I'm not a medical expert, of course, but I strongly suspect your doctor is concerned about your weight because he knows you're in danger of damaging your health, and even shortening your life.
And I want to assure you that God is also concerned about this. He loves you and wants what's best for you -- and that includes your health. We can't control everything about our health, but we can control some things, and diet is one of them. This is one reason why the Bible commands us to avoid gluttony and overeating. One of the false accusations made against Jesus by His enemies was that He was "a glutton and a drunkard" (Luke 7:34).
You're right when you say good food is a gift from God, and that He wants us to enjoy it. Think how dull our lives would be without it! God didn't have to make food enjoyable, but He did, and it should be constant a reminder of His goodness to us.
But this must never be used as an excuse for abusing our bodies or neglecting our health (as I'm afraid you may be doing). Instead, God wants us to take care of our bodies and use them for His glory. The Bible says, "You are not your own; you were bought at a price. Therefore honor God with your body" (1 Corinthians 6:19-20).
Listen to your doctor and follow his advice for healthy living. Then ask God to help you become "self-controlled, upright, holy and disciplined" (Titus 1:8).