It is fine to borrow for living expenses as you begin to practice medicine, as long as you do it as part of your business plan, and then you stick to your plan. 

SNB asks physicians who are starting a new practice to develop a business plan that includes financial projections - revenue & expenses.  Your SNB advisor can help you develop this business plan.  You should include your minimum salary requirements -- enough to cover your living expenses -- in your business plan. 

So to borrow for living expenses, make sure you include personal (household) expenses in your business plan and a salary adequate to cover them.  The money you need to fund living expenses becomes part of the loan you will secure to startup your practice.