Actor Choi Jeong-won, 55, on surviving on 100g of chicken breast a day — and why the weight came back

Actor Choi Jeong-won, 55, has drawn attention after revealing she once followed an extreme diet that at its most restrictive left her eating just 100 grams of chicken breast a day. She lost 9 kilograms in three months and drove her body fat percentage down to a single digit — but said the weight eventually came back. Experts warn that severe caloric restriction can alter appetite and energy expenditure after weight loss, and stress that preserving muscle mass while managing weight is especially important in middle age.

Choi appeared on TV Chosun's "Perfect Life," which aired Wednesday, and said menopause caused her weight to jump by 8 to 9 kilograms at once. Tests at the time showed her inflammation markers at more than twice the normal range, she said, which made her realize she needed to take her health seriously.

Sharing body-profile photos taken about four years ago, Choi recalled losing 9 kilograms over three months. "There were days I got through on just 100 grams of chicken breast," she said, describing how hard it was to give up the pleasure of eating.

Asked whether she had maintained that physique, she laughed and said, "Of course not — weight you lose in a hurry comes right back." She added that as she has gotten older, changes in her digestion have made it difficult to follow such an extreme diet as she once did.

Surviving on 100g of chicken breast: fat loss comes with muscle loss

Losing weight requires burning more energy than the body takes in. Drastically cutting food intake can produce rapid weight loss in the short term, but the pounds shed in that process include not only body fat but also muscle and water.

Diets that rely too heavily on a single food — chicken breast being a prime example — also tend to create nutritional imbalances. Chicken breast is a high-quality protein source, but it cannot on its own meet the body's needs for carbohydrates, fat, dietary fiber, vitamins and minerals.

When the body is in a prolonged state of severe caloric deficit, it draws on stored fat and muscle protein alike to meet its energy needs. As muscle mass falls, so does the strength needed for everyday physical activity, and resting energy expenditure can decline along with body weight.

A 2023 study published in the international journal Advances in Nutrition examined how different weight-loss methods affect body composition in middle-aged and older adults.

Researchers reviewed 92 randomized clinical trials involving overweight and obese adults aged 55 to 70, drawing on data from 66 of those trials — covering 4,957 participants — for a network meta-analysis.

Caloric restriction proved effective at reducing body fat, but it also tended to reduce muscle mass. Combining dietary changes with resistance training, however, helped participants lose fat while preserving muscle. Increasing protein intake alongside exercise also produced improvements in body composition.

The researchers noted that muscle loss during weight reduction raises the risk of sarcopenic obesity in middle-aged and older adults — a condition in which excess body fat accumulates alongside insufficient muscle mass or strength.

The National Institute for Health and Care Excellence (NICE) recommends that very-low-calorie diets of fewer than 800 kilocalories a day be used only within specialist obesity management programs under medical supervision. Such diets must be nutritionally balanced, NICE advises, and should not be used as a long-term weight-management strategy.

Lost 9kg, then regained it: the role of appetite hormones

Returning to a previous weight after losing it is not simply a matter of eating habits — it is also tied to physiological changes in the body. As weight falls, the body adapts to an energy-deficient state by altering the secretion of hormones that regulate appetite and energy expenditure.

Two key hormones are leptin and ghrelin. Leptin, produced mainly by fat cells, signals the brain about the body's energy stores and plays a role in appetite regulation. Ghrelin, secreted primarily in the stomach, triggers feelings of hunger.

Weight loss can lower leptin levels and raise ghrelin levels — one reason people often feel hungrier than usual and more preoccupied with food even after they have finished losing weight.

A 2011 study published in The New England Journal of Medicine tracked changes in appetite-related hormones following weight loss.

Australian researchers put 50 overweight and obese adults on a very-low-calorie diet for 10 weeks, then compared hormone levels and appetite immediately after weight loss and again about a year later.

Participants lost an average of 13.5 kilograms. Immediately after the weight loss, levels of satiety-related hormones including leptin fell while ghrelin — which stimulates appetite — rose, and participants reported stronger feelings of hunger.

Notably, these changes persisted well beyond the weight-loss period. Measurements taken about a year later showed that levels of leptin, ghrelin and several other hormones still differed from pre-weight-loss values, and hunger remained elevated.

The findings suggest the body continues to adapt to its reduced weight long after the loss itself. When that adaptation is compounded by a drop in daily energy expenditure, maintaining the lower weight requires ongoing adjustments to both food intake and physical activity.

The US Centers for Disease Control and Prevention says people who lose weight gradually — at a rate of roughly 0.45 to 0.9 kilograms per week — through healthy eating and regular physical activity are more likely to keep the weight off over the long term.

That is why establishing sustainable eating habits and an exercise routine that can be maintained after weight loss matters as much as the loss itself.

Managing weight through menopause: muscle preservation matters more than eating less

Menopause — the period Choi said coincided with her weight gain — is also a time of shifting body composition in women. Declining estrogen changes the way fat is distributed, making it easier for fat to accumulate around the abdomen. Combined with the age-related loss of muscle mass and reduced physical activity, these changes can make weight management increasingly difficult.

Muscle does more than power movement — it also plays an important role in regulating blood sugar. As muscle mass and strength decline, physical capacity can suffer, which is why women in middle age and beyond are advised to monitor not just the number on the scale but also body fat and muscle mass.

The benefits of resistance training are well documented. A meta-analysis published in 2024 in the Journal of Sport and Health Science analyzed 20 randomized clinical trials involving overweight and obese postmenopausal and older women.

The group that performed resistance training showed greater improvements in body fat and metabolic health markers than the group that did not exercise. Positive changes were observed particularly in blood sugar levels and in C-reactive protein, a marker of inflammation.

The researchers found that greater volumes of resistance training were associated with larger improvements in blood sugar and inflammation markers. Because exercise programs and participants' health conditions varied across studies, however, they emphasized the importance of choosing an exercise intensity suited to each individual's fitness level.

For weight management in middle age and beyond, combining adequate protein intake with resistance training is recommended. Drawing protein from a variety of sources — eggs, fish, meat, tofu and legumes — alongside vegetables, whole grains and fruit helps maintain nutritional balance.

Exercise can begin with movements that engage large muscle groups, such as squats, lunges and resistance-band exercises. Gradually increasing the workload in line with one's strength and joint condition, and pairing resistance work with aerobic activity such as walking, supports both body fat management and cardiovascular health.

After losing weight, the priority shifts from continued reduction to stable maintenance. Rather than severely restricting food intake, building regular meals and physical activity into daily life — and keeping track of body composition alongside routine health check-up results — supports long-term health.