For health and longevity, exercise is more beneficial than weight loss. Even if you increase the amount of exercise, you may fail to lose weight. However, exercise is more effective to reduce mortality than going on a diet. When obese or overweight people start exercising, their premature mortality rates can go down by more than 30 percent. The benefits of exercise are evident even without a significant change in body weight. However, the effect of going on a diet is not clear. In some cases, the mortality rate increases, and even when the mortality rate decreases, the extent was not large compared to the effect of exercise.

Why is this so? The answer is in the yo-yo effect, described in a 2021 review paper by Glenn Gaesser, professor of exercise physiology at Arizona State University. Even if you lose weight hard, the vicious cycle of gaining weight again continues, making it easy to suffer from health problems due to dieting. Anyone who has ever been on a diet knows how difficult it is to maintain weight.

Appetite is crucial for survival. It cannot be forced to go away. Psychologists Peter Herman and Janet Polivy conducted an interesting experiment on this in the 1970s. Participants were asked to drink a high-calorie milkshake and then to taste and rate cookies, cakes, and nuts. Since it was after the milkshake, most participants ate less of other foods. However, people on a diet did the opposite. After drinking the milkshake, they ate even more cookies, cakes, and nuts at the tasting. The psychology of thinking, “Oh well, screw it, I already overate so I’ll just eat more,” seemed to have worked.

In another experiment, participants were given a 300 kcal snack but told the food had 600 kcal, and the other way around, a 600 kcal snack with misinformation of 300 kcal. Afterward, they were given sandwiches for a meal. People on a diet showed similar behavior. After perceiving that the snack had high calories, they ate more sandwiches. But those who thought they had eaten a low calory snack ate less. Regardless of the actual calorie intake, participants ate excessively with the thought that they have already failed in dieting. Adults, who are always obsessed with eating less, act in the opposite way to children who eat less because they are full after snacking. However, if you do not listen to the physiological signals of the human body and consciously press it, the moment of overeating will come instantly. Then, the diet fails and the belly fat grows back. Then, your health deteriorates more than before.

You may say you already know exercise is good but you lack willpower. When that happens, think of death. According to a 2021 study from the University of Waterloo, Canada, messages about the risk of disease and death due to lack of exercise were the most effective in motivating exercise. Just thinking that “if you don't exercise, you'll get sick and die quickly” is a powerful motivator. Let go of the desire for a slim body and start thinking about surviving first, healthily.

Jeong Jae-hoon is a food writer and pharmacist. He covers a variety of subjects, including trends in food, wellness and medications. This column was originally published in Korean in Joongang Ilbo on Jan.19, 2022. – Ed.