you have not reached the least amount of food you can eat.
The least amount of food you can eat is zero. And if you are fat enough, you can live just fine on zero calories of food for weeks.
You will feel weak... because your body can only process fat at a specific rate- no sudden boosts of glucose...
But keep in mind that doctors feed patients glucose directly thru a vein if they have had bowel or intestinal surgery and they have to keep their digestive tract quiescent for healing.
You can live on pure glucose directly in a vein.
So you have "plateaued"...
Analyze your activity level, and your intake.
Whatever amount of food you are eating, right now, is the amount of food that it takes to maintian that body weight at that level of activity.
Your metabolism will lower, but only if you are sedentary.
If you want to weigh less, you will have to reduce intake further, or increase activity level further.
I am really not shitting you.... as you age, the amount of calories you need to keep going at a given weight drops RADICALLY. By 50, most men can live just fine on a single moderate meal per day.
By 80, slender people are eating a bowl of thin soup per day.
Here's a cute trick- the human body burns more calories per minute SITTING in an unheated pool, than running in a marathon. This is because water conducts heat away from the body 9 times faster than air.... so 70% of your caloric burn is simply to maintain body temperature.
Try swimming laps in an unheated pool. the Water, plus the exercise will burn a lot of calories, fast. And water resistance offers the lowest impact exercise there is.
But again... do not focus on exercise. Try to achieve a higher NORMAL activity level.
Walk places you used to drive. Get a standing desk.
The most effective application of exercise is not extreme exercise that will inevitably cause injuries... its simply a more active lifestyle that does not pass into the extreme.
Focus rather on all the little cheats you don't really count as eating- like that daily latte...
Which can have the same number of calories as a milkshake.
Or that little snack you tuck in just before bed...
Truth- there is no metabolic plateau. Just a caloric plateau.
If you are sedentary, and won't increase activity level... the the only choice you have is less food.
600 calories per day is doable, for weeks at a time.
I find the most important trick is to get to the point where you don't WANT to eat.
Give yourself a chance to Empty Out- and you can get to love the feeling of being hollow. Being able to bend in the middle...
No cookie or burger is so good that I am willing to have to hold my breath just to tie my shoes.