This is a good point - I'll caveat this in the post. Most medication/placebo studies tend to involve a bit of coaching in addition to the medication, usually 1 session per month or less with instruction on diet and exercise. So the 25% result is essentially "coaching-lite + sugar pill", which may be considerably more expensive than a simple placebo. This result could be much weaker if it's just the placebo alone.

Not only that, but tracking alone raises a lot of awareness and a tendency to be more "healthy" or compliant.