Hong Yoon-hwa's yo-yo after losing 40 kg: 'So cold my hands shook' [Their Health Aesthetics]

Comedian Hong Yoon-hwa has shared her experience of losing a dramatic 40 kilograms over nine months, describing a range of abnormal symptoms and a subsequent weight rebound. Her account has drawn attention to how a rapid, large-scale diet can burden the body.

Hong recently appeared on SBS's variety show Dongsangimong 2 - Neoneun Nae Unmyeong ("You Are My Destiny"), where she showed off a gold bracelet her husband had given her to celebrate her past weight-loss success. Noting that the bracelet now fit more tightly than before, she cheerfully revealed that she had regained weight, saying, "I've been living a little too happily lately."

But even during her successful 40-kilogram weight loss, her body had shown no shortage of warning signs.

Hong once met with Oh Sang-woo, a family medicine specialist and obesity expert who is a professor at Dongguk University Ilsan Hospital, and told him, "After losing 40 kilograms over nine months, my body feels very tired. I'm not depressed, but I've become much calmer, and my body has changed so much that it feels unfamiliar."

She said that although she had rarely felt cold before, after the weight loss she felt so cold that her hands would tremble. She also reported experiencing tinnitus, dizziness and insomnia, as well as bruises that took a long time to fade.

At the time, Oh explained that this could be the body's way of adjusting to such a large drop in body fat. When Hong mentioned that she had regained 4 kilograms after eating more to nourish her body, he said, "That is exactly the start of a yo-yo effect." He also stressed the need to avoid repeating the cycle of losing a large amount of weight only to regain it.

More weight loss is not always better. Particularly when a person drastically cuts food intake over a short period to quickly bring down the number on the scale, the body can lose muscle and water along with fat, throwing its overall balance off.

The Korean Society for the Study of Obesity's clinical guidelines recommend an initial goal of losing about 5 to 10 percent of pretreatment body weight within six months when starting obesity treatment. For someone weighing 100 kilograms, that means aiming to lose around 5 to 10 kilograms at first. The appropriate pace can vary depending on a person's degree of obesity, underlying conditions and treatment method. Still, Hong's 40-kilogram loss over nine months represents a considerably bigger change than the typical initial weight-loss target.

When calorie intake is cut too sharply, the body adapts by lowering its energy expenditure to match the reduced supply. As body weight itself decreases, less energy is needed than before, and a decline in muscle mass can further lower basal energy expenditure.

The problem emerges after the diet ends. Even when a person returns to a pre-diet eating pattern, the now-lighter body may need less energy than it once did. If food intake increases quickly under these conditions, the surplus energy gets stored as fat, making it easy for weight to climb again — one reason the so-called yo-yo effect occurs.

When a diet leads to deficiencies in specific nutrients, the problems go beyond weight alone.

Insufficient intake of iron and various vitamins and minerals can cause fatigue or dizziness. If food intake drops sharply enough to cause low blood pressure or dehydration, a person may experience orthostatic dizziness — a blackout sensation upon standing up.

Some people become more sensitive to cold after a large drop in weight and subcutaneous fat. When insufficient calorie intake is combined with nutritional imbalance, lethargy and fatigue can become even more pronounced.

Easy bruising, or bruises that linger longer than usual, should not simply be dismissed as a byproduct of weight loss. Because such symptoms can stem from a range of causes, including nutritional deficiency, they should be checked by a doctor if they recur.

Rapid weight loss can also raise the risk of gallstones, as changes in bile composition and gallbladder motility during fast weight loss can make stone formation more likely. Extreme food restriction that leads to deficiencies in protein and micronutrients can also trigger telogen effluvium, a form of hair loss in which large amounts of hair fall out at once. This typically appears months after the restriction began.

The goal of obesity treatment is not to lose as much weight as possible in as short a time as possible. Losing even a relatively small percentage of one's current body weight can improve metabolic markers such as blood pressure, blood sugar and triglycerides.

What matters more is building a lifestyle that can sustain the weight loss without regaining it. An approach of extreme food restriction followed by a return to old eating habits once a target weight is reached is difficult to sustain over the long term.

It is advisable to ensure sufficient protein, vegetables and essential nutrients in one's diet while pairing it with physical activity suited to one's fitness level. Minimizing muscle loss is also important for managing weight after a diet ends.

What determines whether a diet succeeds is not how quickly one reaches the lowest number on the scale. The key to healthy weight loss lies in shedding weight at a pace the body can handle and being able to sustain that state over the long term.