Nobody Knew Seong Hanbin Was Nearly 100kg Before Debut

Most K-pop fans know Seong Hanbin as the main dancer of ZEROBASEONE — precise, powerful on stage, and built for the kind of performance that fills arenas. What far fewer people knew, until this week, is that the same person once came close to weighing 100 kilograms.

Seong Hanbin made his first solo appearance on JTBC's long-running variety show 'Knowing Bros' on May 2, joining a special "Dance Masters vs. Vocal Masters" episode alongside Highlight's Lee Gi-kwang, former Sistar member Soyou, and B1A4's Sandeul. It was Hanbin's first time on the show — a fact he noted himself, saying he felt both excited and slightly envious that other ZEROBASEONE members had already been through the experience without him. By the end of the episode, those members probably had a few new questions for him on the group chat.

The Lie Detector That Wasn't a Lie

The moment that took the studio by surprise came during a regular 'Knowing Bros' segment called "Hanbin's Lie Detector," in which the other cast members try to identify which of the guest's statements is false. Seong Hanbin told the cast he had been a competitive climber for three years in middle school — a claim that sounded plausible given his athleticism and body control. It turned out to be false.

The true story, which surfaced moments later, was more layered. Seong Hanbin revealed that it was actually his younger sister, Seong Han-areum, who is the competitive speed climber in the family — not him. He had started climbing alongside her as a recreational activity, but stopped because he was too heavy to keep up. At that point in his life, he recalled, his weight had climbed to close to 100 kilograms.

The cast's reaction landed somewhere between shock and disbelief. Min Kyung-hoon had already raised an eyebrow when the climbing claim came up — pointing out that high body weight and vertical climbing are not a natural combination. Lee Sang-min followed the logic directly: "So you were just there watching, and your sister was the actual athlete." Seong Hanbin confirmed it. He had done some climbing, but the weight made it difficult, and eventually he stepped back from it entirely.

The Perfume Diet and a 30-Kilogram Turnaround

The natural follow-up question was how Seong Hanbin went from 100 kilograms to the 64-kilogram, 180-centimeter performer that fans know today — a transformation of roughly 30 kilograms. His answer was one of the episode's more memorable moments.

Seong Hanbin said he started using a method he described as a "perfume diet": applying fragrance specifically to suppress his appetite, using the smell as a sensory override when food cravings hit. He described it matter-of-factly, as if this were a completely obvious solution to an obvious problem. The cast's response was less matter-of-fact. The combination of the method's specificity and Hanbin's casual delivery created the kind of comedy that 'Knowing Bros' specializes in — something real and a little unexpected, arriving without warning.

The 30-kilogram loss represents a significant physical change across what appears to have been his late pre-debut training years — a period in which aspiring K-pop performers often face intense physical conditioning alongside the rest of their preparation. For Seong Hanbin, who entered his idol career as a former professional dancer and choreographer, that transformation was clearly part of building the performer he became.

Dance, Tutting, and a Set That Lit Up the Studio

The weight loss story was only one part of what made the appearance memorable. Seong Hanbin arrived with the kind of performance-first attitude that 'Knowing Bros' rewards, and he delivered early and often.

His entrance featured an unconventional self-introduction built around a live performance — part personality showcase, part demonstration of why his dance reputation precedes him. He then performed a tutting routine, a finger and hand isolation technique that had previously drawn significant attention online, followed by a medley of ZEROBASEONE hit songs that showed his range as a performer well beyond any single style.

Later in the episode, in an AI Picture Lyrics Quiz segment where contestants identify songs from AI-generated images of their lyrics, Seong Hanbin added another layer. After getting a correct answer, he performed a full dance celebration routine on the spot, pulling from whatever was available to him in real time. The studio reacted the way it tends to when someone who can actually dance decides to show you what that means in an unscripted setting.

Cast and guests described him as someone who settled into the show's dynamic quickly for a first-time visitor, trading well with the regulars and finding a comfortable chemistry with Lee Gi-kwang — another dancer — in particular. Kim Shin-young, who recently joined 'Knowing Bros' as a permanent cast member, noted she had been following Seong Hanbin's work and made a point of introducing him warmly to the audience.

What's Coming: ZEROBASEONE's Comeback

Seong Hanbin used the platform to preview what his group has planned for the near future. ZEROBASEONE — the five-member lineup of Seong Hanbin, Kim Ji-woong, Seok Matthew, Kim Taerae, and Park Gunwook — is scheduled to release their sixth mini-album, 'Ascend-,' on May 18 at 6 p.m. KST across all major music platforms.

The group described the upcoming release as a step forward in terms of identity and cohesion — built on a "solidified" group sound and tighter teamwork developed over the course of their career so far. For a group that was formed through the survival competition format of Mnet's 'Boys Planet' in 2023, 'Ascend-' represents their sixth full release across roughly two years of activity, which speaks to a sustained output that has kept them consistently visible in the K-pop market.

Seong Hanbin's appearance on 'Knowing Bros' lands roughly two weeks before the release, at a point in the promotional cycle when building broader public awareness matters. His combination of candid personal stories and demonstrated performance skill made for an effective preview of what the comeback is likely to look like: a group with strong individual personalities and the stage chops to match whatever concept they're given.

A Slightly Different Side of the Main Dancer

What the episode offered, beyond the anecdotes and the performances, was a version of Seong Hanbin that ZEROBASEONE fans see in behind-the-scenes content but that general audiences rarely get access to in a long-format setting.

He came across as someone who is comfortable with himself — willing to share genuinely surprising information about his past without dramatizing it, and capable of finding the humor in his own story. The 100-kilogram revelation was not positioned as a struggle narrative or a redemption arc. It was simply a fact about where he came from, offered in the same matter-of-fact register as the perfume diet and the climbing story. The audience seemed to appreciate the lack of performance around it.

The episode of 'Knowing Bros' aired on JTBC on May 2. ZEROBASEONE's 'Ascend-' drops on May 18.