Ultimately no. But it can.

Just having a couple of meals that are typically seen as “bad” foods at the weekend doesn’t automatically mean that you’ll ruin your week of dieting.
But when these meals turn out to be things like a full takeaway pizza with a tub of Ben and Jerry’s you could easily eat enough calories to take yourself out of your weekly calorie deficit.

For example if you maintain your weight at 14,000kcal per week and try to diet with a 500kcal per day deficit (3500kcal per week)
It’s easy enough to eat 3500kcal of pizza and ice cream. Throw in a few drinks the night before and you could find yourself spinning your wheels.

Take home from this post?
Don’t be scared of “bad” foods, they tend to be tasty af.
Just be wise to the amount of these bad foods you eat.