One of the most (if not THE most) important qualities in any fitness endeavor is consistency.
In fitness you won’t make significant improvements training one day per week. You need to train consistently for weeks, months, and years to make progress.
In nutrition you can’t make progress by eating healthy 2 days per week, then gorging yourself the other 5 days. It simply won’t work. You need to be consistent with the way you are fueling your body.