1 jul 1997 año - Obesity classes
added to BMI
Descripción:
 "In 1997, the International Obesity Task Force expanded the number of BMI categories to include different degrees of obesity and changed the terminology modestly.36 A BMI of 25 to 29.9 is referred as “preobesity,” a BMI of 30 to 34.9 is class I obesity, 34.9 to 39.9 is class II obesity, and a BMI of 40 or greater is class III obesity.37,38"
Source: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4890841/ 
Añadido al timeline:
fecha:
1 jul 1997 año
Ahora mismo
 ~ 28 years ago