Then add up the calories his / her food provides and never let treats
exceed daily caloric needs.
His particular take on fat intake is a bit more extreme than yours (he consumes 70 % of calories from fat), but he does agree that one should not
exceed daily caloric needs while doing this.
However, if having whey before bed causes you to
exceed your daily caloric needs, you may experience unwanted weight gain.
They aren't going to hinder your fat loss unless you are eating an excess amount of them and
exceeding your daily caloric needs.