the weight loss is associated with more cancer and loss of appetite with the more severe cases. the cancer causes the loss of weight. Therefore correlation rather than cause.
Precisely, Paul. It is known as "cancer cachexia". Many of us here, like you, by the time we've reached the age where PCa becomes common, we've probably watched parents, as well as siblings and close friends "waste away" and die, often from cancer. Malnutrition is common in later stage cancer. So is living living on liquid nutrition and likely forced high calorie diet, as they tend to eat so little.
BTW Ken and others, several of my relatives have had good luck with the Keto diet. None of them are post ADT, but I'm guessing that outside of cachexia, weight loss is weight loss.