Peptides are everywhere right now: weight loss, skin care, muscle recovery, tanning. We got the President of the Australian Medical Association Dr Danielle McMullen on the phone to explain what they actually are and why the ones being sold online are a problem. Short version: the approved ones prescribed by doctors are fine, but the unregulated ones sold online may have never been tested on humans, can cause cancer, blindness or kidney damage, and often say not for human use right next to the injection instructions. Also it turned out she used to be Tim's GP which raised more questions than it answered.