I love to think that a Human body is a "machine" (yeah I'm an Engineer and it helps ^^)
I have loose A LOT of weight last year (about 17Kg) by doing things correctly. And I keep things in scale since then.
First you have discern weight and fitness.
If you want to be "lighter" you will have to reduce your calories ingestion. If you want to be fit you will have to make sport
These things are NOT related. The only link that could be made is that if you make some sport you will increase your amount of needed calories/day and so, if you keep a fixed amount of calories you will loose weight faster than without sport.
In order to calculate how many calories you need in order to keep your weight go there: http://caloriecount.about.com/cc/calories-goal.php
Fill the fields and get your calorie's need per day in order to keep your weight. (goal-actual weight should be the same)
Then simply buy a food weighting machine (1g definition) and weight ALL what you are actually eating for one week. Don't cheat, simply look how much calories you currently eat in comparison with what you should.
This has two goals:
-first letting you know how much calories are hidden in some aliments. Your brain will love it ^^ In most of the case, just to know how much calorie are hidden in aliments will helps you to not have the desire to eat them. I know it looks strange but it works.
-letting you find some things you like that you can eat in limitless quantities and others that you won't eat anymore because they simply don't taste as good as they bring you calories. (for me it was carrot salad ^^ seems stupid, but I loved it and I could eat as much as I wanted because of the loooooow calories on the other side was some cheese)
Then If you want to reduce or increase your weight, change the "target weight" and it will give you the amount you should eat in order to reach this weight. If you ingest the right amount of calories you will be on target at the due-date. IT WORKS.
That's so simple
Don't trust your brain, trust numbers... If you do it, it will works
. That's as simple and true as reality
Also don't be afraid of the weighting thing. You will actually do it at the beginning because you have to learn a lot of things but after two or three weeks, you just have to look on the packet, and you go.
You will hear a lot of myth concerning diet. We are all different, that's true, but trust me, except in case of a few sickness, if you decrease the calories you eat, you will lose weight and this nearly absolutely linearly.
A few hints:
The biggest problem we have today is that we eat too much carbonhydrates. Why are they "bad"? Because they give you a huge amount of sugar which means a hudge amount of calories. Reduce it and things will go smooth. The fact that you will eat less carbohydrate will also allow you to eat more vegetable and more meat, this will increase your vitamins and proteins amount which result in "fitness" and more muscle build as well as not having the "starving" effect.
Concerning sport. Actually the best sport to lose weight is running. It burns A LOT of calories in a very short time. Try to make some "cardio-training" about 3 times a week and you will immediately see the results. (3 weeks) Cardio training are really easy (about 65% of your max pulse), will make you really fit and only needs one hour
Drink a lot! If you are targeting some weight loss you will have to evacuate a lot of things, drinking a lot is the best way to do it!
And finally, the best advice ever, give you a cheat day per week. This is really important, most of diets failed because people's motivation fluctuate. Be strong with yourself, allow you one REAL cheat day, and hold your diet.
Hope it helps .) And if you have any questions feel free to ask
I learned all from others and I would be pleased to forward it to others also