I totally thought I came up with the term “gateway bite”, but Mark Sisson has a great article on gateway foods:
True gateway foods can wreak havoc with more than just your intended portion size, however. Suddenly, other things start looking good that you’ve had no taste for in a long time. This particular surrender to temptation can become a catalyst for a broader descent like a gateway drug leading you to something bigger and badder. You’re one brownie away from inhaling half the dessert buffet.
I’ve written about this issue before. The trick is not letting one bite ruin your entire day.