Hello how may I help you? I need some advice. It would be my pleasure to assist I have a St. Bernard. How much dog food should I go through in one week? Do you have a full grown St. Bernard or is he a puppy? He is and older dog. He should be eating approximately 8 to 8.5 lbs of food per week Wow! I have been overfeeding him. No wonder he's getting fat. It is very easy to overfeed. You can also incorporate vegetables in their diet That's a good suggestion. May I help with something else? No thank you.