Most doctors are not scientists and receive next to no training for assessing patients holistically. They are taught next to nothing about nutrition. Most of the trainee medics I met at university admitted that they struggled to pass their biochemistry modules second time around.
Most doctors are more akin to lawyers than scientists. The treatment regimes they advocate are based on precedent as dictated by the pharmaceutical industry. Most are too scared to step outside that comfort zone.
F 5 ft 3. HW: 196 lbs. Primal SW (May 2011): 182 lbs (42% BF)... W June '12: 160 lbs (29% BF) (UK size 12, US size 8). GW: ~24% BF - have ditched the scales til I fit into a pair of UK size 10 bootcut jeans. Currently aligning towards 'The Perfect Health Diet' having swapped some fat for potatoes.