Do not use extreme dieting, fasting, or self-induced vomiting to control weight; if you want to lose weight, focus on exercise instead

Cost: No cost at all. In fact, it saves money you would otherwise spend on weight-loss products.
In plain terms: People with anorexia nervosa have a mortality rate roughly 5.9 times higher than their peers. Over a period of one year, 5.1 out of every 1,000 individuals in this group die. One in five of those who die commit suicide. The root cause of this is dieting: a three-year study of students at 44 secondary schools found that girls who engaged in severe dieting were 18 times more likely to develop eating disorders than those who did not diet. If you want to manage your weight, increase physical activity rather than cutting food intake to the point of hunger.
Benefit: This conclusion comes from a combined analysis of 36 studies that tracked a total of 166,642 person-years of data on individuals with anorexia nervosa. Their standardized mortality ratio was 5.86, meaning their mortality rate is about 5.9 times higher than that of the general population. As noted above, 5.1 deaths occur per 1,000 person-years, and roughly one-fifth of these deaths are suicides. For bulimia nervosa, the standardized mortality ratio is 1.93, and for other eating disorders it is 1.92 — both values are roughly 1.9 times higher than those of the general population. Another study conducted in 44 secondary schools in Victoria, Australia, followed 14–15-year-old students for three years, with six rounds of assessments during that time. It found that 21.8 new cases of eating disorders occurred per 1,000 person-years among girls; girls who dieted severely were 18 times more likely to develop such disorders than those who did not, while those with moderate dieting habits had an 5 times higher risk. After adjusting for prior dieting habits and existing mental health issues, factors such as BMI, physical activity levels, and gender no longer predicted the development of eating disorders. The authors concluded that for adolescents, using exercise rather than diet restriction to manage weight appears to lower the risk of developing eating disorders.
Evidence grade: A
Sources:Arcelus J et al. (2011). Mortality rates in patients with anorexia nervosa and other eating disorders. A meta-analysis of 36 studies. Arch Gen Psychiatry. https://doi.org/10.1001/archgenpsychiatry.2011.74；Patton GC et al. (1999). Onset of adolescent eating disorders: population based cohort study over 3 years. BMJ. https://doi.org/10.1136/bmj.318.7186.765
Notes: The term “severe dieting” here refers to long-term food intake that is far below the body’s actual needs; it does not include skipping a single meal or foregoing late-night snacks. If you or someone you know exhibits symptoms such as self-induced vomiting, feelings of guilt after binge eating, or an inability to stop weighing oneself, it is recommended to seek help from a psychiatrist or a clinical psychology department at a general hospital. This is a medical condition with established treatment methods, and it is not a matter of lacking willpower. For information on the relationship between BMI and mortality, please refer to Section 2, Item 32, which discusses long-term weight ranges rather than weight-loss methods.