When our country won the Revolutionary War, we set boundaries to mark our new territory. We did that to minimize future conflict and preserve the health of our nation.
In the same way, to win the war on weight control, you must set boundaries regarding how you expend your time and energy. Otherwise, you might feel inordinately stressed, and your stress could lead you to stress-eat and become unhealthy in other ways.
In my case, during the work day, if I don't minimize unnecessary conversation with patients, I get behind, and getting behind stresses me out. The problem arises when I get a very needy, lonely, or exceptionally anxious patient, or a patient who is very interesting or is a talker like me. I tend to stay in the exam room an unfairly long time with those patients, if I'm not careful. The anxious patients tend to ask a bazillion questions (this is how they attempt to feel less "out of control" in the midst of their anxiety). But no matter how many questions I answer, their anxiety leads them to ask more and more questions.
I hate having to handle things this way, but sometimes I have to literally cut the anxious or overly talkative patients off, mid-sentence. I look at my watch and apologetically (but very bluntly) say, "I have to go. I have other patients waiting. Maybe you could write your remaining questions down so I can answer them next time."
Though you sincerely may want to help and serve others because you have a good heart, it's okay to turn people down, cut them off (politely), tell them you have to go, etc., in certain situations. If you don't, you might pay for it later through your own physical, stress-induced illness or other unwanted and unhealthy behaviors (like overeating).