I have been on a diet for a while.why can't I lose weight?!

I have been on a diet for a while.why can't I lose weight?

It don't matter what I do it is so hard for me to lose weight.I'm currently taking diet pills and it seem like I'm begining to lose some weight,But I worry about the side effects.I know that the pills can't be good for you.But its the only thing that will work. Even when I'm not taking pills I don't eat that much. I try to eat foods that are good for you,like Fish,Chicken,Turkey ,Tuna, And lots of fruits and veg.I don't know what else to do except keep taking the diet pills That was my last option.Does any one have any suggestions?

I'm a mechanical engineer & regardless of what gimmicks or programs you use, weight loss is controlled by one thing alone. You need to burn more calories than you intake. This is proven by the the law of conservation of energy, I won't get into that but you can probably find it on wikipedia.

I will give you an example though. If you have a shopping cart that's half full, and every day you add 3 cans of food but take out 4, that cart will eventually empty. The cart is your body, the cans in are calories in food and the cans out are calories spent (Just walking, talking, breathing account for a lot of these, but you can increase them with exercise).

So if your weight is constant now, you can lose weight by exercising a little more & eating fewer calories. This is a gradual loss, but it will happen, the laws of physics prove it. If it isn't happening, then you AREN'T BEING HONEST with yourself on eating and/or exercise. Give this a try & expect to lose a pound or two a week. This doesn't sound like much, but it adds up over 3 to 6 months.

One final thing on eating. You, like me, are probably "Americanized" in that we eat way too much, even if it's a healthy item. A serving of meat should be about the size of a deck of cards, not the size of a dictionary.

Good luck!!

NOTE: I want to edit my answer slightly based on the answer below mine. Remember that I say to reduce calories, not stop eating. As stated below, you can accomplish this by eating more of better foods. So if you eliminate junk food & high fat food, you can actually eat more of healthy foods and still lower your caloric intake.