I don't think you need to feel too guilty about eating out once in a while while on a diet.

In the past, I thought that if I ate out while on a diet, I had ruined my meal for the day.

So, on days when I ate a lot for lunch, I would sometimes skip dinner, but that often resulted in me getting hungry late at night, which messed up my eating rhythm until the next day.

These days, if I eat more than usual for one meal, I just try to go back to my normal amount starting from the next.

It seems like returning to your usual diet is a much more realistic approach than eating the exact same thing perfectly every day.

If you want to maintain a diet for a long time, I think it is necessary to change your mindset starting from these small details.