzzing. The idea is that you do short periods of all-out work followed by short periods of active rest to make the body work harder than it does during steady-state cardio.
But LISS involves doing light cardio - 50 to 60 per cent of your maximum heart rate - at a consistent pace, usually for long durations.
This type of workout lasts a bit longer than your typical interval session, at around 30 to 60 minutes.
LISS training is any low endurance workout such as walking, swimming, or cycling, but all at a relaxed level. A hike is perfect as you're generally not pushing your body to extremes.
But Michael isn't suggesting people only do LISS, but says it's the cardio he suggests to clients over everything else.
"I like to mix in very fast paced, short blasts of higher intensity cardio that develops your cardio system to a higher level,' Michael said. 'This way you get the best of both worlds."
That also keeps you from feeling bored during these longer sessions of cardio.
Therefore, it might be a good idea to mix some LISS sessions into your fitness routine, especially if you're the kind of person who sticks to HIIT on the regular.
HIIT WORKOUTS ARE NOT SUSTAINABLE SAYS PROFESSOR
High intensity interval training (HIIT) has become a popular way of getting fit because of its calorie-torching reputation.
It has also been linked to body fat mass reduction and touted as a way to combat high insulin resistance, which causes diabetes.
But now a professor has wanted the workouts are not sustainable for the majority of people trying to lose weight and increase their activity levels.
Dr Panteleimon Ekkekakis, a professor of kinesiology at Iowa State University, studies how our bodies and brains respond to exercise.
He says the entire premise of HIIT - which involves alternating between intense bursts of exercise and fixed periods of less-intense activity - guarantees a level of displeasure and therefore does not encourage people to stick to it.
"If you can take an hour of exercise and squeeze it into one minute, there's a price to pay,' he said.
"The price is 100 per cent intensity. It's undeniable that the experience will be unpleasant."