I think it’s noteworthy that when we look at the 13 dhutaṅgas:
- paṃsukūla : abandonned robes
- tecīvarika : three robes
- piṇḍapāta : collection by means of one’s bowl
- sapadānacārika : food collection without skipping houses
- ekāsanika : a single meal
- pattapiṇḍika : everything within the bowl
- khalupacchābhattika : no longer accepting any extra food after having started to take the meal
- āraññika : to remain in the forest
- rukkhamūla : to remain beneath a tree
- abbhokāsika : to remain on the bare earth without shelter
- susānika : to remain among charnels
- yathāsantatika : to sleep at the alloted spot
- nesajjika : to renonce to the lying posture
…not one of them causes acute pain. In other words, even when you get into the most strict (or close to ascetic) practices that the Buddha allowed, and didn’t even insist on, you still don’t find any acute pain there.