If I just eat veggies fruit nuts and water will I loose weight?

Be better if you cut the fruit.

Nuts are iffy.

Vegetables are, basically, the bees-f******-knees.

4 liters of water AT LEAST.

Lentils are awesome but disgusting (cook 'em till mushy and slow cook in tomato sauce and veg)

Basically yes, be sure to eat varied though(so root-vegetables, starchy-veg, legumes, and beans, Lentils(if you could only eat 1 vegetable, these are perfect) but also tomatoes, peppers, cucumber, and so on). Not just salads, but also vegetable-stews.

For your metabolism to work you need to eat at a balance(50 carbs, 25 protein, 25 fat).

A rocking breakfast is Lentils(just get a small-can(pre-prepared), wash 'em off), quick flash-fry, 2-3 eggs(slightly beaten), poored over, make it an omelet. With a handfull of rocket/arugula, a little olive-oil, and a squeeze of lemon on top.

It's spicy, warm, and easy to digest.

Another tip would be to just use a bag of Soup-Vegetables in an omelet the same way, it really adds to the dish, plus it raises the nutritional values.