Atkins diet is based on keeping a low glycemic index or low insulin levels. Insulin is responsible for promoting storage of injested food. Insulin is stimulated by eating food with carbohydrates.
Although Atkins recommends that you avoid eating carbohydrates at all. The worst thing one person can do is eat their large dinner and a dessert - because the sugar from the dessert will promote storage of most of all the food, including the dinner.
So why not stagger eating -- Eat a large dinner and then only eat dessert after the dinner has been digested ---about 3 hours later.
That way instead of promoting storage of your entire dinner you only store the small dessert you eat and not the entire dinner and dessert.