Oh its certainly working. Ive so far lost 35kg since last year when I hit my peak weight of 147kg. I have introduced exercise and the gym in the last few months now as part of physio for my back problems. My BP is coming down, hba1 is down. the back problems and OSA are pre existing from whole life, so dont expect them to change much from weight alone.
I already cook/meal prep for my actual meal everyday, and always have as I love cooking.
My main weakness is... all food

If I have food that is too easy to snack on, and that I very much love, I struggle a lot not to eat it/eat it instead of anything that I have to cook. But even when I have all food that needs to be prepped, I will eat it more often, or in larger amounts because I know how much I like it

. So having a cupboard of diet meal shakes and light/healthy snacks pre portioned (sometimes home made) makes it a lot easier for me to stick to when while I do enjoy the flavour/they satisfy a lot of my cravings for other things, and they are somewhat giving me the nutrient/vitamin mix without me having to work it out (while having limited overall intake), it's an easy way to be in a large calorie deficit consistently.
Also, they are quire cheap. At full price, which ive never paid, they are £1.60 a meal but, normally I've paid 60-90p. Which bas been a big boon to me at the moment since I have been off work with the aforementioned back problems, I couldn't even sit at a PC for more than 20 minutes back in December.
It has helped my portion control too, since they are so small, it makes me want smaller portions of actual food/feel fuller with smaller amounts.
Generally I've slowly changed a lot of food habits while doing this, eating a lot more beans, pulses, fruit, seeds in stuff, yoghurt and more limited amounts of the things like meat/cheese etc. So hopefully when I settle back into "normal food" its already a habit/the things my body tells me to eat are the healthier options by default - This has already had an effect on what I buy/want to eat without me actively thinking about it nearly as much now, so I think thats working too.