Would you tell me if I need to use a or the before harsh truth in the sentence below.
When you are trying to lose weight, you have to make sacrifices, such as cutting down on or cutting out completely highly processed food. That's just a/the harsh truth.
I've noticed that truth is usually used with the, but I've always come across instances where it's been used with a. Are both possible in the context I provided, if so is there a nuance of difference between a and the there?