It may depend on the school and their goals.
Showing that you have done well despite economic hardships in childhood does get an adcom's respect.
While it doesnt' require a fatal case of malnutrition, economic disadvantage might be something along the lines of living in government subsidized housing or a homeless shelter, and/or qualifying for free or reduced price school lunch and/or Medicaid (government health care payments for the poor and disabled), working to help support your family while in high school (actually paying household bills, not just spending money for clothes & entertainment). If you were raised by a single parent, and if your parent worked for minimum wage or had health issues that greatly reduced the income available to the household then you might be justified in identifying as "disadvantaged".
These applicants often don't have the advantage of taking MCAT classes, tutors, private music & dance lessons (for well-roundedness), foreign travel, parents & neighbors with connections to shadowing and summer employment in health care settings.