Get an automatic feeder.

We have an overeater, and a self-limiter. When the overeater developed markers of being pre-diabetic, we finally hardened our hearts and put him on a strict diet. For us, this was extremely hard, as he begged 24/7. He would yowl at all hours of the day, and it woke us up at night. After a month of this with no sign of him changing his behavior, I bought an automatic feeder from Amazon for ~$30.

The main change was that our's quickly stopped seeing us as the main source of food, and this eliminated most of - and all of - the nighttime begging. It took a week or so, but it was pretty fast.

Second, most have multiple feeding times. This helps in two ways: first, it allows more, smaller portions, which eliminates the binge/purge issue. Second, it allowed us to have feeding times throughout the night, which helped with stopping the nighttime begging.

Third, it's really easy to calculate caloric input from just the information on the food bag; the portion sizes can be set in the feeder, and it's an easy, reliable control.

As a minor benefit, it makes feeding easier.

This obviously only works if you feed kibble.

One issue we did have was that we initially gave the self-limiter free-choice kibble on the counter, and it was enough to keep him away from the feeder. This worked because our diet boy was too fat to jump up onto the counters. However, the feeder was so successful that one day he discovered that he had slimmed down enough to get onto the counter, and we had to change tactics. After much tribulation, we simply ended up getting a second auto-feeder and set them to the same schedule. It isn't perfect, but the dieter is still slowly losing weight, and the self-limiter is maintaining, so it seems to be working for now.