Ahn Jae Hyun Reveals 1,000-Rep Ab Routine After Gaining 17kg for an Acting Role

The actor says his clothes required major alterations after recent weight loss, but he has not disclosed his current weight

Ahn Jae Hyun has opened up about another dramatic physical transformation after previously gaining 17 kilograms for an acting role.

In a video uploaded to his YouTube channel on October 5, the actor explored his regular spots in Seoul’s Seongsu neighborhood and discussed his recent weight loss.

While walking to a dry cleaner, Ahn unexpectedly met his mother, who immediately expressed concern about his slimmer appearance. He reassured her that he was eating properly before continuing to explain how significantly his body had changed.

“I lost a lot of weight,” he said, adding that several pairs of pants had to be taken in by approximately three inches.

The alteration offers a clearer indication of his changing body measurements than the scale. Ahn did not reveal his current weight, meaning it would be inaccurate to suggest that he has lost the full 17 kilograms he previously gained.

Why Ahn Jae Hyun Gained 17kg

Ahn previously discussed his weight transformation during an April appearance on KBS2’s “Problem Child in House.”

The actor said he had weighed approximately 60 kilograms while actively preparing for projects. However, after accepting a drama that required a more muscular physique for an intimate scene, he began gaining weight and building his body.

When asked about his weight at the time of the program, Ahn answered that he had reached 77 kilograms. The difference between his earlier filming weight and that figure was approximately 17 kilograms.

His comments indicated that the change was connected to a professional goal rather than ordinary fluctuation. He needed to create a visibly larger frame for the character, combining increased body weight with strength training.

Ahn has since entered another phase of body management, documenting both his meals and workouts through his YouTube channel.

Inside His Strict Diet and Workout Routine

In a September video, Ahn said he was still following a structured diet but stressed that he had not completely removed carbohydrates.

His meals included a balance of carbohydrates, protein and fat, with examples such as chicken breast, sweet potato and a small portion of nuts.

The explanation challenged the common idea that weight loss requires eliminating carbohydrates entirely. Ahn instead focused on controlled portions and consistent meal planning.

His exercise schedule was even more intense. In a separate workout video, he claimed to visit the gym seven days a week and complete 1,000 abdominal exercises each day.

His reason was direct: he wanted his abdominal muscles to become visible.

Ahn also incorporated cardio into his routine. He explained that completing his workout, showering and eating could take up a large portion of the day, showing how much time his physical preparation requires.

Why 1,000 Ab Exercises Are Not a Universal Formula

Ahn’s routine reflects the demands placed on an actor preparing his body for the camera, but it should not be treated as a standard program for everyone.

Performing 1,000 abdominal repetitions every day is an unusually high training volume. Individual routines should account for experience, technique, recovery time, physical condition and personal goals.

Visible abdominal definition is also influenced by overall body composition and nutrition, not simply the number of abdominal exercises performed.

General health guidelines focus on balanced activity rather than prescribing an extreme number of repetitions. The World Health Organization recommends that adults complete 150 to 300 minutes of moderate aerobic activity per week, or 75 to 150 minutes of vigorous activity. It also recommends muscle-strengthening exercise involving the major muscle groups on at least two days each week.

Ahn’s own diet similarly emphasizes balance rather than relying on a single food restriction or exercise.

A Transformation Measured Beyond the Scale

Ahn Jae Hyun’s latest update is not simply a celebrity weight-loss story. It shows how an actor’s body may change repeatedly to meet the visual demands of different projects.

He first moved from approximately 60 kilograms to 77 kilograms while preparing a stronger, more muscular physique. He has now lost enough weight to require substantial alterations to his wardrobe, although his latest weight remains unknown.

The most revealing detail may not be the original 17-kilogram difference or the 1,000 daily abdominal repetitions. It is the level of consistency required to reshape his body again through planned meals, resistance training and cardio.

His routine is highly personal, but the broader principle is more widely applicable: sustainable body management depends on the complete pattern of nutrition, training and recovery, not one dramatic number.