Growth Hormone Changes Your Body Composition, Not Your Strength

Growth hormone has a reputation as a muscle builder. People who use it expect to get bigger and stronger, and many of the questions that come up once they start are about the side effects: numb hands at night, swollen ankles, aching joints, rising blood glucose. A 2013 review in Frontiers in Endocrinology by Reed, Merriam and Kargi brings together what is known about growth hormone (GH) in adults: what happens when the body doesn't make enough, what replacement does, where the side effects come from, and what the research shows when healthy people take it. In people who already make normal amounts of GH, one pattern keeps appearing. Extra GH reliably changes body composition. It does not reliably make them stronger.

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1. What GH deficiency looks like

The review starts with adults who don't produce enough GH, usually because of damage to the pituitary or hypothalamus. Their bodies show what GH does by what goes missing.

• Adults with GH deficiency carry about 7% more total body fat than healthy controls, with a similar loss of lean body mass. The extra fat tends to sit centrally, around the waist.
• Muscle mass and strength are both lower. The heart is affected too, with reduced left ventricular mass and lower cardiac output.
• In one study, exercise capacity was 20 to 25% lower than in healthy controls.
• Bone density is reduced, and blood lipids shift the wrong way, with higher triglycerides and lower HDL.