I make healthy food choices.

The choice mostly gets made in the shop, not at the table. What you eat at nine at night was largely decided on Saturday by whoever was pushing the trolley.

Willpower at the fridge door is a losing position — you're tired, it's late, and some part of you decided hours ago. Willpower in aisle four is far cheaper, because you're not hungry yet and nothing is at stake.

Move the decision upstream and it stops being a fight every evening. You just end up eating whatever is there.