Masters are careful about portion sizes. Most of them have learned from long experience to gauge portion size by eye. But if their weight starts creeping up they go back to weighing and measuring portions, especially foods which are higher in calories, such as meat or dairy products. When I'm preparing for photos, as I am at this writing, I weigh or measure portions and write everything down in my training diary. This gives me a handle on how much I'm eating and allows me to adjust my diet as necessary to achieve peak condition.
Masters plan their meals.
Fletcher says many of them plan meals up to a week in advance. I began using this simple technique about 20 years ago. It has saved me from eating many thousands of excess calories. Masters eat consistently. Personally, I never miss a meal.