Ten pounds is hardly anything, less than 5 kg, doesn't make much of a difference.
However, are they 10 pounds overweight because of a recent change in their life? Are they on medication? Is the weight gain related to a recently developed medical condition? Or did they turn into a slob that sits on their ass all day and have rapidly started packing on the pounds?
The reason behind being overweight matters. If they don't give a shit about what garbage they're putting in their body, then I wouldn't date them because they will only get worse as time goes by and I don't plan on being anyone's fat sitter.