I have read alot of articles and research that state, diet chemicals actually make you gain weight by causing you to crave carbs and sugar.  The most common of these are asparteme and sucralose (splenda, sweet&low, equal).   Their is also information out there that states these chemicals are poisen to the body.   Their is a great online presentation that shows the history of how these chemicals were even approved by the FDA.   They were originally rejected because they caused cancer in test mice, but after a change in FDA leadershipm lobbying and backdoor payoffs they became FDA approved.  Poisen aside, I recently felt the affect of splenda cravings first hand.

I used to be a huge soda drinker and I hated diet anything, I couldn't stand the taste.   When I first decided to lose weight I switched to diet.   One of the reasons I yoyo was I always had powerful cravings for carbs, cake sweets.   I would resist for a while and then when I decided to have "a cheat day" I would completely bing.   As time has gone on I have eliminated my intake of these chemicals.  I drink almost exclusively water.   Once in a while I do like a soda with a meal but I won't drink the whole thing.   The most important change was instead of two splendas in my coffee every morning I switched to two stevia natural sweetners.   I also use xylotol a natural sugar alchohol, and sometimes agave nector.   I really didn't notice the change in how I felt until yesterday.   I had a healthy lunch and then, I had to go to a business meeting.  My associates wanted to get something to eat so we went to Ihop.  they order a burger, steak omeolette, pancakes.   I was completely, fine no cravings.  All I had was a coffe (with the unlimited caraffe).  The meeting was 45 minutes and while we talked and they ate I had about 4 cups of coffee, two splendas in each.   When I went home that night I was starving, hungry like I hadn't felt in a long time.  I ate a low carb dinner and it didn't satisfie me.  I had an uncontrollable urge for carbs, sweets, food that I hadn't had in along time.  I wound up eating some immitation crab meat and that didn't satisfie me,,,then I had a fiber one cookie, but I still wanted more.  It was the first time I really noticed the change in how I was feeling before and I I used to feel all the time.  I asked myself what changed, what did I do different today that I haven't been doing?  The difference was I had 6 splendas.   If you think that sounds like alot, do you put splenda or equal in your coffee?  Do you then have a diet soda at some point?  How many?   Are you having uncontrollable cravings, and also having 6 low calorie sweetners a day?  Maybe that is what is sabotaging you, it was for me.   Try detoxing from it and see what happens.   If you must have something sweet, stick to real sugar, just try to limit your intake.