" So even within a “normal” BMI, the risk of developing chronic diseases, such as type 2 diabetes, heart disease, and several types of cancer, starts to rise toward the upper end, starting as low as a BMI of 21. BMIs of 18.5 and 24.5 are both considered within the normal range, but a BMI of 24.5 may be associated with twice the heart disease risk compared to 18.5.397 The ideal BMI appears to be between 20 and 22, confirmed in a study of an “unusually slim cohort” from the Oxford Vegetarian Study.398 "

― Michael Greger , How not to diet