Student or Learner
Does this "long" means "in advance" or "for a long time"? "In advance" doesn't always mean "for a long time". I think it means the former.
24)While some things certainly help burn extra calories, do not think they are an easy way out. For instance, caffeine might help you lose a few calories, and you start to think along the lines of "oh well, if 240 mg will burn an extra 10%, let's go for 500mg." You may end up experiencing trembling hands and sleeplessness long before you start going down a size....
How can you tell it from the meaning of "in advance"? Why is it "for a long time"?
No, Mike seems to have meant 1, not 2 and the two are different. You seem to mean 2, makeing me confused again.
1. You may end up experiencing (for a long time) trembling hands and sleeplessness before you start going down a size....: You experience it for a long time and you start going down a size.
2. You may end up experiencing trembling hands and sleeplessness much before the time you start going down a size....: You experience it (maybe for a short time, not lasting long), but much before you start going down a size..
It could mean either 1 or 2. A appears a long time before B. It doesn't really say whether A lasts up until B or not, though one would normally assume that it could.
"Long before" means "a long time before", not necessarily "for a long time [before]".
Remember - if you don't use correct capitalisation, punctuation and spacing, anything you write will be incorrect.