I'd say fasting once a week would not be in line with a "natural" fast.
Taoism does promote moderation and doing things in balance, but i think it's worth highlighting it also promote the idea of living in harmony with nature (as well as your own human nature).
I highlight nature, because fasting is (or rather was) a natural occurrence in human living.
To use fasting as quick-fix to lower weekly caloric consumption seems rather unnatural. Whereas if you fasted a week or 2 after a couple months of higher caloric eating. For example, most people will naturally eat more fatty, higher caloric foods during winter when it's cold. Having a week or 2 of fasting after winter would seem much more in line with human nature.
Stocking up for winter and running dry near it's end.
While it's possible to always eat moderately these days. Nature always oscillates between highs and lows (Yin and Yang), though rarely in abrupt manners. So to me, what is meant by over-eating and over-fasting is to avoid unnatural extremes. For example by using fasting as a way to allow overconsumption. Constantly jumping from the extreme of over-eating to the extreme of not eating at all.
I think some will read "moderation" and think it means to find the perfect middle ground. Instead of a graph that oscillates, having highs and lows, they'll aim to create a straight line. Eat the perfect "moderate" amount of foods with the perfect "moderate" amount of carbs, fats and protein. But that way of eating isn't moderate at all, in fact you've just created another extreme instead.
If one day you're feeling a bit more hungry, eat a bit more, if one day you feel less hungry, eat a little less. The problem is if your "baseline" eating is messed up, in which case the above idea of eat a bit more or less depending on your body’s signals suddenly doesn't apply.
You'll have to regain that natural baseline so you CAN rely on your body's signals and eat in a moderate non-forced, non-calculated way.
A longer fast can be used as a tool to help recalibrate ones body. Be it taste buds to gut biome to hormone regulation. But that is achieved through a pretty calculated and deliberate re-feeding plan.
It should be pointed out that salt, spices and sugar WILL always mess with your feeling of satiety. Put simply, if you've added salt to your food, you'll delay the feeling of being "full" and therefore eat more. That doesn't mean you shouldn't use salt, spices and sugar. After all, it makes food taste even more delicious. Instead you should be aware of the effect they have on your body. Since it delays the feeling of satiety, one way to deal with that effect is simply to eat slower, knowing your body will be delayed in sending the hormonal signal that makes you feel satiated.
