You are not able to claim a deduction for the cost of food, drink or snacks you consume in the course of your normal working hours, even if you receive a meal allowance. These are private expenses.
You may be able to claim a deduction for meals when you travel for work – see doctor, specialist or other medical professionals' Travel expenses.
You may be able to claim a deduction for meals when you work overtime – see doctor, specialist or other medical professionals' Overtime meal expenses.