Holistic flea topical treatment or spray for cats?

I'm seeking a natural remedy to apply to my cat to keep off fleas. So far, in my research I've come upon websites only suggesting how to rid of fleas that are ALREADY infesting, and spraying the yard with a chemical isn't a change at all, it's still a chemical. Garlic is TOXIC for cats, so nobody recommend garlic as I've read some misinformed people telling cat owners to do so. My only other source is a good diet, as fleas only invade animals of poor health. I'm hesitant to believe this, however... parasites are parasites I do doubt they discriminate unless a cat owner of 20 years in holistic care can tell me otherwise.