Q: actually why do people spread their meals

A: Eating many small meals throughout the day is best for both losing fat and gaining muscle. Except for brief periods of intense physical activity (such as workouts) your body needs energy steadily throughout the day -- eating many small meals supplies that energy. Otherwise, if you just have 2 or 3 big meals then those meals give a big dose of energy to your body that it has no use for -- the result is that those extra calories go into fat deposits.

Eating small frequent meals keeps your metabolism up. Another analogy is to think of your metabolism as a camp fire. If you throw big logs into the fire every several hours, it won't do it any good. On the other hand if you keep feeding the fire with small branches it will burn strong.

Of course you have to keep in mind that your body is far too complex to be completely explained with simple analogies like that, but the overall theme is still correct: eat small frequent meals to keep your metabolism up, burn fat, and build muscle.