HEALTHY SUBJECTS

1. 40 healthy subjects, 20 male, 20 female, ages 18-45 yr.: (i) 20 (10 male, 10 female) who are overweight/Class 1 Obese (BMI 25-34.9) with abdominal fat accumulation (central adiposity) defined by waist circumference (WC) ≥ 102 cm in men, ≥ 88 cm in women, except in East/South Asians for whom the criteria will be WC ≥ 90 men and ≥ 80 women; (ii) 20 (10 male,10 female) who are lean (BMI 19-24.9) and not meeting these WC criteria.

2. No medical conditions except being overweight/obese in half of subjects

3. No prescription medication or other drug use

4. On screening testing: BP<140/<90 mmHg, HbA1c<5.7%, FPG<100 mg/dL, normal IGF-1 and TSH levels.

5. Premenopausal women: use of nonhormonal method of contraception

6. Current non-smoker

GH DEFICIENT SUBJECTS

1. 24 patients with isolated GH deficiency:12 males, 12 females.

2. Ages 18-45 years

3. Diagnosis of isolated GH deficiency based on accepted, BMI-appropriate GH stimulation test cut offs within 12 months of enrollment

4. No prior GH therapy within 12 months of study enrollment

5. Normal thyroid, adrenal and gonadal function documented by accepted stimulation test and clinical criteria

6. Premenopausal women: use of nonhormonal method of contraception

HEALTHY SUBJECTS

1. History of malignancy, diabetes, thyroid cancer or pancreatitis

2. Recent dieting, weight change >5%, pregnancy or lactation or heavy exercise

3. Use of glucocorticoids, hormonal supplements or medications that could affect GH or IGF-1 or for weight loss within 6 months of enrollment

GH DEFICIENT SUBJECTS

1. DM requiring medication

2. HbA1C > 7.5

3. Malignancy, pancreatitis or thyroid cancer history.

4. Deficiency of other pituitary hormones, liver or renal disease

5. Use of glucocorticoids, hormonal supplements or medications that could affect GH or IGF-1 or for weight loss within 6 months of enrollment

5. Recent dieting, weight change > 5%, pregnancy, lactation or heavy exercise 6. Current smoking