This study will determine whether electrical stimulation of an area of the brain called the
dorsolateral prefrontal cortex, which is important in determining the feeling of fullness
after eating, affects how much food a person eats and weight loss over 4 weeks. It will also
compare weight changes in people who attend weight loss counseling sessions and those who do
not over this period of time.
Obese, non-diabetic people between 18 and 60 years of age who are in good health and who live
in the Phoenix, AZ, metropolitan area are eligible for this study. Candidates must have a
body mass index of 35 kg/m(2) or more and weigh less than 350 pounds.
Participants are admitted to the NIH inpatient unit in Phoenix for the first 9 days of the
study for tests, which include meal tests to determine eating behaviors and caloric intake,
blood and urine tests, glucose tolerance test, weight measurement, psychological assessments
and DEXA scan to measure body fat. For 3 of the days, they will be asked to eat all of their
food from automated vending machines. Some subjects receive transcranial direct current
stimulation (TDCS). For this procedure, electrodes that conduct electricity are placed on the
head and arm and the current is turned on for 40 minutes. Some tingling may be felt under the
electrodes. Other subjects receive sham TDCS, with the current turned on only very briefly.
After the evaluations, subjects are discharged home from the NIH unit and instructed to eat
25 percent fewer calories than they consumed while on a weight maintenance diet the first 3
days of their inpatient stay. They maintain the lower calorie diet at home for 4 weeks.
During this period they come to the NIH unit 3 days a week to receive either real or sham