Defining Obesity, Its Prevalence and Its Causes

Jennifer, known as The Obesity Physio, starts with the WHO definition and the BMI cut-offs of 25 and 30. BMI is a surrogate for fat, ignores where fat sits and misclassifies muscular athletes, so it works better for populations than individuals, yet it still blocks access to treatments such as joint replacement in the NHS. The Lancet Diabetes and Endocrinology Commission now adds excess adiposity and organ or daily-living impact, separating preclinical from clinical obesity. Prevalence at BMI 30 or above was about 10% or less in most regions in 1975 and has risen everywhere since. The 2007 Foresight Report maps how food production, consumption, psychology and physical activity factors such as walkability and motorized transport interact, so the problem is not simply eat less, move more. Weight is a dependent variable, changed only through behavior. She explains Giles Yeo's view of susceptible genes meeting a permissive environment, rare monogenic obesity such as leptin deficiency, and common polygenic obesity involving over a thousand genes.