I understand what you’re going through, I have a small frame and, over the years, wildly fluctuating weight which my self-esteem is extremely sensitive to. I’m proud to say I’m a little less judgemental of myself as of late - I won’t lie and say I love myself and my body to bits, but it’s progress that I hadn’t believed existed until it creeped up on me.
What’s important in reality is being healthy. I absolutely understand the sugar addiction - a million factors contribute to this, for me it was hormones, mood and anxiety/ adhd (these things can also make your brain crave the gratification of food and sugar too), meds, and low energy. Also sugar’s just addictive it would seem. None of these things reflect on you personally, and compassion towards my body was hugely comforting for me - it’s simply asking for something it thinks it really needs. Start by eating decent food that keeps you full as hunger exacerbates your body’s want for sugar, use flavours you like and try to put a little effort into what you have where you can, whether that’s cooking the food or getting excited to go out. And on that note, others aren’t thinking about your appearance, they’re often too busy thinking about their own… Sometimes you need to throw caution to the wind and enjoy good company.
Exercise is another slippery slope and it all depends on your body. After years of thinking ‘real’ exercise was running until you wept and endless cardio I discovered strength training videos on youtube. There’s also swimming, stretch, walking, etc, that are kind to your time and wallet. Exercise isn’t important because it keeps you in shape, but because it stimulates your mind and body.
It’s a little wacky, but doing things you love matters. For me that was art, and I took up life drawing and gained a sense of admiration for the many shapes a body can create. I hate to get artsy but the volumes of the human body are unlike anything! Somehow, objectifying a body and appreciating tiny beauties in others helped me, and helped me inhabit my body and visualise it in my minds eye differently. A figure in an artwork isn’t perfect because it looks like it doesn’t enjoy bread, but because it’s asymmetries make it empathetic and dynamic. (It obviously doesn’t have to be art)
This was super long and a little too much about me but I genuinely think this stuff had merit. In short, try to remind yourself what your body enjoys and how your mind can share in it.
Best of luck :)