almost never

(yea, me! only took 35 years to learn it! lol ~ self)

When my current size jeans feel loose, I'll try on the size 10's. If they fit, I'll weigh myself in the morning, after peeing, not the week of TOM, to see what sort of weight that equals; then I'll leave the scale alone until I can wear size 8's, and repeat process.

Scales are eeeeeevil for chronic dieters. They'll depress us one day and give us "reasons" to cheat the next.

Also, I avoid people who torture or tease or nudge me "helpfully" about my size or weight, which makes life ever so much more pleasant!

Why an obsession with what a "real weight" is...are you trying to "make weight" for your next professional boxing match? I say, if if motivates you and makes you feel better to turn the whole scale at home down 15 pounds, that's still fine. Your weight loss relative to your start point will be the same. If the clothes are looser and if you're in ketosis and if you know you're not cheating, you'll lose the fat. It'll happen sooner, or it'll happen later, and the whole while you'll feel better for avoiding carbs.

Best of luck!