I think he's saying after 2-3 weeks of intermittent fasting, not fasting for 2-3 weeks at a time intermittently.

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.