Would studying nutrition be a good use of medical students' time? Within an evidence-based medicine framework, hardly any nutritional studies qualify as "high" quality. Much of it is barely a step above junk with multiple uncontrolled variables. And in fairness to nutrition researchers, limits imposed by funding and ethics make meaningful large-scale human studies very difficult.

https://en.wikipedia.org/wiki/Hierarchy_of_evidence

In terms of human nutrition we know how to prevent acute diseases caused by deficiencies like kwashiorkor, beriberi, scurvy, Rickets, etc. And we know that excess consumption causes weight gain. Beyond those basics we should treat most nutritional claims with skepticism, regardless of whether they come from a physician, dietician, or nutritionist.