• 24-hour growth hormone secretion [ Time Frame: Measured at baseline ] [ Designated as safety issue: No ]
• GH stimulation peak [ Time Frame: Measured at baseline ] [ Designated as safety issue: No ]
• Body composition and cardiovascular risk markers [ Time Frame: Measured at baseline, 6 weeks, and months 3, 6, 9, and 12 ] [ Designated as safety issue: No ]

• 24 hour growth hormone secretion at baseline
• GH stimulation peak at baseline
• Body composition and cardiovascular risk markers at baseline, 1m, 3m, 6m, 12m.

• Measures of insulin resistance [ Time Frame: Measured at baseline, 6 weeks, and months 3, 6, 9, and 12 ] [ Designated as safety issue: Yes ]
• Insulin-like growth factor-I (IGFI) levels [ Time Frame: Measured at baseline, weeks 3, 6, 9, and months 3, 6, 9, and 12 ] [ Designated as safety issue: Yes ]
• Nutritional status, exercise, weight, waist and hip circumferences, and resting energy expenditure [ Time Frame: Measured at baseline, 6 weeks, and months 3, 6, 9, and 12 ] [ Designated as safety issue: No ]
• Cognitive function [ Time Frame: Measured at baseline, and months 6 and 12 ] [ Designated as safety issue: No ]

• Glucose and insulin levels at baseline, 1m, 3m, 6m, 9m, and 12m
• IGFI levels at baseline, 1m, 2m, 3m, 6m, 9m, and 12m
• Nutritional status, exercise, weight, waist and hip circumferences, resting energy expenditure at baseline 1m, 3m, 6m, 9m, and 12m.

This study will compare growth hormone levels and cardiovascular risk markers in normal weight and overweight women and men. In women and men with increased abdominal weight, growth hormone (GH) versus placebo will be administered and effects on cardiovascular risk, insulin resistance and body composition will be measured.

The purpose of this study is to measure growth hormone levels in women and men who are normal weight, overweight, and obese. Growth hormone levels will be correlated with body weight, body composition, and markers of cardiovascular risk. In overweight or obese women and men with increased visceral adiposity and below average IGF-1 levels, growth hormone versus placebo will be given for 6 months. Effects of growth hormone treatment on weight, body composition, insulin resistance, lipids, and cardiovascular risk markers will then be assessed. Study subjects will be followed for an additional six months for these endpoints.

• Drug: Nutropin AQ growth hormone
  Participants will give themselves injections of growth hormone every night for 6 months.
• Drug: Placebo Growth Hormone
  Participants will give themselves injections of placebo growth hormone every night for 6 months.

• 1: Experimental
  Participants will receive growth hormone replacement therapy.
  Intervention: Drug: Nutropin AQ growth hormone
• 2: Placebo Comparator
  Participants will receive placebo.
  Intervention: Drug: Placebo Growth Hormone

Inclusion Criteria:

• For growth hormone measurement part (for men and women):

  1. For visceral adiposity arm: waist circumference greater than or equal to 88 cm for women or 102 cm for men, and BMI greater than or equal to 25 kg/m2
  2. For lean controls: BMI 18.5 to 24.9 kg/m2

• For growth hormone treatment part (for men and women):

  1. Visceral adiposity (waist circumference greater than or equal to 88 cm for women and 102 for men, BMI greater than or equal to 25 kg/m2)
  2. IGF-I within the lowest 2 quartiles for age and gender
  3. Willingness to maintain current activity level and diet

Exclusion Criteria:

• Diabetes mellitus (fasting plasma glucose greater than 126 mg/dL or 2-hour post-oral glucose tolerance test [OGTT] plasma glucose greater than 200)
• Taking the following medications in the last 3 months: weight loss or lipid-lowering agents, medications to treat diabetes mellitus or "pre-diabetes", oral contraceptives or estrogen-containing medications, other medications known to significantly affect weight
• Smoking
• Hematocrit below the lower limit of normal
• Amenorrhea for 3 months (in women)
• Pregnant or breastfeeding (in women)
• Polycystic ovary syndrome (in women)
• Weight that exceeds 280 pounds
• SGPT greater than 2 times the upper limit of normal
• History of malignancy, except for fully resolved basal cell carcinomas of the skin (Specific Aim 2 only)
• Radiation exposure greater than 1000 mrem over the last 12 months
• Previous diagnosis of cardiovascular disease
• History of pituitary or hypothalamic disease, brain radiation, or childhood growth hormone deficiency
• History of carpal tunnel syndrome that has not been surgically treated