To make it simple I will narrow it down to only two examples for the sake of discussion: low carb and weight training.
There are most definitely trend/fad driven aspects to both of these, and when they take hold, it is like they become a religion (complete with sins, shaming and purity/cleanliness).
I came across a post where the OP didn't aesthetically like her bodyshape after strength training. Instead of supporting her and helping her to find a happier healthy alternative, she was shamed into believing she was brainwashed by the patriarchy for not wanting to continue with it.
It seems once something becomes socially popular, there can't be a word said against it.
And of course, these attitudes (complete with studies and data) will change every 5 to 10 years.
Some women just don't really like it, they might prefer football, yoga, pilates, cycling, dancing, etc. A balanced level of fitness and eating is possible for almost everyone.
Alternatively many love strength training, and that's great!
But there is such a fierce disapproval of any woman who isn't interested in strength training, with accusations that she is a puppet of the patriarchy which tells her to stay thin, weak and passive.
Many, many women who don't want to lift weights ARE strong, intelligent and confident. Whilst there are health benefits to lifting, the same could be said for many other forms of exercise. If someone doesn't like the look of their body after lifting, they are not brainwashed idiots, nor should they be shamed into preferring it.
Same with attitudes to food. The answer to every ailment or issue is currently low carb! Or no dairy! If you say you are happy and healthy consuming them then you are 'fooling yourself'. Many people have excluded both and found no difference to their IBS, acne, weight issues and general health. Some even come out of it worse off.
We need to accept that we are all different, and our bodies feel better doing different things. If a woman doesn't jive with lifting weights, then accept her opinion and encourage her to find what she loves. Nothing is sacrosanct, and there are so many people making huge profits out of our health and diet insecurities, including lifters and fasting guru's, it ain't just Big Sugar that's after your cash.
Creating judgement and division between women about their fitness & food choices is far more insidious and controlling. Whilst I am no fan of food additives or swimming in salt and sugar, I don't think food is necessarily 'cleaner' if our great great grandmother's granny ate it, either.
Most if it smacks of competitive restricting, class insecurity and an almost religious dogma. At the bottom of it all, as usual with the human species, is most probably the terror of mortality. And if we can just eat cleaner or lift more we can live longer and better than those lowly idiots who haven't a clue! Perhaps the 'brainwashing' is far more complex than the mere patriarchy,
It's so all or nothing these days.