Fasting doesn't have to be all-or-none, as you know. It depends on the goal.
Skipping dinner OR breakfast is fasting. Skipping dinner AND breakfast is fasting longer. There's eating "normally" during the week and not eating on the weekends. Or, alternate day fasting. Or, eating all food during a specific window of time -- from 12 hours all the way down to one hour.
There's also the fasting mimicking diet that allows people to ingest some food, but at very low calorie levels. For me, it's easier to go completely without food, rather than having a small calorie intake that just makes me want more food. But, that wasn't always the case. The longest fast I've done is only seven days.
One of our members completed a 35-day water-only fast.https://www.healingwell.com/community/default.aspx?f=30&m=4175117Another went carnivore (not a fast, obviously) and had remarkable improvements.https://www.healingwell.com/community/default.aspx?f=30&m=4110185I think by eating a boring diet, whether it's only steak OR only potatoes (not both!), people naturally eat less. What a person eat determines how much they eat.
The best first step, I believe, is to not eat from the moment we wake until the moment we go to sleep.