Participants in a caloric restriction study were selected with a BMI range of 22 to 27.9 to avoid potential safety issues like low bone mineral density or menstrual cycle problems associated with starting at a lower BMI.

“the study to go from 22 to 27.9 of BMI for admission means you know normal weight on the upper range yeah mostly normal weight you know on the plus or minus side of normal weight up to 27.9 and you know it was we we know that we knew that they were going to lose at least 10% and therefore you cannot take somebody with a BMI of 20 to start with you would have problems with bone mineral density you may have problems with some safety men and women or just men men and women right so the other thing you're going to have you're going to have problems with menstrual cycle and things like that”