N=1 but in 2017 I lost over 100 pounds in 8 months by changing to a keto + IF diet and I've kept it off. I lost 10 pounds in 10 days and 20 pounds the first month. At around six weeks I became 'fat-adapted', a long-term metabolic transition to primarily burning fat instead of carbs (glucose) for energy. I didn't start with IF but at around that point I sort of fell into intermittent fasting because it just felt right. I'd heard about IF but never had it as a goal because it seemed impossible since I'd been hungry my whole life. But limiting carbs with keto controlled my blood sugar to the extent I was almost never hungry which made IF trivially easy. So if you're trying IF and struggling with hunger pangs, try managing blood sugar by reducing carb intake.

The combination of Keto+IF worked so well for me, for a while my calorie tracking switched from the usual preventing eating too many calories to ensuring I was getting enough, which was certainly never on my bingo card. After a lifetime of being a slave to hunger it was liberating to suddenly feel effortlessly in control of diet and my relationship with food changed completely. Then at around 90 days my palate shifted, meaning I even lost my taste for carbie foods. If I tried a small bite of something carb-laden that I'd loved my whole life, it didn't even taste particularly good to me anymore. I also became hyper-sensitive to sugar. Sugar-soaked foods just taste poisonously over-sweetened (which they kind of are). A slice of apple now tastes as sweet as I'd ever want, like a dessert that has extra sugar-added.

In the 8th month I reached below my ideal 'dream' weight and even saw abs appear for the first time in my life! I transitioned to maintenance mode but stayed keto because being in a blood sugar controlled state felt so amazing and not just physically but also mentally and emotionally. At around a year I went from strict keto to low carb for life which I still am 8 years later. When I started that was unimaginable. I saw keto as an onerous regimen that I'd endure if it worked and stop the second I wasn't overweight. But during the journey my metabolism, palate and food preferences changed so dramatically, I was basically a different person when I arrived. Those first few months when I was rigorously tracking every calorie in an app and managing intake with measuring cups and a kitchen scale felt like a burden but were actually invaluable skill-building. After a few months all that process became automatic so I didn't need to constantly track and by six months I got to the point where I don't even think about it consciously. That early rigor helped me get so in sync with my body and able to sense where my metabolism is in its natural cycles that now I just eat when necessary and convenient for my schedule. This often ends up being IF but it's not intentional on my part, which makes me think maybe IF patterns evolved in the hunter/gatherer era as part of our natural biological rhythms. Due to habit and carb-laden factory foods I'd never been able to access those rhythms until I made the conscious effort to break the patterns I'd been raised in.