I have to agree with half what you say...
I also know a personal friend of mine who has 6 kids, 3 births. One set was Quads. And granted, all she does is take care of them, though lately with most of them in highschool, she now owns a hair salon and works that too.
Losing weight IS hard and keeping it off HARDER. But it really does come down to less caloric intake without starving yourself... plus.. eating more wholesome, unprocessed foods.
She looks stunningly like a younger 30 something old vs 42, her actual age.
It's not just about will power, b/c let's face it, in our society, it's hard to avoid food ads. It's also about pain vs fear. Sometimes, when the pain of being overweight becomes too much, you come to a place where you have to choose... the pleasure of food vs the pain of limited clothes selection or self perception or whatever it is that hurts you or bothers you.
I gotta tell you, for decades, it was easier to just give up. Sure, i'd attempt some exercises and then just give up or come up with a rationale of why. Anyway, it isn't easy but it is doable. it's about willpower + pain = possible change.
now starving yourself is definitely NOT what you want to do. Starvation = fat storing mode / weight gain.
But I believe the minimum calorie intake before your body goes into emergency fat storage mode is around 1200 calories. NOT that you have to do 1200 calories for women, 1500 calories for men, but general guidelines so you don't go under that threshold.
that alone, will make you lose weight. Throw in some strength reps with combination of cardio... you'll be surprised the results. Better toned body and the fat will melt away. But again, you gotta want it bad enough. Add knowledge. Add support. And every pound add it to your victories and you'll get there. or she will.
having said that, you still should improve yourself too. along with her.