[ryall]

I often wonder why GP's don't refer patients to fitness/nutrition specialists like they do for everything else.

Medical training does not cover nutrition in any depth, I'd say your average doctor is under-qualified in addition to time poor.

[nradov]

In some countries they actually do give such referrals. But it's rare in the US because most insurance plans don't cover such treatments. That is starting to change to a limited extent; my retired father receives a discount on his medical insurance for going to the gym every week.