Rationalizing weakens the ability to control yourself. If you find yourself rationalizing one more bite, two then three... take a step back.
Your body is amazing! If you listen carefully it will let you know when you are done, when it has had all it needs. Even your esophagus will tell you.... even beg you, "PLEASE, don't put anything else down me!" Your taste buds become must less sensitive! Your stomach will send you signals. "No more!" These are your guides. Trust them. They are designed and built to do a specific job... let them do it! Most of the these signs are polite & can go unrecognized, especially if they have been ignored. As you listen, you could possibly be eating 1/2 or even 2/3 less than you are use to.
Use food as fuel. While I was in Japan, we walked everywhere! It was the first time I remember eating in order to support my stamina. Eat to live... not live to eat. Food is meant to be enjoyed; but only within the "hunger or re-fueling" context.
I believe our hearts are pricked by the desire to do better in our health for a reason. This is not about vanity. We were made to desire optimum health. Our health affects every single aspect of our lives. Think about it.
Empower yourself. Serve yourself smaller portions, listen to your body signals, trust them and obey them by putting down the fork. In that moment your self-confidence will shoot through the roof perpetuating even a greater desire to continue to move forward and reach your goal(s).
The desire for better health will soon surpass the desire for more food than what your mind not your body wants.