I weighed Lada tonight, to see how he's getting on with the Oxbow Essentials food. Tonight he only weighed 96 grams. That's 10 grams down from the 104 he clocked a month ago (June 6).
Apparently, though, it's normal for a hamster's weight to fluctuate with as much as 1-12 grams, so I don't really worry yet. I only worry about the fact that he's so small, but I guess he's just built that way.