The thing about WLIs, when they work, is that they really do work for you mentally as well.
When I was taking them, I’d look at my husband going back for seconds, or raiding the cupboards in the evening or suggesting he nips to the shop for some treats for later when we’re watching the traitors or whatever it was, even having a beer at the weekend, and it would just seem like such alien behaviour to me. I’d be like ‘why would you, you’re not hungry, you had a big dinner, why would you even be thinking about it?’
I really genuinely felt like that, and I had to remind myself that prior to the jabs that was exactly what I’d have been doing, or wanting to do and struggling to stop myself. I felt so far removed from those cravings and habits. I didn’t say anything, had just enough sense left not to, but do remember the feeling of ‘I’m cured, I finally see the light’.
Im not taking them now because I’m one who couldn’t take the side effects, though I’m bloody grateful I did get to take them and was able to lose a lot of weight, most of which I have kept off up to now. But the battle is back and I absolutely remember I am a person who struggles with this stuff and always has, and without the drugs always will. I usually manage to exert some willpower now, but only because I know what it’s like to be where I want to be, and what it cost me financially and in terms of the side effects to get there so I’m not going to throw it away. I will never rule out having to use them again because I know that my food issues are life long.
So, whilst shes definitely being insufferable, I can empathise with how your SIL is feeling like she’s finally cracked it. The drugs suppressing your appetite was only one part of it. In a way it’s a bad thing how thoroughly they convince you that you’re a changed person who had made all these lifelong lifestyle changes and could never ever go back- it makes it all the harder when you stop and think ‘oh no, I’m still me, I absolutely could go back at any time!’
Of course she should have the sense to keep it to herself and realise it’s not some great new willpower she’s found, it’s the drugs working now they’re designed to. Hopefully she’ll realise.