Max is 1.5 yrs old and weighs about 28 lbs. He gets two meals a day and walks about 3 kms everyday. The trick in making out whether they are overweight is from above, their waistline should be distinct from their stomach and a hint of ribs seen from the side. Agree, they are absolute masters in the sad you-are starving-me look. But be firm, its for their own good.
A sure way to get the weight off is to cut back on how much food you give them. After you get the weight off you can gradually increase how much you feed them until you see the weight coming back. That's the point where you have gone past the equilibrium. Back off from that a little bit and you should be good.