When it comes to the perfect male physique, our thoughts often return to a certain Hollywood icon’s V-line abs in Fight Club. There’s good reason Brad Pitt’s body in that movie inspired a TikTok trend: he’s lithe yet muscular, slim but with some size. And, of course, he has the prized V-line shape to his abs. You may also remember a similar set of muscles from that era, on the singer D’Angelo in his video for “Untitled (How Does It Feel).” They’re the ultimate sign of a dialed-in fitness routine. But just what are they, and how can you get them? What are V lines? “V lines are where the obliques meet the transversus abdominis muscles. They are only visible when you have a very low body fat percentage, which can either mean 11% or lower for men, and 14% or lower for women,” explains David Wiener, a training and nutrition specialist at the AI-based fitness coaching app Freeletics. Wiener says that V lines are “highly sought after”—and require a lot of effort and commitment to achieve. Doing 50 sit-ups …