As a point of comparison I'm a large man and fairly active with endurance sports so I have to consume about 3100 kcal/day (with no fasting) to maintain body weight.
Sunday 10pm - Tuesday 10am - No food.
Tuesday 10am - Tuesday 10pm = 1500
Tuesday 10pm - Thursday 10am = No food.
Thursday 10am - Thursday 10pm = 1500
Thursday 10pm - Saturday 10am = No food.
Saturday 10am - Sunday 10pm = 3000 (Sat 1500cal, Sun 1500cal)
6000cal.
Though I agree there probably is some fuzziness in those 1500 days that I'm not properly accounting for.
Whenever one feels tempted to utter “it’s all in your head”, my advice is to take a step back and reflect on how little I know about the circumstances of others, and then, you know, maybe just keep it to myself.
"Hormon-typical" individuals have an easier time shaping their behavior because they don't face imbalances that complicate adherence. For them, sticking to a program is trivial. Combine that with lack of reflection, and many of these individuals delude themselves into thinking their success of following simple programs (which are simple in design, and only difficult in adherence) is somehow an accomplishment worthy of note. Low-empathy individuals, in particular, often interpret this as evidence of their own superiority, while dismissing others as mediocre.
So you see such comments a lot, because many people are "hormon-typical" and also low empathy. See any discussion about diet, fitness, Ozempic, etc.
But I've always been a skinny person. Maybe it is less exhausting if you have lots of fat to run off of.