5lbs underweight is better than 5lbs underweight 10lbs overweight is better than 10lbs underweight depending on how much muslce you have too. 15lbs overweight could be better than 15lbs under anything over 20lbs for both is probably bad either way 30lbs overweight is worse than 5lbs underweight. being a few pounds underweight, is better than being overweight, but a few pounds overweight is better than being alot overweight.
Both have + and - , but better to be underweight , because overweight are making more problems ( heart , hemoglobin ... ) , but underweight make your bones not so strong as they are when you are overweight a little .
Over weight.If you are too skinny then you may be too weak and that would mean you are more prone to diseases..because your immune system would be weak.But being over weight also leads to many severe diseases.ONly difference is you would get different diseases if you are underweight and different ones for overweight.So it's better to be fit.