Behind every public figure's appearance lies a personal regimen. This series examines the diets, workouts, treatments, and beauty and fashion routines of people in the spotlight.
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Actor Ko Kyung-pyo, 36, has revealed that a trip to London added 4 kilograms to his frame, bringing his weight back up to 90 kg. Ko said the gain came after indulging in a variety of foods while traveling. Experts note, however, that a rapid short-term weight increase reflects not only body fat but also changes in the body's water content, glycogen stores and the weight of food still moving through the digestive tract.
Ko appeared by phone Wednesday on "Bimil Bojang," a web variety show on the YouTube channel Bibo TV, where he shared his recent weight changes. "I had lost about 4 kilograms, but then I went to London for a bit," he said. "I came back having hit 90 kg again."
He added that he had visited Greek restaurants frequently and eaten burgers, tiramisu and many other foods during the trip. Ko, who said he trims his weight to the low 80s or even the 70s in kilograms depending on a role, noted that doing so seriously takes about two months. He also admitted that crash fasting to lose weight had taken a toll on his body.
Sudden weight gain after a period of unusual eating — whether during travel or a holiday — is common. Changes in carbohydrate and sodium intake can shift the body's fluid levels, causing the number on the scale to move quickly.
The figure on a scale represents the combined weight of everything that makes up the body: fat, muscle, bone, water and more. A jump in body weight does not mean all the added weight has been stored as fat.
Glycogen is one of the main factors behind short-term weight fluctuations. It is the form in which the body stores glucose derived from carbohydrates, accumulating primarily in the liver and muscles and drawn upon when energy is needed.
Glycogen storage carries a significant amount of water with it. It is generally understood that for every gram of glycogen stored in muscle, roughly 3 grams of water are stored alongside it. This is why an increase in carbohydrate intake — and the resulting rise in glycogen stores — can add to body weight even when body fat has barely changed.
Research supports the idea that a substantial portion of short-term weight change comes from components other than fat.
A study published in 2017 in the journal Physiological Reports analyzed changes in body weight and composition over two weeks in 46 adults going about their daily lives.
Researchers measured participants' body weight, total body water and fat mass, among other metrics. About 84 percent of short-term weight changes were found to be associated with changes in lean body mass.
Lean body mass refers to everything in the body except fat — muscle, water, bone and the like. The researchers concluded that glycogen, the water it binds and food remaining in the digestive tract all contribute to short-term weight fluctuations.
Sodium intake is another important factor. Eating saltier food than usual can temporarily increase the body's water content and push up body weight. The puffiness in the face, hands and feet — and the higher number on the scale — that often follow a day of heavy carbohydrate and sodium consumption are linked to these same changes.
How much body fat actually increases depends on the length of the trip, how much was eaten and how active a person was. The scale alone cannot distinguish how much of the gain came from fat versus water.
Travel tends to bring more frequent meals and larger quantities of food eaten at once. Foods like the burgers and tiramisu Ko mentioned — rich in fat and sugar — can deliver a large number of calories in a small portion.
The taste, texture and energy density of food all influence how much a person eats. Encountering a wider variety of dishes than usual, or adding dessert after a full meal, makes it easy to take in extra calories even when already full.
Clinical research has also shown that the degree to which food is processed affects actual calorie intake and weight change.
A study by the US National Institutes of Health published in 2019 in the journal Cell Metabolism compared an ultra-processed diet with an unprocessed diet in 20 adults.
Researchers provided participants with each diet for two weeks while they stayed at a research facility. Both diets were matched for total calories, key nutrients, sugar, sodium and dietary fiber, and participants were free to eat as much as they wanted.
Participants consumed an average of 508 kilocalories more per day during the ultra-processed diet period than during the unprocessed diet period. Body weight also increased by an average of 0.9 kg over the two weeks on the ultra-processed diet, while it fell by an average of 0.9 kg on the unprocessed diet.
The researchers concluded that the degree of food processing and the characteristics of individual foods can influence calorie intake and body weight. Choosing foods that are calorie-dense or easy to eat quickly can increase total consumption even when the same volume of food is consumed.
To limit weight gain while traveling, it helps to look at the overall quantity and composition of meals rather than cutting out every desired food. On days when dessert is on the menu, reducing other snacks and making sure meals include adequate protein and vegetables can help maintain a sense of fullness while keeping nutrition in balance.
Some people resort to extreme calorie restriction after returning from a trip to shed the weight they gained. If water retention is part of the reason for the gain, however, simply returning to normal eating and activity patterns may be enough to bring some of that weight back down naturally.
Severely restricting calorie intake to lose weight quickly can reduce not only body fat but also lean tissue such as muscle. People whose weight repeatedly goes up and down should pay particular attention to how their body composition changes during the weight-loss process.
A randomized clinical trial published in 2016 in the journal Obesity compared physical changes based on the rate of weight loss in 57 overweight or obese adults.
Researchers divided participants into a group that consumed 1,250 kilocalories per day and lost weight over 12 weeks, and a group that followed a very-low-calorie diet of 500 kilocalories per day and lost weight over five weeks. Body weight and composition were then analyzed after a weight-maintenance period and nine months of follow-up.
The two groups lost an average of 8.2 kg and 9.0 kg, respectively. There was no significant difference in long-term weight regain between the groups based on the rate of loss, but the very-low-calorie group showed a higher proportion of lean mass loss.
The researchers noted that participants who lost more lean mass during the weight-loss phase tended to regain weight more readily afterward — a finding that underscores the importance of considering both fat and muscle when trying to lose weight.
The US Centers for Disease Control and Prevention recommends balanced meals, regular physical activity and adequate sleep for healthy weight loss. It generally advises a gradual reduction of roughly 0.45 to 0.9 kg per week as the approach most conducive to keeping weight off over the long term.
After gaining weight on a trip, the best first step is to return to normal eating patterns and monitor changes over several days. Weighing yourself at roughly the same time and under the same conditions each day, and tracking trends over a period of time rather than fixating on a single day's number, gives a more accurate picture.
Combining moderate calorie control with strength training can help preserve muscle mass while reducing body fat. Increasing everyday physical activity — such as walking or cycling — and consuming sufficient protein are also important.
A short-term increase in body weight may reflect a combination of changes in body fat, water and glycogen. Rather than focusing solely on the difference in weight before and after a trip, returning to healthy eating habits and monitoring changes in body composition is the more effective approach to long-term weight management.
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