The best regimen comprises what you can and will actually do sustainably. This applies to education, exercise, and diet.

My diet currently consists of 3 rules:

1. Only eat when hungry, rather than when strongly emotional or when encountering free food (in, say, the office microkitchen).

2. Eat with time and attention, instead of shoving food down my gullet while multitasking on my phone.

3. Avoid sugar, though don't expect to completely remove it.

Note the simplicity; simplicity promotes reliability.