Introduction: It is an accepted fact that obesity can cause disease and harm health, but people may not have a clear idea of the extent of this harm. A recent study published in The Lancet Diabetes & Endocrinology quantified the dangers of obesity: the study concluded that severe obesity can reduce life expectancy by up to eight years. Moreover, obese people may remain healthy for more than 10 years less than those of normal weight. The researchers used data from the National Health and Nutrition Examination Survey to develop a computer model to assess the risk of diabetes and cardiovascular disease among adults of different weights. The study also analyzed how life expectancy changed among obese or overweight adults in the United States compared to those of normal weight. Steven Grover, an epidemiologist at McGill University in Canada and author of the paper, explained, “Our computer simulation study shows that obesity is associated with an increased risk of developing cardiovascular disease and diabetes and, as a result, significantly reduces life expectancy for individuals. People who are obese also spend significantly less time living a healthy life free of chronic disease compared to those of normal weight.” The study found that there is a significant impact of excess weight on life expectancy, and the more severe the obesity, the greater the impact. Being overweight (BMI over 25 and less than 30) can reduce people’s life expectancy by 0 to 3 years, being obese (BMI over 30 and less than 35) can reduce life expectancy by 1 to 6 years, and severe obesity (BMI greater than or equal to 35) can reduce life expectancy by up to about 8 years. The study also showed that the impact of excess weight on life expectancy is age-related: it has the greatest impact on young people aged 20 to 29, while the reduction in life expectancy is relatively insignificant if obesity is present in older age. At the same time, the researchers also paid special attention to the impact of obesity on the “healthy life-years” (healthy life-years, referring to the time to live a healthy life without chronic diseases). The analysis found that the loss of healthy life-years caused by obesity is also very alarming. Among young and middle-aged people aged 20 to 39, severe obesity can even reduce people’s expected healthy life-years by nearly 20 years. ”This study clearly illustrates that the more obese a person is, the younger the age at which obesity occurs, and the more serious the negative impact on his health.” Grover said. “These calculations have clinical use in that they can help obese people and medical professionals better understand how serious the obesity problem is, and they can also visualize the benefits that can be derived from improved lifestyles.” Severely obese friends can’t lose weight with exercise because it causes damage to weight-bearing joints to the point where they can’t even participate in outdoor sports. Sometimes clothes have to be tailored because regular size clothes won’t fit. Many patients inquire when they are hospitalized if there is a single room because they are afraid that their snoring will affect others. At the same time, obesity may cause diabetes, coronary heart disease, hyperlipidemia and other metabolic diseases requiring dietary modifications, and even the right to enjoy good food will be deprived. Severe obesity not only affects life expectancy, but also affects the quality of life of fat people. Time may be wasted in the hospital to check the body, it is better to take the time to seriously put their weight under control.