Mechanism of Growth Hormone Effects on Adipose Tissue

Growth hormone treatment in humans has been shown to decrease body fat. This study aims to determine what adipose tissue depots are affected by GH and what is the mechanism.

Growth hormone (GH) replacement in GH deficient adults results in an improvement in metabolic status, an increase in lean body mass and a reduction in visceral adiposity. GH might also decrease visceral adiposity in obese adults that are not GH deficient.

The objective of the study is to determine the effects of GH on the metabolic syndrome and visceral adiposity in men with low blood levels of IGF-1 and the durability of these effects after stopping GH therapy. We will use a double blind, placebo controlled 6 month intervention trial followed by a blinded follow-up period of 6 months. Thirty non-diabetic middle aged men with central adiposity (BMI > 27 kg/m2, waist circumference > 102 cm) will participate.

Inclusion Criteria:

• Male, aged 40-70
• Central obesity defined as waist circumference greater than 102 cm and BMI > 27 and < 35 kg/m2
• No weight loss in last 12 months
• Total IGF-1 level < 241 ng/ml (~25th percentile for the assay)
• Body habitus which permitted accurate CT scan acquisition and analysis.

Exclusion Criteria:

• Significant neurologic, metabolic, endocrine, cardiac, respiratory or gastrointestinal disease
• Diabetes
• Known coronary heart disease
• Exercised more than 3 hours per week
• Unwilling or unable to abstain from alcohol for 72 hours prior to the measurements of energy expenditure and fasting blood work