At best I can share my experience. On 16 Dec 2022, I went keto (<20g carbs/day) at 92kg (203lbs). In May 2023 I was at 81kg (178lbs). It was only mid 2024 that I hit 75kg (165lbs), sometimes higher and sometimes lower. Frustrated with how slow things were, I wanted to force my body to lose weight faster, and I did OMAD, 2MAD, calorie deficits, no dairy, full dairy, lion’s diet, only eggs, butter fasts… And I did not lose (or gain) an ounce over all those months. In 2024 I figured I’d hit what is called a plateau in terms of weight. But my jeans jumped from W33 to W31 - with no change of number on the scale. The beginning of 2025, I began wearing Levis W30, and I even picked up some weight on the scale. In the mirror, I saw my shoulders were finally wider than my waist. Just over the past 3 months I’ve noticed I’d clearly lost fat in my lower back and ‘love handles’ - but my weight is still pretty much the same on the scale. And I look fine in my clothes. I do not work out - at most 60 push-ups 2x/wk - when motivated - but I do walk a lot.
Vanity points set aside, I can now walk up a steep hill speaking with the person next to me. Before I couldn’t talk and walk without being out of breath. I can cut, carry and line up wood in an afternoon without stopping. My resting blood pressure runs around 107/67 (I’m 58). I always take the steps in the metro/RER (here in Paris) - 50 at a time is not an issue. I have great concentration at work and am significantly more efficient now than before, handling stress much better.
What I’ve come to accept & understand:
- the number on the scale doesn’t really mean much
- body fat, water & lean mass ratios on my scale mean even less
- BMI is yet another number, though the extremes can signal danger
- I’m only realising now the significance of other health improvements that should outshine the number on the scale or the bit of tummy that’s still holding tight
- no matter what I want, my body decides what happens, when it happens &where it happens, so no use forcing things because I’m sure it knows what’s best
- what I see in the mirror and how my clothes fit are undeniable progress markers
- it took me 16 years to go from 71kg to 92kg. So, doing the reverse will take time, too - counting in years
The only point i’ve never wavered from is a fatty-meat-based diet with never more than 20g of carbs per day. I’ve gone from keto, to ketovore, to carnivore, to fruitocarnivore 
(seasonal figs, strawberries, citrus fruit from the garden) but never ever more than 20g of carbs per day.
The key points of my success are diet consistency and patience.
You say “I quit keto” - if this means you’ve gone back to the S.A.D. with high amounts of carbs, mixing fat & sugar, low protein & saturated fats and consequently foods with lesser nutrition (beans, oatmeal, bread, pasta, rice) this could explain your experience of gaining in the waist
You say ‘I seem to lose a lot of muscle’. Related to the previous point, are you eating enough animal protein? I aim to eat 130-150g of protein per day and notice no loss of muscle or strength - very much the reverse.