Pain sensitivity and obesity.

Endogenous opiates have been implicated as regulators of mood and pain. Recent literature suggests a relationship between these internal opiates and ingestive behaviors in both animals and humans. The present study investigates this relationship by comparing the pain sensitivities of obese and nonobese subjects. Twenty-six subjects (18 females, 8 males) whose weight was 130% or greater of their ideal body weight (IBW) constituted the obese experimental group, while 34 subjects (14 females, 20 males) whose weight was less than 130% IBW formed the nonobese control group. Volunteer subjects were sought from a general medicine clinic of a hospital. Each subject placed his index finger in a pressure device bearing a 3-pound weight and was instructed to report the first occurrence of pain and the desire to remove the finger from the device. Obese subjects were significantly more pain sensitive. The difference in pain sensitivities supports the hypothesis that the weight difference between the obese and nonobese subjects may be related to endogenous opiate control of ingestive behaviors.