Dietary Supplements, Nutrition

I am 5' 3" and 110 lbs and I really need to lose weight (i know it doesn't sound fat but if you see me i really am....its weird). I am going on this diet will it work:

Breakfast:
1 small egg white omlette (20 calories)
1/2 a grapefruit (30 calories)

Lunch
1/1 a grapefruit (30 calories)
1 nutritious salad (10 calories)

Dinner
tuna fish (40 calories)
fruit e.g. strawberry, peach etc (40 calories)
fat-free yogurt (30 calories)

That's a total of 200 calories and I do 100 sit-ups, 200 leg raises before going to bed.

Will this diet work? How long do I have to stick to this diet in order to lose 10 lbs. Thanks.