成唯識論述記 4.492

4.492

述曰：設許身是食，理亦不然。無色界無身，汝之命根無能持故。若言：眾同分能持命根等，皆無實體故，亦非是食。

The Commentary states: Even granting that the body is nutriment, the principle is still not correct. The formless realm has no body, so your life faculty has nothing to maintain it. If it is said that generic similarity can maintain the life faculty and so forth, because these all lack real substance, they are also not nutriment.