I lost weight and maintain it without any exercise, dieting and only minimal portion control (which is now super easy and I can cheat whenever I want, even every day).
How I have lost weight, and not only maintained the lost weight, but also continue to slightly lose more, is to be ok with being hungry.
Being hungry is good and normal and if you can get to this point mentally then every meal tastes better, you eat less automatically (some portion control is related, next paragraph) and when you are hungry your stomach has contracted some and you need less food to feel full. Also, you have more energy, and more time (less spent on dealing with food).
To ensure you are hungry before the next meal, eat less and less every time until you understand your body intuitively. Not with measures, but with skill honed by experience, customized information/data to your exact body and life.
An average day (currently), I make an egg/milk (add ice to make a shake) type drink for breakfast and lunch. Sometimes a very light lunch, and then I eat whatever I want to for dinner. Anything I feel like. (anyone can find something super light, just to get you through a few hours, and then be hungry before lunch.)
If in the future my energy level changes? (from more/less exercise or activity) Then so will my hunger status, which automatically adjusts how much I eat.
But feeling hungry has to be ok. I like being hungry for about an hour before I eat a meal.
This is with no exercise at all, none.
Also, when on vacation, if I pig out (not as enjoyable as it used to be) or drink more than usual, then it doesn't matter at all, because if I go up a few pounds, they will shed easily in the next couple days.
--Experiment from the past year.
Last year (summer) I did intermittent fasting, and got up to running 2 miles a day. I lost 15 pounds in a month. I kept most of it off, but limited my running a lot after this, and by December I decided to see if pure strength exercising would be enough to control weight. It was not, I gained weight, mostly muscle, but my waist did not shrink.
Then last January, I decided to try the "be hungry and ok" technique, and I've done this for about 8 months. My weight has consistently fluctuated in a downward trend. I will never go back to gorging, exercise for weight loss or any of that really stressful stuff, it doesn't work long term for me.
I will start running again soon, and it may help with weight loss, but I won't rely on it. I exercise to be strong and healthy, not to fix my eating problems anymore.
Cheers and encourage to everyone dealing with health and weight issues.