Snakes have metabolic rates far below those of birds or mammals of similar size, and a large meal can fuel a ball python for a long stretch. In the wild the species follows a seasonal rhythm in West African savanna, becoming much less active and feeding little during the dry months, when rodent prey is harder to find and the snake stays deep in burrows.
Captive animals keep the rhythm. Fasts of one to three months are commonly reported in otherwise healthy adults, and breeding males may go longer while searching for females. The reliable signal of a problem is not refusal itself but weight loss, sunken body outline or lethargy alongside it.
What is often got wrong is the cause. Extended fasting is regularly treated as a symptom to be corrected with warmer temperatures or forced feeding, when in most cases it reflects season, temperature and reproductive state. Persistent refusal accompanied by measurable weight loss is a different matter and does warrant veterinary attention.