This is a question I can only begin to answer.
I’m just now, in mid life figuring out how to diet for the first time. After a frustrating learning curve of about 8 months, I have discovered first hand that a weight loss diet without difficulty is known as a scam.
Skipping beer, missing muffins, bran bonanza, salad under meat, all kinds of almonds for snacks–each phase has been a failure in terms of slimming effects. Each phase has included adequate supplies of vitamin Ch (chocolate) and no serious exercise, however.
Serious motivation is key, I’m sure, but at the moment my main reason to diet is to be able to live a little longer in order to have MORE beer and chocolate. Consequently the progress of my weight loss program can be succinctly described by this snazzy graphic representation: /\/\/\/\/\/\/\/\/\

Maybe the primary reason it’s hard to lose weight is that our bodies just don’t want to let go of all that extra fat easily. Biologically, it’s money in the bank.
We’ll be the last to starve on the lifeboat. We’ll survive long enough to eat all our friends in a crisis.
Hunger is pretty powerful. I suspect that getting cozy with hunger has to be part of losing weight, and that’s gotta be hard.