Earlier quoted context omitted.
You are mistaken if you think that hunting was the primary source of food in times before agriculture. For many tribes it was (and still is, in some parts of the world) a secondary "luxury" which augmented the gathered food. As you say, hunting can easily fail, or game can become rare because of environmental hiccups. This happens more often than you should think - there are times when deer can't be found for weeks.…
Yes, one can use intermittent fasting to lose weight, but weight-loss usually only kicks in after 2-3 weeks. Citation needed. I personally know people who've lost weight long term with quite brief periods of intermittent fasting.
Anecdote alert, but I started doing alternate day fasting after I read the study, then 22 hour a day fasts after I read that people were having results with that. Went from 235 to 185 in 2 years (6' tall, fairly large build.) I'm not strict, and I go off it whenever I'm bored or severely tempted.
I count any drink other than water as a snack, and watch the bread, potatoes, and cornstuffs when I am eating. Who knew it could be this easy? I hadn't really been an overeater for years, I just had never had time to starve.