I read about periods of food refusal in this topic. My snakes do never refuse food (except some of them when they have to shed skin - but most of them also eat in the shedding period).
Could this be because of the diet I feed my snakes? About 95 % smelt and the other 5 % exists of chicken heart, salmon or pollock. This is complemented with a multivitamin/mineral product (I added some extra vit. B1 to it myself) every second or third feeding. I feed on average once a week (the 2 years and older snakes) and about every 4th day for juveniles. I only give pregnant females every now and then one pinky.
I do this for about the last 10 years or so. Have good breeding results and healthy snakes that tend to live long.