Cancer center to patient-“It’s good you have extra weight” (BMI 47). “You need that when you have cancer. Don’t try to lose weight.”

I guess the logic here is:
Keep a lot of on board energy stores at the ready so you can tap into them as cachexia sets in. It might give you a few extra months as you whither away.

Let’s not confuse weight loss that occurs through starvation (like when someone calorie counts which is self inflicted cachexia), to fat loss and weight normalization that occurs when eating a proper human diet which I diet with much less grains, sugars and seed oils.

Incidentally, sugars and seed oils is exactly what is is found in dieticians favorite nutritional supplements for cancer patients:

Fun fact low carb diets are weight gain diets to the undernourished.

Low carb diets actually maintain obesity quite well (although after initial but partial fat loss) in some. It’s called a stall.