Health

do I lose weight just by eating fruits for one month

no!! You need a balance.
fruit is great, but you still need cirtain amount of protiene and fiber and all sorts of things that mainly come in meet, bread etc.

have a look here: http://www.hpathy.com/healthtools/calories-need.asp

and find out what you need to be eating.
exercise, and a balanced diet will do heaps more than just eating only fruit.

jakeins got it right.
plus, fruit can contain a substantial amout of acid which would be so bad for your teeth.

It may help you lose a little weight if you replace all of your snacks with fruits and perhaps have fruits with every meal, but if you want to see significant weight loss, you should try either healthier alternatives at each meal and exercise.