Roughly speaking: "Act normal" vs "Use Beeminder" vs "some alternative intervention". Basically, I expect to see "do something different" produce results, at least for a little while, for almost any value of "something different". Literally anything at all that didn't make it clear to the placebo group that they were the placebo group. Maybe some non-Beeminder exercise and intake tracking. Maybe a prescribed simple exercise routine + non-Beeminder tracking.