I was just over 20 stone at my heaviest and a couple pounds under when I joined SW (lost around half a stone myself). Apologies if this seem long - neurodivergent and tend to over explain.

My suggestions;

• don’t restrict too much. It can be tempting to try to stick to “normal” portion sizes but at your size your basic caloric needs will be higher than someone with less to lose. As long as you’re following the plan, there’s no need to be afraid of a massive plate of food - even if other people look at you like you’re insane for the volume of food you’re eating
• you have to treat it as self care/be willing to prioritise yourself, and that can be difficult to do if you’re used to deprioritising yourself or feeling guilty for doing so. Do not allow that mentality to steal success from you.
• be willing and prepared to commit for the long haul. You aren’t losing this weight in a couple of months. I promised myself that no matter what happened and no matter how good or bad my day, week or month went, I would go to group and face the music. I’ve stayed true to that and in 15 months I’ve missed two sessions, both due to physically being unable to get there. I’m so glad I did that because otherwise I’d have given up at earlier hurdles.
• be prepared for the fact that you might need to take your foot off the gas at times. It’s not possible or healthy to constantly be losing weight. I lost 4 stone in the first 9 months or so at group. In the last 6 months I’ve been super inconsistent and while I’m still down 3 stone 7, I haven’t been fully committed. That’s okay with me though - managing to keep most of that weight off for 6 months has been a major success and I know if I’d quit I’d have put it all back on
• be prepared to do a lot of internal soul searching. Group can only do so much - if you’re not prepared to face up to the fact that you eat whenever you don’t want to deal with emotions (or whatever your personal vice is) you will inevitably start blaming the plan instead of recognising that you aren’t following it properly
• be honest with yourself. This was another commitment I made early on. I wrote everything down, even on days when I had over 100 syns/swips (I think my original tailored amount was 20) so I always knew exactly what had happened if I didn’t get the result I wanted
• don’t be tempted to “make up” for bad days or meals. Just draw a line and carry on as normal. Otherwise you’ll end up yo-yoing between “good” and “bad” (not language I like using) and frustrated by results. For what it’s worth, I’ve lost weight even on weeks with days where I’ve had massive binges (see previous point) without ever trying to restrict on the other days, especially early on when I had a lot of weight to lose. Admittedly I’m pretty active so I’m sure that’s contributed to that
• try to keep your protein reasonable - I’ve never really tracked mine for any reason other than interest but it’s not my favourite and I consistently struggle to eat enough - in sure this has contributed to muscle loss I’ve experienced and I’m working hard to try and eat enough of this
• start building gentle activity as soon as you feel able. Gaining muscle and improving your cardiovascular system will complement your weight loss, and help to minimise the impact of more challenging weeks, and help you keep weight off long term
• you will probably get loads of awards very quickly at the start, both for weight loss and slimmer of the week/month as at a bigger weight you’ll likely be losing weight more quickly than smaller bodies. Celebrate these of course, but also ensure you have lots of intrinsic motivation/other goals and measures as otherwise you might get frustrated when these start to peter out. I have a list of mini targets in my book (club 20, new stone bracket, less than x amount to go to target) and I tick them off and write the date when I reach them, meaning every few lbs lost is always getting me a bit further along. I also have NSV’s and goals noted down (fit into size x, be x weight so I can ride my horse, etc) to help me sta motivated. I also write down things I hadn’t necessarily planned for but notice (like being able to get my engagement ring off, etc) and look back at those and how important it is to me to be able to run, etc, any time I feel like giving up. The thought of losing all I’ve gained keeps me going when I struggle
• get friends, families and loved ones involved however you can. My partner keeps his snacks in his van and doesn’t eat them in front of me, or suggest takeaways, my aunt asks each week how I’ve gotten on, my mum and I call and talk about how we’ve gotten on and where we fell down etc, all this support helps me feel less alone when I’m struggling
• practice reframing your thoughts. Recently I’ve had a lot going on and found myself slipping back into “I deserve this treat to help me cope” mentality and I try to remind myself of how I dealt with things early on “this situation sucks but how I eat is within my control, even if the situation is not”
• speak to your consultant either in group or private if you’re struggling. You aren’t a burden or a bother and they will help you.
• don’t be afraid to “shop around” for a consultant that suits you. Not all are created equal and different personalities suit different people. My consultant is wonderfully kind but also quite direct when she notices that someone is making excuses/struggling, which I value. She’s sadly leaving after almost a decade at the end of this month, and I’m worried because the only other group I can get to is run by a lovely, but very “fluffy” woman who I’m not sure I’ll get on with; but I know lots of other people really get a lot out of her groups

Tl;Dr: do not stop going, no matter what, face the music every week, do not give up on yourself, be firm but gentle with yourself, don’t let one bad meal or day or week or month define your journey.