A lot of data from a credible source says being mildly overweight might be OK.

JAMA abstract (full text costs $): "Overweight was associated with significantly decreased mortality from noncancer, non-CVD causes...but not associated with cancer or CVD mortality."

David Usborne from The Independent UK, elaborating: "Those Americans who were merely overweight were up to about 40 per cent less likely than normal-weight people to die from a whole range of diseases and risks including emphysema, pneumonia, Alzheimer's, injuries and various infections."