RFK Jr.'s Weird Jeans Workout Habit Has A Hidden Side Effect That's Actually Pretty Gross

Based on photos, Robert F. Kennedy, Jr., has a toned and fit physique. Some attribute it to his devotion to the Make America Healthy Again diet. However, he seems to overlook the standard workout attire that you'd find in most Planet Fitness or Crunch facilities. Specifically, Kennedy gets active while wearing denim — yep, jeans. And there's lots of social proof (on platforms such as X, Instagram, and YouTube) of him doing hardcore exercises in this garb, which is not exactly the healthiest practice.

I teamed up with @SecDef Hegseth for the "Pete & Bobby Challenge" — 50 pull-ups, 100 push-ups. This is the start of a nationwide push to get Americans fit again. We're calling on our friend @SecDuffy to take the challenge. pic.twitter.com/TTlv9VvkCe

— Secretary Kennedy (@SecKennedy) August 19, 2025

Kennedy's unusual and potentially gross workout habit has garnered plenty of attention from people who all have the same question: "But why?" Apparently, Kennedy adopted his jeans-are-for-the-gym habit out of convenience (via Fox News). Instead of having to change into different clothes after his morning hike, he just stayed in his jeans. And he's hardly alone: It seems like jeans pop up at gyms more than you might realize, as some fitness enthusiasts appreciate the way that jeans make them look and feel when they're exercising.

This leads to a second question: Is it a good idea to do cardio, lift weights, etc., in denim? As it turns out, unsurprisingly, it's not a practice that most experts would recommend.

Traditional denim may be versatile, functional, and comfortable, but it's generally not the most breathable fabric. When you sweat in a pair of jeans, the sweat soaks into your pants, which in turn results in a breeding ground for germs. According to dermatologist Dr. Alok Vij (via Cleveland Clinic), bacteria buildup on jeans can cause folliculitis (which looks like acne) on your legs and bottom. (Fortunately, you can get rid of folliculitis with different treatments.)

Yet folliculitis isn't the worst that can happen. Dr. Vij said that if you have a fungal condition like athlete's foot, the fungus could transfer to your jeans as you pull them on. He added, "If you wear those jeans again and again without running them through the wash, you may pass the fungus to your groin or thigh. Now, you don't just have foot fungus — you've got jock itch, too." (Another way to prevent crotch itch is by avoiding underwear mistakes like sitting around in sweaty panties and briefs.)  Also, as university professor Dr. Kelly Reynolds explained to Self, bacterial growth in gym clothing can cause it to stink.

Some experts might disagree, though. Canadian professor Rachel McQueen told Business Insider that in an effort to promote scientific research, a student of hers wore his jeans for 15 months without washing them. Surprisingly, the "bacterial load" on the jeans was about the same as when he'd worn them for just 13 days.

Does this mean that Kennedy might be on the cusp of a new workout trend, after all? Probably not, if you're at all into smelling nice or avoiding preventable dermatological conditions. Medical director Dr. Jeremy Fenton cautioned that putting bacteria-laden clothing near your body (especially your genitals) could lead to a yeast infection.

Back to Kennedy: While it seems that he's probably not in danger of experiencing any "denim blues" related to his jeans-meets-gym workouts, he might want to make sure he's keeping those jeans clean. Dermatologist Dr. Erum N. Ilyas advises washing jeans pretty promptly after they get sweaty, but that isn't always a foolproof plan either, especially for someone who goes straight from the gym to everyday activities without throwing them in the wash (via Everyday Health). Said Dr. Ilyas, "Denim is still mostly cotton, although we are finding some more use of blended textiles that include an elastane to make it stretchier. The bacteria can embed itself into textiles and even form biofilms to resist washing if left unwashed for too long."