we KNOW what to do in order to lose weight

Yes, we KNOW what we have to do:  we just have to make ourselves do it.  We have to turn ourselves into fat burners, and when you've reached this age, it can get tricky. 

Most middle-aged women have damaged their metabolisms by trying to adhere to what we THOUGHT were valid recommendations for a healthy diet, and then -- when that proved not only to be empty rhetoric, but downright harmful -- we restricted calories time and again, in order to try to combat nature.  A lot of us MADE OURSELVES into carb burners through decades of a low-fat diet, which effectually turned off our fat-metabolizing enzyme production.  Dr. Wong tells us that we begin lowering production of ALL proteolytic enzymes at age 27 ... so at age 57 it may be darned hard to start making the "right" ones again.  Dr. Donaldson doesn't say the same thing in so many words (i don't believe that the action of systemic enzymes was well-understood in his day), but he wrote about the magical age of 33, when he started seeing the effects of aging accelerate.

Changing over from burning carbohydrates for energy to primarily burning fats, then, is going to be WORK.  If the individual has a rigorous schedule already, and struggles to find the energy to meet it, s/he may experience difficulty in "getting over the hump," which is generally known as the "low-carb flu."  Some people, in fact, take an extended time to get past this , indicating that their metabolisms are the more screwed up.  However, look at it this way:  would you prefer to spend a couple of days (best case) to a couple of months (worst case) with lower energy reserves, or would you rather restrict calories FOR THE REST OF YOUR LIFE, in order to avoid the damage which results in diabetes, NAFLD, senile dementia, heart disease, Parkinson's, etc etc etc....

When i was 30, i wouldn't have HAD to commit to either a glucose-based or a fatty-acid-based metabolism -- at that age i seemed to have pretty robust metabolic flexibility, compared to a lot of young people we see nowadays, who grew up swilling quantities of sodas and fruit juices.  When this flexibility fails, however, one's choices become far more limited.

I'm sure my readers will have observed that every succeeding attempt at weight loss is more difficult and less productive than the one before it.  What it boils down to is, we don't have time to waste in accomplishing what we want.  In order to be able to do the everyday tasks that life requires, we need to create the strength and agility NOW.  We have to make sure our bodies are not overburdened with fat, weight-damaged joints and deteriorated tissues NOW.  Trying out the techniques which younger people swear works for THEM may put us so far behind in the race that we'll end by giving up in despair (e.g., the "leptin reset" protocol which a certain young woman said finally worked for her ... AFTER she put on a dozen pounds!) -- that just ain't gonna cut it.

I -- WE -- know what we have to do.