One day, Mr. K, a 55-year-old man, proudly told me he had finally succeeded in losing weight. He had gone from 95kg to 85kg over the previous two months. His secret was to eat only one meal a day. But he was not sure about how long he could maintain this diet, did not do any physical exercise. So is this a desirable method for weight control?

Obesity is becoming increasingly prevalent worldwide. It is linked to health problems including cardiovascular disease, diabetes, cancer, musculoskeletal problems and even psychiatric problems. However, it is difficult to manage even though most people recognize the importance of maintaining a healthy weight.

There could be several reasons for that. First, plenty of delicious foods, easily accessible transportation and a reduced physical activity level in daily life hamper efforts for weight control. Second, it is very difficult to maintain a reduced weight due to some physiologic mechanisms in the human body. The so-called yo-yo phenomenon, where those who lose weight tend to gain it back or gain even greater weight, is very common. Third, achieving big weight loss in a very short period is likely to cause serious adverse health problems such as gall stone disease, electrolyte and nutrient imbalances, and decreased muscle volume.

To overcome these obstacles and achieve healthy weight control, there are several things to keep in mind.

Obesity usually results an energy imbalance in our body. Several factors in our daily life contribute to change in the energy balance. Simply speaking, food intake causes energy acquisition, whereas functions or activities such as household chores or physical exercise cause energy expenditure. In order to lose weight, we should try to make the energy balance negative by reducing food intake and increasing physical activity.

Although medication can help, it is difficult to lose weight, and almost impossible to maintain a reduced weight, without reducing food intake or increasing exercise.

Think of all benefits from weight loss: A better figure, less knee joint pain, reduced shortness of breath when going upstairs, etc.

A desirable rate of weight loss is about 2-3kg per a month. Greater weight loss may bring adverse side effects. By reducing food intake by 500 calories per day, you can lose 2kg a month.

We should be aware that not only a high-fat diet, but also a high-carbohydrate diet including sugar and starch (abundant in flour, rice, potato, sweet potato, corn, etc.), can induce weight gain. Increase the intake of vegetables or low-fat, protein-rich food.

Eat a reduced amount of well-balanced food regularly. Having breakfast is essential and the amount eaten in the evening should be reduced. Midnight snacks should be avoided. A very-low-calorie diet, less than 800 calories per day, can cause serious health problems and should only be done under the very close guidance of an expert physician.

Alcohol is a source of energy that does not supply any helpful nutrients. One gram of alcohol provides 7 calories of energy, which is much greater than the 4 calories per 1 gram of carbohydrate or protein. Therefore, giving up alcohol is essential to lose weight.

Even though physical activity increases energy expenditure, weight loss by exercise alone is not so effective. However, it enhances dietary adherence and efficiency, and so can help keep the weight off.

In conclusion, is Mr. K’s method desirable for weight control? No. Our final goal of weight control should be good health rather than just losing weight for a short period. A shape-based focus or weight-based focus can be sometimes physically and psychologically catastrophic.

By Song Yun-Mi MD, PhD.

The author is a professor at the Department of Family Medicine at Samsung Medical Center and Sungkyunkwan University School of Medicine. ― Ed.