Conditions: Obesity
Allocation: RANDOMIZED | Intervention model: CROSSOVER
Enrollment: 66
Healthy volunteers: yes

Brief summary:
In Protocol #2, we will select 30 obese pubertal and 30 obese prepubertal subjects with an abnormal cytokine profile (i.e. fibrinogen and/or hsCRP concentration greater than or equal to 2 Standard Deviations (SD) above the mean established in our lab for lean controls in Protocol #1). They will be randomly assigned to either lifestyle intervention (diet/exercise) or diet/exercise plus metformin for 6 months. After the 6 month evaluation the subjects will cross over the treatment arms, i.e., those that were doing diet/exercise intervention only will add metformin, those that were doing the diet/exercise plus metformin will discontinue the metformin and continue with diet/exercise changes only. Intrahepatic fat contents will be measured as well.

The investigators hypothesize that obese children in these age groups will have increased cardiovascular risk related to their obese state before reaching the currently defined criteria of metabolic syndrome.

The investigators hypothesize that these cardiovascular risks can be reduced with lifestyle and drug interventions.

Detailed description:

Arms:
arm 1: Diet/Exercise only in first intervention period and Diet/Exercise plus Metformin in second intervention period (no washout period). arm 2: Diet/Exercise plus Metformin in first intervention period and Diet/Exercise only in second intervention period (no washout period).

Interventions: intervention 1: Metformin intervention 2: Dietary modification with caloric restriction intervention 3: Establishment of exercise protocol
Intervention descriptions: intervention 1: Metformin, 250mg by mouth twice a day with meals will be started and if tolerated increased to 500mg twice a day in 3 days in those less than 12 years old and titrated further to 1000mg twice a day if tolerated. intervention 2: The life style intervention changes will include a hypocaloric diet representing at least a 500 kcal/day reduction based on their dietary histories and Resting Energy Expenditure (REE) determined by the initial calorimetry. intervention 3: Participants will attend the Fitness Center 3 times per week and supervised by an exercise technician or exercise specialist. Exercise will be individually prescribed for each participant based on their functional abilities. Exercise will consist of 5-10 minutes for warm up and stretching, followed by 15-30 minutes of cardiovascular exercise (i.e. treadmill, bicycle ergometer, rower, nustep, etc), 10-20 minutes of strength training (supervised using weight stack equipment), and 5-10 minutes of cool down and stretching. As children typically do not need an exercise prescription based on heart rate, we will familiarize them with perceived exertion scales and monitor that they are exercising in the moderate to hard range of perception of effort. Participants will be started at 15 minutes of cardiovascular exercise and 10 minutes of strength training exercise, progressing by 2-3 minutes every week until 30 and 20 minutes is achieved for each respectively.

Protocol document: