Unfortunately pretty slim results—pun not intended. I wonder if a year-long program would move any of the other indicators?
Body weight and energy intake decreased in the time restricted group (–2.6% ± 0.5; –341 ± 53 kcal/d) relative to controls over 12 weeks (P < 0.05). Systolic blood pressure decreased in the time restricted feeding group (–7 ± 2 mm Hg) versus controls (P < 0.05). Fat mass, lean mass, visceral fat mass, diastolic blood pressure, LDL cholesterol, HDL cholesterol, triglycerides, fasting glucose, fasting insulin, HOMA-IR, and homocysteine were not significantly different from controls after 12 weeks (no group × time interaction).
The body figures out a way to maintain homeostasis if calorie intake and activity are more or less the same. The bodyweight reduction appears to be a function of the caloric intake - if it helps people control their calories, that is a plus for many people.
My best success with IF comes with an increased protein intake relative to carbs; for me at least, my caloric intake will go down from just the higher protein intake and less carbs - meat is just more satiating. The IF contributes furtehr to that. I can continue building muscle as well with this protocol if I am careful no to overdo other activities. Nothing keto-like in terms of carb restriction, but the combo of intermittent fasting combined with increased protein intake (and fewer carbs), in my opinion would produce greater results.
I also like to do my intermittent fasting depending on activity level - if I am weight training and mountain biking in the same day, I'm just not going to do it; I'll be stressed out. For me it feels appropriate on days where I'm just weight training or I otherwise have low activity.