Ive lost over 100 pounds within the last 8 years and now im trying to maintain my weight but also build muscle. Should i eat in a deficit or in a surplus? Ive been so focused on protein that i also need to watch the calories
First, the fact you've lost 100+ lbs is AMAZING!!! Well done, not only for the feat itself, but the time and dedication required to make that goal a reality!
Second, let's address a real mind-*beep* which is about to jump out at you: building muscle is almost invariably going to mean gaining weight. Part of that gain is the muscle itself; part is increased water; part is, unfortunately, body fat. We can take steps to minimize the fat gain, but after so long spent trying to lose weight, just be prepared for the psychological hit when the scale starts to read the other direction. Doesn't have to be a lot; 5-10lbs of muscle (and water) can radically change our appearance.
(There's even the possibility that your weight can stay the same if you continue to lose fat as you gain muscle; I do not know how much more fat you may still be carrying around.)
I would recommend spending a few weeks eating at maintenance while engaging in a progressive strength training program. The increased calories (going from loss to maintain) will help fuel your workouts.
After 6-8 weeks, once eating at maintenance has started to feel more normal, then we can talk about slowly increasing calories, but even then starting by only 100 per day or so.
Tai Chi helped me create more muscle all over and I feel MUCH better overall.