Since I've just started, I'm still so unsure of everything and it's hard to have the assumption that I'm fine regardless. But I like the idea of operating under that assumption; it would definitely reduce some stress!
Here's the secret to being fine regardless. It's staying in the present moment where everything is always fine. You're breathing, you have clothes to wear, people (or pets) who love you, gravity - so you don't go flying off into space, food to eat, a bed to sleep in, a pretty sky, laughter, seasons. If you can slow down, take some breaths, and focus on the present moment, it pretty much rocks, even some sadness or boredom, or other emotions, because they're part of it. It's still fine.
Things only feel really frighteningly not fine when we are believing painful stories about past and future, in other words, fantasy about what the tight clothes MEAN. It's often something along the lines of, "I always..." or "I'll never..." or "Now I have to..." or "Everyone will think..."
Whatever the painful, scary thought is, it's not actually happening right now. You're projecting past experiences or worrying about future ones, assigning meaning where there isn't any. That unquestioned thought pattern is the problem, not how your clothes fit or what you weigh in this instant, which is a variable at the very least. It will probably be different tomorrow, or next week, or next year, and you'll make up a different story to go with it.
You're fine as long as you realize that you're the storyteller and you're not taking your script too seriously. Sometimes it's entertaining. "I can't believe I'm telling myself the one about becoming a homeless cat lady in fat pants again!" Sometimes it's really believable and genuinely scary, but that just means you're a good storyteller, not that there's something to be afraid of. If you can create that small bit of space between you and your stories, everything changes.
Thoughts determine mood. Mood determines behavior. Behavior determines results. Most people fiddle endlessly with behaviors (calories, points, portions, numbers, rules) and wonder why they aren't getting any results. If you identify as an emotional eater, maybe you also address moods to a degree, naming them, attempting to change them with behavior.
BUT if you can back all the way up to the thoughts that start your whole experience snowball rolling, everything can change in an instant.