I prefer the path of least effort when it comes to either putting on or removing weight.
Consider this:
Do you need big breakfasts and then nothing till dinner?
Can you eat a truck load of carbs and still be hungry in five minutes?
Or will a plate of eggs and bacon set you up for six hours?
Once you know how fast your metabolism is running, and what your food is actually doing, you can set about with a plan that will work.
If you were to stop exercising - going to gym, running, sailing etc, would you become heavier/fatter or would your bodyweight stay more or less the same over a period of say, 6 months. How fast would any new weight be put on?
If your body weight would be the same, you needn't change diet, just increase exercise.
If your body wieght creeps steady up, you need to look at less of the same foods, plus a bit more exercise.
Pretty simple approach really.
You should note that caffeine really stuffs up your natural metabolism too. In this case it will assist in you losing weight, but it may come at the cost of not being able to put together an accurate picture of which type of food is best suited to your metabolism i.e. protein, carb, fat. So long term maintenance of any given weight may be more difficult.
It's a big subject. I wouldn't recommend a huge change in diet just because lettuce looks healthy. (although I am clealy not a dietician, or doctor and everything I say should be treated as debateable.

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If you shock your body too much it may eventually swing back to it's original state over the long term, or you'll open yourself up to related complaints, diseases and psychological problems. Body shocks are not nice. Be nice to your body. It's the only one you have.