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Healthy obesity? does not exist at all

  Lifestyle is an important confounding factor that significantly affects the relationship between fat content and mortality risk. A few days ago, a study by Professor Li Qifu’s team from the Department of Endocrinology, The First Affiliated Hospital of Chongqing Medical University showed that there are “healthy thin” and “unhealthy thin” for people with low body fat content, but for people with excessive fat content, it is not There is “healthy obesity”, which has important clinical implications for lifestyle-guided improvements in quality of life and life expectancy.
  As the prevalence of obesity increases year by year, the relationship between fat content and mortality risk has attracted much attention. Previous studies have suggested that, relative to normal body weight, having too little or too much fat will increase the risk of death; however, some studies have shown that being overweight or mildly obese does not increase the risk of death, or even reduces the risk of death.
  The relationship between fat content and risk of death is currently inconclusive. Based on the large sample cohort of the UK Biobank, using combined genome-wide association study, polygenic risk score and Mendelian randomization method, Professor Li Qifu’s team revealed the relationship between body fat content and mortality risk. There was a linear causal relationship, showing that an increase of 1 kg per square meter of fat content was associated with an 8% increase in the risk of death. Professor Li Qifu’s team used bioelectrical impedance to measure the fat content to analyze its relationship with the risk of death. The results showed that the fat content and the risk of death were nonlinear, that is, too little or too much fat, and the risk of death increased.
  Mendelian randomization is a new causal relationship analysis method that has emerged in recent years. The analysis results based on this method show a linear causal relationship between fat content and all-cause mortality. After switching to traditional fat content assessment methods, The linear relationship disappeared, further suggesting that traditional methods may be affected by confounding factors. Professor Li Qifu’s team further analyzed and found that lifestyle is an important confounding factor, which seriously affects the relationship between fat content and death risk: in people with a healthy lifestyle, the relationship between fat content and all-cause mortality is linear, that is, the higher the fat content, the more The higher the risk of death, the higher the risk of death, and in people with an unhealthy lifestyle, either too much or too little fat increases the risk of death.
  The research results were recently published in the international journal “Metabolism”.