The answer to your question will depend upon 1) whether you are an exempt or non-exempt employee and 2) your company's policy on breaks and lunches.  If you are an exempt employee, there isn't an issue as your paid a salary regardless of the number of hours you work.  If you are a non-exempt employee, your company's policy will dictate whether lunches are compensatory.  Depending upon how long you work each day, you should be allowed breaks.  If you aren't, talk to your supervisor and/or Human Resources Department.