I've been having a bad time with SPD lately. here is an attempt at a user manual for the trends in my SPD issues.
("trends" in the sense of patterns in the data, there is nothing fashionable about SPD)
firstly, humans have 8 senses (actually, many more, but 8 is enough for our purposes). these are:
6. proprioception (where your body parts are in relation to each other. feedback comes from muscles)
7. balance (which way up you are. feedback comes from inner ears)
8. introception (feedback from organs. are you hungry? need to pee?)
the senses that act up for me are smell, touch, taste, proprioception & introception. balance seems unaffected. noise (and strobe lighting) is a problem, but only because it uses extra bandwidth I don't have.
introception (as it relates to food) is basically fucked. I might think I should be hungry because it's 2pm and lunch hasn't happened, but I won't feel it.
proprioception doesn't directly relate to food. if food isn't happening, certain proprioception-seeking behaviours look like a bad idea. I'll probably do them anyway, because running up stairs feels good.
taste is closest-to-normal of all the food related senses, but may be under-stimulated in the moment due to compromise with other senses. I'm likely to want low-smell strong flavours (sharp/salty/sweet/chilli...) alongside plainer foods.
texture is difficult. there isn't enough texture vocabulary to explain. bread is generally bad. 1 wrong texture makes that food inedible, so mono-textured foods are safer. sometimes, certain foods only have an acceptable texture when hot. liquids are sometimes easier than solids, but not coffee. coffee fucks with introception on good days, I don't want to know what it does on bad days.
generally, if my senses are off everything smells stronger. this means exciting food smells are gross.
then there is the other stuff...
nutritional content matters. protein can be hard, but I tend to feel better if I can eat some. fruit is a safe bet, but won't make me more functional on it's own.
also, we're fighting a lot of social conditioning. asking if I'm OK will get a scripted auto-response most of the time. ask something weird. "fish fingers and custard?" doesn't have a script (and due to headcannon, is SPD related in my brain). asking about specific senses might also work (but not introception. introception is fucked).
and then there's the wider social issues. the reason it's hard for me to bring this stuff up. the reason why it's almost impossible for other people. I don't know how to write this. if I write about my experience without acknowledging how I have it easier than my friend, that sucks. but if I speak for them, that might be worse.
the short version? no, you don't really wish you had broken introception to make dieting easier, so don't say it. also, us SPDers come in a wide range of sizes. be the safe person for the SPDer(s) in your life.