I'm going to let you in on a secret: I do not care that you are eating a donut for breakfast. The girl next to me does not care that you are eating a donut for breakfast. Neither of us noticed that you were even eating a donut. What's more, is that we care even less that you are having said donut because you've been "so good" all week and ate salad for dinner. There are things worth bragging about, maybe even worth feeling superior about, but your perfect week at the gym is not one of them.
Consider asking yourself this before outwardly justifying your dessert: Why do I feel a need to validate my food? I can tell you this much, the answer is not that anyone else in the room is judging you for it. 99 percent of the time everyone else is too immersed in their own lives to notice such trite things about your meal, and the other 1 percent of the time that judging person has their own issues causing them to judge you.
So really, ask yourself why you feel so judged, because the reality is that the judgement is coming from an inward source. Of course, that inward source has probably been influenced by the taunts of today's media boasting willpower through restrictive diets and intense workouts. They want you to believe this is the ultimate truth and cleansing action so they can sell their product, and much of the time they succeed in planting an intrusive little voice in your head that judges "good" vs "bad" on their terms.
We tend to be our own worst enemies, which makes sense since we are the only ones privy to 110 percent of our thoughts and actions. But it isn't necessary. There is no reason for you to feel any guilt over providing your body with energy, and even less of a reason for you to have to justify that with any other words besides "I wanted it."
You don't have to have gone to a 2 hour cross fit class to "earn" a pastry, don't have to limit yourself to only green vegetables to "deserve" an ice cream cone. No one else thinks any less of you for these choices, and you shouldn't think less of yourself either.
That donut for breakfast is a beautiful thing signifying a freedom of choice and an ability to be self-sufficient, so shut up and enjoy it.