From their analysis<p>Definition -- The 16:8 protocol is a type of intermittent fasting (known as time-restricted eating in the scientific literature) that involves abstaining from calories for 16 hours of the day, and then eating within an 8 hour window. The eating window can occur at any point in the day, but many people choose to eat between around 12 p.m. and 8 p.m.<p>Summary and conclusions -- Following a 16:8 time-restricted eating protocol seems to be a viable tool for reducing body weight and body fat, with and without caloric restriction. Some studies have found that 16:8 can preferentially reduce fat mass while sparing muscle, but further research is still required to confirm this. At worst, this limited evidence suggests this protocol can be about as effective as standard dieting, and potentially psychologically easier for some people.<p>----
These are all small studies but it's as you expect for a diet program that is essentially free, no one has a stake in selling it.