J-Rod may be the fittest couple on the planet (apologies to Julianne Hough and Brooks Laich). The singer/dancer/actress and the former MLB star are constantly in the gym to shape their toned bodies or tackling 10-day diet challenges, and now they’re trying out a new weight loss method — fasted cardio.
Alex Rodriguez shared on Instagram that he and Jennifer Lopez were trying it out.
“Another beautiful day in New York City, about to go do a little fasted cardio,” he said, as Lopez jogged alongside him. “That means cardio before breakfast. This is from our trainer, Dodd [Romero]. Have a great day everybody!”
The idea behind fasted cardio is that working out without eating breakfast (and after the unintentional fasting that happens while you sleep) will burn the reserved fat in the body, rather than any food consumed ahead of time. It’s similar to the idea behind intermittent fasting, where people abstain from eating for around 14 hours a day to burn fat.
But researchers are conflicted over whether fasted cardio is actually effective. A 2013 study found that fasting every other day led to increased weight loss, as did a 2016 study that determined that doing cardio in a “fasted state” led to 20 percent more fat burning.
On the other side, though, a 2017 review of five studies found that any changes in body mass from fasted exercise was “trivial,” and several studies have warned that skipping breakfast in general is bad for overall health and leads to more weight gain.
The effectiveness also depends on the person, Dr. Douglas Paddon-Jones, a muscle physiology researcher and a professor of aging and health at the University of Texas Medical Branch, previously told TIME.
“You see some people advocating for fasted exercise on blogs and lifestyle sites, but these people tend to be young and in amazing physical shape,” he said. “Every other part of their diet and lifestyle is dialed in, they have no health issues, and when they eat, what they’re eating is super-high quality and carefully regulated.”
It may not work as well for the “average Joe,” Paddon-Jones said. But it is possible that it works for athletes like Lopez and Rodriguez.
The newly engaged couple recently upped their workouts as Lopez preps for her role as a stripper in the upcoming movie Hustlers.
Along with their frequent trips to the gym, Lopez said that she now has a portable pole in her house to practice her moves.
“It’s very hard!” she told Jimmy Kimmel in February. “I have bruises everywhere. It’s so hard. I have a lot of respect for people who do the pole. It’s much more difficult than [professional dancing]. It’s, like, acrobatic. It’s different muscle groups and the things they do with their legs, upside down, I’m like, ‘What? I can’t… hold on. Can we do that part again?’ It’s hard!”
The couple also embarked on a second round of their 10-day no sugar, no carb eating challenge, another suggestion from Romero.
“He said, ‘You know what, let’s do something, let’s take it [up a notch],’ ” Lopez recalled on Ellen with Ellen DeGeneres. “Because I’ve been working out, I work out a lot, I try to stay healthy. And he’s like, ‘Let’s do something to move the needle a little bit.’ “
Lopez said that she struggled with withdrawal symptoms from the lack of sugar when they first started the diet, but she soon adjusted.
“What happens is, it takes down the inflammation a little bit,” she said. “So all of a sudden you start feeling really small, and less swollen, and it feels good. You get addicted to that feeling too.”