TLDR - FDA granted market clearance based on the paper linked below. Which was a double-blind, randomized, placed-controlled study. With a success criteria of 3 inches and 35% individual success rate which was exceeded. There were no dietary or exercise requirements placed on patients.
I found this clinical trial paper published in Lasers in Surgery and Medicine 41:799–809 (2009) which details results of the double-blind, randomized, placebo-controlled, multi-center trial of non-invasive body slimming ZERONA.
Study Design/Patients and Methods:
Double-blind, randomized,
placebo-controlled trial of a 2-week
noninvasive laser treatment conducted
from May 2007 to June 2008 across
multiple-private practice sites in the
United States of America. Sixty-seven
volunteers between the ages of 18–65
with a body mass index (BMI) between
25 and 30 kg/m2 and who satisfied the
set inclusion criteria participated.
Results:
Participants in the treatment group
demonstrated an overall reduction in
total circumference across all three
sites of 3.51 in. (P<0.001) compared
with control subjects who revealed a
0.684 reduction (P<0.071745).
Success criteria as defined by the FDA:
The overall study success criterion,
established by Food and Drug
Administration (FDA), was defined as
at least a 35% difference between
treatment groups, comparing the
proportion of individual successes in
each group. It was determined by the
FDA that a reduction of at least 3.0
in. was clinically meaningful.
From the results (refer to the paper) 62.86% of the test group met the individual success criteria of 3 inches.
It's a long enough paper, so I've deliberately tried to display the most relevant information to the question.
Also of note is this passage here, and I'm not a doctor, but refer to the context yourself if you think I'm taking this out of context:
Discussing the basic principles of
laser therapy as described above could
help guide further investigations
towards uncovering the exact mechanism
employed by laser therapy that
ultimately results in the formation of
the adipocyte membrane aperture.
It would seem from the quote above the exact mechanism is not entirely know. That doesn't sound comforting to me.
Just found this:
The FDA granted market clearance
following the completion of a
placebo-controlled, randomized,
double-blind, multi-site clinical
investigation evaluating sixty-seven
study participants. The results
obtained from that study demonstrated
an average inch loss reduction of 3.65
inches across patient's waist, hips,
and thighs in as little as two weeks.
The clinical trial, absent of diet
restrictions, exercise requirements,
or any other adjunctive components
properly illustrated the clinical
utility of the Zerona and set the
precedent on how aesthetic devices
should be evaluated.
It would appear from the above that the study I have mentioned in my answer was the one used by the FDA to allow market clearance. And further to your question (and as per quote above) the trial was done
absent of diet
restrictions, exercise requirements,
or any other adjunctive components