He nibbled and nibbled, and panted, but still, he kept gulping it down till he made himself ill; Yet he swallowed it all, and 'tis easy to guess, he was soon so unwell that he groaned with distress.
The negative form of the imperative has don't in front of it, like this: Make sure you have a balanced diet - don't overeat and don't eat the wrong foods.
In the hot summer light his floridness seemed heavy and bloated, and but for his erect square-shouldered walk he would have looked like an over-fed and over-dressed old man.