That ad says cardio won’t help me lose weight—is that right?

By Madeline Keleher

Mar 3, 2021

You may have heard that high-intensity interval training (HIIT) is superior to a regular cardio workout. You’ve certainly heard this if you’ve seen any V Shred ads featuring fitness model Vince “Shirts Are Unnecessary” Sant. He claims that a regular cardio workout like jogging or pedaling an exercise bike increases your body’s production of the stress hormone cortisol longer than any other type of workout. According to Vince “Absolutely Absorbed With My Own Abs” Sant, this stresses out your body and leads to body fat retention. Instead, Vince wants you to HIIT up V Shred. Is that right?

First, what is V Shred and should you believe them? V Shred is an online fitness company founded in 2015 by Vince and three other white guys. They sell difficult-to-cancel subscriptions, smartphone programs for “xtreme” fat loss (for him and for her), and caffeine capsules with cayenne extract that allegedly “burn fat” but come flagged with the obligatory fine print that they don’t treat any disease, that the FDA hasn’t evaluated them, and that in fact all content on their entire website isn’t medical advice. So, I don’t believe anything coming from V Shred or Vince “HIITs The Gym Not The Books” Sant. Neither do the commenters on the surprisingly delightful Reddit thread dedicated to Vince’s ads, which one user accurately notes is the first Google hit for the search “who is the douchebag that said he never does an hour of cardio ad.” The only part of the V Shred website I agree with is in the fine print: “consult your physician and follow all safety instructions before beginning any exercise program or using any supplement, nutrition plan, or meal replacement product.”

Does a regular cardio workout actually mess with your hormones? Not in a bad way. Cortisol levels raise in response to stress, and exercise is a stressor for your body. Both moderate and high intensity exercise increase cortisol in your blood after you work out. That is a normal, essential part of your body’s metabolic response to exercise. The cortisol levels come back down within hours. Don’t avoid exercise fearing it will raise your stress levels over time: regular exercise actually makes people more resistant to stress.

How is HIIT different from a regular cardio workout? It’s like taking course overloads and graduating college 4 semesters early. Or like eating breakfast, lunch, and dinner in one sitting and then fasting the rest of the day. Instead of working out at around 40-60% peak heart rate at a steady pace (for instance 45 minutes on an elliptical, treadmill, or Peloton), with HIIT you cram a workout into under 30 minutes by exerting yourself at maximum effort (80-95% peak heart rate) in bursts of 30 seconds to a few minutes, separated by a few minutes of low-intensity recovery exercise. Vince “My Abs Ripped Through My Shirt” Sant claims that high-intensity intervals longer than 30 seconds aren’t HIIT, but he’s wrong. There is no universally accepted interval length, recovery length, or peak heart rate for HIIT.

Out of thoroughness, I tried Vince’s 12-minute HIIT cardio workout, which has over 4 million YouTube views. I reached 82% of my peak heart rate and was able to keep my shirt on the entire time (unlike Vince, who tore his off halfway through). I did fine with the high knees and jump lunges, but the push-up side planks were brutal. I have what my sister calls “dainty wrists,” and my shaky fourth round of push-ups nearly became face plants. After completing the workout, I laid down for 5 minutes, mildly nauseated and regretting the pizza I’d had three hours earlier. The workout itself wasn’t that hard to endure because I got a break every 30 seconds, but for the next three days I was sore. Was this torture worth it? It’s time to check the science on Google Scholar.

Is HIIT better than regular cardio? Vince “Braun Over Brains” Sant is wrong when he says regular cardio doesn’t promote weight loss. Study after study has found that HIIT and regular cardio are equally as effective for weight loss for people with overweight or obesity.

In a study of 32 pre-diabetic men who did 12-weeks of HIIT, regular cardio, or no exercise, insulin resistance improved in both exercise groups (37% improvement with HIIT and 35% for regular cardio, with no significant difference between the two). Other studies have corroborated this finding that both types of exercise equally improve insulin sensitivity.

There is one area, however, where HIIT does seem to have regular cardio beat: improving cardiopulmonary function. A study of 22 men with chronic heart failure did 12 weeks of HIIT or regular cardio on a treadmill. Both types of exercise were equally as effective in improving quality of life and functional capacity—however, the HIIT group improved more on the cardiopulmonary exercise test (11% improvement compared to 8%). The superiority of HIIT over regular cardio for cardiopulmonary function has been corroborated by other studies, although some studies have found the improvement to be equal.

A meta-analysis of 22 studies comparing HIIT with regular cardio in adults with overweight and obesity concluded both forms of exercise significantly reduce weight and cholesterol, while HIIT regimens with an intensity interval of at least 2 minutes can significantly increase cardiopulmonary fitness (so Vince “I’m Not Overcompensating You’re Overcompensating” Sant may want to rethink setting his cap at 30 second intensity intervals). And you needn’t choose one over the other. Women with severe obesity who combined HIIT with regular cardio for 24 weeks lost 3 kg (6.6 lbs) more than women who just did regular cardio. However, a study of 379 inactive adults who were assigned to HIIT or regular cardio for 6 months found that those in the HIIT group didn’t stick with the regimen as well and overall they exercised less. A study of 250 adults had a similar outcome: these participants were allowed to choose if they wanted to do HIIT or regular cardio, and of those who chose HIIT, only 60% completed the workouts twice a week in the beginning, and after a year merely 20% did. People who find HIIT unpleasant don’t keep it up.

The bottom line is, choose whatever exercise regimen works for you and run it by your doctor. Vince has his knee crunching lunges and his perpetually exposed sweaty abs, and I’m happy for him. I prefer a leisurely jog around the park while listening to a podcast, followed by pedaling my stationary bike while reading the news. To each their own. Just make sure every week you fit in at least 75 minutes of vigorous-intensity activity (like running or swimming laps) or 2.5 hours of moderate-intensity activity such as brisk walking, gardening, or water aerobics. This will reduce your risk of death by 33%. If you’re trying to lose more than 5% of your body weight or keep weight off after having lost it, shoot for at least 5 hours of moderate-intensity activity per week.

Happy exercising!

Figure from the American Heart Association.