Actor Park Ji-hoon has become a major talking point following the revelation that he lost 15kg in just two months to portray the exiled King Jeongjong in the film The King's Warden.
Appearing recently on tvN’s You Quiz on the Block, Park shared the grueling details of his transformation. "I survived on just one apple a day to capture the physical toll of King Jeongjong’s exile," he revealed. Despite his self-professed love for food, Park felt the deprivation was a creative necessity. "I believed I needed to actually feel that hunger for the emotion to show authentically on my face," he recalled, adding that he endured the process with a singular focus on the role.
Park’s performance, characterized by a pale, gaunt physique and a delicate portrayal of the King’s suffering, has sparked what fans are calling "Jeongjong Syndrome." This recognition for his acting depth—moving beyond his origins as an idol—was built on extreme self-discipline. Interestingly, Park noted that his choice of fruit was strategic: "I chose apples to suppress my appetite specifically because they are the fruit I dislike the most."
While such rapid transformations are common in the entertainment industry, they raise significant medical concerns. A single apple provides approximately 80 to 100 kcal, a fraction of the recommended daily intake for an adult male. While the scale reflects rapid weight loss, experts warn that much of that decrease likely comes from muscle mass and water rather than just body fat.
The Science and Limitations of the "One Apple" Diet
Apples are objectively healthy in a balanced context; they are rich in water and dietary fiber, which provide satiety. Specifically, soluble fibers like pectin slow digestion and help moderate blood sugar spikes. Despite their natural sugars, their high water content makes them relatively low in caloric density.
When caloric intake is severely restricted over a short period, the body first exhausts its stored glycogen and water, leading to the rapid drop in weight Park experienced. Additionally, the act of chewing a fibrous apple can trigger satiety signals, and consuming the skin provides essential antioxidants.
However, relying on a single fruit is biologically unsustainable. An apple lacks the protein and essential fatty acids required for basic bodily functions. Under such extreme deficit, the body begins to break down muscle protein for energy, which significantly lowers the basal metabolic rate and makes long-term weight maintenance nearly impossible.
The Risks of "One-Food" Dieting and the Yo-Yo Effect
The "one-food diet" is often tempting due to its simplicity, but it carries a high risk of severe nutritional imbalance. A chronic lack of protein leads to muscle wasting, while deficiencies in iron, calcium, and healthy fats can cause chronic fatigue and a weakened immune system. Prolonged adherence to such a restrictive regime can also lead to clinical symptoms such as hair loss or hormonal irregularities.
Furthermore, extreme caloric restriction frequently triggers a psychological and physiological rebound, often leading to binge eating and the "yo-yo effect" once the diet ends. Medical experts emphasize that while Park Ji-hoon’s transformation was a professional choice for his craft, it is not a viable health strategy for the general public. Safe weight loss requires a gradual reduction in calories paired with adequate protein intake and consistent strength training to preserve metabolic health.
