There is a lot of research backing small fasting windows though, releasing growth hormones etc etc. I also find it to help people stick to a certain window so they dont go over their calorie goals by eating them all early in the day and being hungry later and stuffing more food. Lyle Mcdonald talked about a lot of research backing small fasting windows due to the fact the body doesnt get in a major catabolic state till I believe 72 hrs, Id have to look at the article. But he backed a lot of stuff the guy mentioned, w.e his name is, on the leangains.com site.
the only point i can agree with is IF is very efficient at meeting caloric goals because of less feedings. Easier to not a)cheat and b)count . . . . . but may i remind you that you could have say 2 feedings or 3 feedings daily without ever actually fasting. If your only feedings where say PRE and POST workout . . . . this would cover your bases.
Growth Hormone's effects are overstated. . . . you need to be fasting for a significant period like mentioned above before you reap their benefits. DR.JB's research on IF stated GH was elevated after the 22-24 hr mark. Secondly, the amount of increased GH is within your physiological limits, sort of like using peptides but likely much weaker. This would have a limited to ZERO effect on anabolism, but you might see increased efficency fat burning. Synthetic GH is dosed above 4-7iu's daily minimum to see size gains, and i wouldn't even imagine IF could compare to even 1-4iu of GH. . . & at 22 + hours of fasting.
Finally it's important that i stress that IF has NOT seen significant research and only now are studies slowly creeping out. Your best bet is to follow "bro science" or field tested information on it. . . . that is until the scientific community gains better insight into it's effectiveness.
Now i've used IF on and off for the period of 2 + years. I've experimented with 16/8 , 20/4 , 22/2 , and full day fasting protocols.
Benefits (from my experience)
Easier dietary compliance
Easier and more accurate macro counting
Hard to overeat and reach a surplus (when cutting)
works with those who tend to binge, playing into their tendecy to overeat instead of fight it
great way to loose "scale weight"
Calorie cycling
Carb Cycling
Negatives
EXTREMELY muscle wasting . . . . i lost insane amounts of muscle when comparing to 3 meals and 6-8 meal a day dieting protocols.
Working out in a Glycogen Depleted state is not beneficial to hypertrophy.
GI upset from 1300 kcal meals
Hard to even cram defecit calories in 4-6 hour feeding windows.
massive crash post meal #1
very hard eating style to explain to loved ones and friends
For further credit, check out precisionnutrition.com ebook on IF . . . published by JB one of the biggest names in nutrition. Probably the best and most scientific evidence on various IF methods.
Cheers