Is "Fast and be healthy" an authentic hadith, and have some scholars authenticated or weakened it?

The hadith "Fast, and you will be healthy" is weak and transmitted through chains of narration that are not authentic. The narration from Abu Hurayrah, although its narrators are trustworthy, is weak because Zuhayr ibn Muhammad (one of its narrators) had unacceptable narrations from the people of Sham, and this narration is one of them. As for the narration from Ibn Abbas, it is very weak due to Nahshal ibn Sa'id, who is accused of lying. And the narration from Ali ibn Abi Talib is severely flawed because Husayn ibn Abdullah ibn Dumayrah (one of its narrators) was declared a liar by Malik.