How many cups are you feeding him? I'm wondering how accurately you are measuring his food. I use a kitchen measuring cup to be accurate. You could reduce his food by 1/4 cup, and add a measured 1/4 cup of boiling water to his kibble to bulk it up without adding more calories. It takes less than a minute for it to be at a safe and comfortable temperature for feeding. Up his exercise as well.
I'm feeding 4 cups of Royal Canin Veterinary Diet Canin Veterinary Sensitivity Control Dry Dog Food. My dog gets fed once a day. He gets training treats and a few shared bites of my food, and a 'roo tendon before bed.