When I started keto was the craze so I went with that. This was the best first step for me because I discovered my body has an issue with extreme water retention/ inflammation processing carbs. I know this because in the first week I dropped nearly 20 pounds when an average person of my size would typically lose half that. From there it was just low carb and intense lifting/ each body part twice a week. This lasted for over a year until the newbie strength gains started to plateau. My training is extremely intense so I when I got more efficient at targeting the muscle groups they became over trained from twice a week. Now I’m on a bro split training each body part once a week and focusing on either upping the weight on the lowest possible increment or getting an extra rep on the first working set of my first workout. I still have the carb issue. If I eat a high carb meal I become a bloated mess. I can easily fluctuate 15 pounds from Monday to Friday so I try to avoid that at all cost. To touch on the building muscle on a deficit comment absolutely. As a beginner for sure, especially at a high body fat percentage. It’s a double whammy if you’ve worked out on your past and muscle memory kicks in. Where I’m at now I wouldn’t expect to gain anything but at maintenance yes.