Why diets fail

Like many of us, I've tried a few diets in my life and failed miserably. I may not seem like I need to lose weight to the regular eye, but there have been times where I felt extra fluffy and just needed to eat BETTER. I don't know the exact statistics on the successes of diets but I'm fairly certain that less than 5% of all diets are actually successful. In dating a physical trainer for nearly 5 years there's one thing I learned (well, there's a lot more I learned but for the sake of time...) diets, for the most part, fail because it is too much of a drastic change for people to accept into their normal routine. You're not just changing eating habits, you're trying to change shopping habits, spending habits and acquired tastes. For someone who eats 8 times a day and doesn't distinguish between something healthy and unhealthy, it will be quite a challenge to go to eating 3 balanced, healthy meals. It makes me cringe when I see people who are used to eating McDonalds every day, go to eating salads. If you don't see the red flag there, you need to make an appointment with a nutritionist as soon as possible. You won't stick to it and you'll end up more upset that you failed yet another diet. (of course there are exceptions to every situation, some people really can do it, and more power to them!) 
In starting to work out again recently, I've also made it a point to adjust my eating habits. I know myself and I know my body. There are certain things I will never be able to change. For instance, no matter what I do, my metabolism burns everything I eat before 9pm and by 10pm I am plain out STARVING. Instead of starting a diet and not eating after 8pm, like I used to think was the right way to go, I simply adjust my late night snack from chips to carrots. 

My point being, diets fail because people take leaps instead of baby steps. Nothing gets accomplished (health wise) if you jump into something you are almost certainly going to quit. Moderation is the biggest key. I love chips. I still eat chips. Except now, instead of eating a small bag and chasing it down with a sprite, I'll eat a handful and drink water or tea. Instead of eating a loaded baked potato, I'll eat a plain baked potato or put just a tad of sour cream. 
I know if I take everything I'm used to away and replace it with things I don't normally like to eat, I'll be unhappy, hungry, and eventually quit the diet all together. 

Just a tip. Moderate rather than throwing yourself into starvation :)