Yeah, I was the fat kid in class.

Ok, it's true, I was the fat kid in elementary school. Thankfully, I was also the athletic kid so I could kick anyone's ass who said anything to me about it (and then sit on them to prove my point). I was put on a diet as a child in order to (obviously) save my health. I simply cut back the amount of food I was eating and what I was eating and lost 20 pounds.

The point of all this? Fad diets, shmad diets.

If you want to lose (or gain) weight, it takes two things; determination and consistency.

1) Make a plan
~If you are trying to simply lost weight you need to do cardio plain and simple. Start out with 30 minutes, 4 times a week. Eat fruits, veggies and proteins more than anything else. Don't cut your carbs too much or you won't have any energy. Do not eat sugar. Work your way up to 6 days of cardio a week for 45 minutes or somewhere in between to your own satisfaction. You can also lift wieghts (don't worry, you won't get "beefy" do light weights for 15-20 reps to harden up whatever area you want hardened.
~If you want to gain weight, lift weights. Do not do cardio. You burn enough calories lifting weights to keep your body lean and any extra exercise will only make you skinnier and negate the lifting. Eat lots of protein and lots of carbs (as long as they are good carbs, potatos, pasta, whole grains, rice etc...)
2) Stick to your plan
~Schedule your work out time in advance and keep that time. If you simply go with the flow of your day and work out if you can, you won't do it.
3) Eat right
~ Fruits and veggies are the best thing for you. load them on your plate. If you aren't working out, don't eat a lot of complex carbohydrates, but you can maintain your body wieght just by watching what you eat.
4) Get an accountability partner
~It's a lot more fun to work out with someone else. This person can also kick you in the butt if you start slacking off.

Again, don't fad diet. You will most likely lose water weight and gain it back as soon as your diet phase is over. It is better to make a lifestyle change then try something for a little while.

There is my diet soap box. Hope it was informative.