First, I must take a sip of water.
Next, I have to eat a serving of vegetables or fruit.
Next, I can eat a serving of nuts or more fruit.
Last, I am allowed whatever terrible yet tasty treat I want, up to one serving.
Not completely accurate. First, the author's reasoning is more interesting than that specific stack. Second, you can opt out at any time: So replace "have to eat [...]" with "may eat".
