Ever since what started? If you mean something like a depressive episode, than this could certainly be related to that, but the short answer to your original question -- is this a problem? -- is yes.

Yes, it's a problem, because you need to be able to eat a normal amount in order to function. Yes, because you need adequate fuel. Yes, because it sounds as though you've definitely got a disordered eating pattern going.

And, most importantly, yes -- because if it's worrying you enough to post about it, then it's a problem for you.

Do you know what triggered this in the first place? Can you identify any of the thoughts or feelings that you experience when you sit down in front of food?