Most labs (unless field labs) are bigger anyways. They have a stockier build then most dogs. Your naighbour sounds like he/she knows nothing. If I remember right feeding them raw balances out their weight, they wont get too fat or too skinny if you feed them the right amout.
What are you feeding him now?
That might be the problem too.
And I agree swimming lessons makes them loose weight as a PTer's dog on here dose that and has lost weight.
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