NEW ORLEANS — In a patient with a body mass index of 40 kg/m
In fact, said Dr. Nana Gletsu Miller, measuring waist circumference in such individuals is difficult, impractical, and does not provide a good measure of intra-abdominal fat stores, which is the fat that is more detrimental to health.
Dr. Gletsu Miller, of Emory University, Atlanta, showed measuring sagittal abdominal diameter while patients were in a supine position provided information that was more predictive of changes in insulin resistance and other cardiometabolic risk factors during weight loss than did waist circumference measured when the patient was standing up.
The 30 severely obese female patients were assessed at baseline, 1 month, and 6 months after Roux-en-Y gastric bypass or adjustable banding surgery for weight loss. Fifteen of the women also were assessed at 24 months postsurgery.
Visceral and subcutaneous adipose tissue volumes were determined using computed tomography. The height of the abdominal region was measured with a sliding-beam caliper, and waist circumference was measured at the iliac crest with a tape measure.
Other measures included hepatic insulin sensitivity, which was determined using the homeostatic model assessment of insulin resistance index that measures fasting glucose and insulin concentrations, along with the following indicators of cardiometabolic risk: systolic blood pressure, fasting LDL cholesterol, triglycerides, and high-sensitivity C-reactive protein.
All of the subjects exhibited significant decreases in general and abdominal adiposity, sagittal abdominal diameter, waist circumference, and visceral and subcutaneous fat volumes. They also improved measures of cardiometabolic risk, Dr. Gletsu Miller said.
However, as the severely obese subjects experienced weight loss over 6 months, changes in saggital abdominal diameter accounted for 15% of the changes in intra-abdominal fat volumes, whereas changes in waist circumference did not significantly explain these changes, she said.
Dr. Gletsu Miller said more studies need to be done to determine a cutoff value that will best predict insulin resistance and other risk factors in severely obese patients.