The two day diet

So I have been doing this diet since last fall.  I use the word "doing" loosely.  Last fall I did the diet for a month and lost 6 pounds.  Then I went off of it for Thanksgiving through New Years and gained 4 pounds.  Then I half-assed it and lost 5 pounds.  Then I gained two, lost two and gained one.  Maybe I am just gaining and losing water at this point.  Anyway, I have been trying like hell to get back on it.  But every day I end up telling myself tomorrow is a new day.  I can always start over tomorrow.  I never make it past day 2.  No wonder it isn't working.  I usually make it through day 2, cheat on day 3 and start over on day 1.  Sometimes I cheat for two days.  Nothing magical happens in 2 days.  It isn't really a 2 day diet.  You don't suddenly drop a bunch of weight in 2 days, you just end up really hungry.  I wake up starving and then cave when I get to the office, eating a chocolate croissant and drinking a chai latte.  I am trying to decide whether to continue.  I am thin already but I have gained weight.  I want to get back to the weight I was a couple of years ago because I just can't get rid of the pants that don't fit.