In 2010, there were 78 million adults classified as obese in the United States, and roughly 164,000 primary care doctors to take care of them.

It doesn't take a math wizard to figure out that doctors who handle routine care, although they may well want to help their patients lose weight, are unlikely to have the time to provide the kind of intensive coaching to that would help their patients make a lasting change.

Researchers are studying the ability of beneficial micro-organisms - or probiotics - to treat a range of conditions from eczema to inflammatory bowel disease. And the idea that "good" bacteria are healthy for us is gaining traction.

But the science is tricky.

The letters O-C-D have become a punch line to describe people who make lists or wash their hands a lot. But for some people with obsessive-compulsive disorder, the intrusive thoughts and rituals are severely disabling and don't respond to drugs or behavioral therapies.

So doctors have been trying a new treatment for OCD: deep brain stimulation.

Deep brain stimulation is best known as a way to reduce the tremors of Parkinson's disease. A surgeon places wires deep in the brain that carry electrical impulses from an implanted device a bit like a pacemaker.