Weight loss for someone who is not overweight

This group may be helpful for you: http://community.myfitnesspal.com/en/group/499-not-that-heavy-girls

Whether you want to count calories or not, you need to be in an calorie deficit to lose weight. Counting them is the easiest way to be sure you are in a deficit. Just because you start counting doesn't mean it's something you can't follow for the rest of your life. Counting makes you so aware about the foods you are taking in and you can learn so much about losing AND maintaining your weight this way. If you want to be able to do it for the rest of your life, your best bet is to find a way to fit in the foods you enjoy, and pick a small deficit that you can adhere to. This way, once you have lost the weight, you can just add a few hundred calories back in...you're not drastically changing your diet.

Counting calories can be a lifestyle eating plan. For some people, though, especially people who don't have a disordered/emotional relationship with food but gained weight circumstantially, it can be a useful tool temporarily for getting back in the habit of eating appropriate amounts, and for achieving the kind of deficits needed to lose weight with a small margin of error (which is what you, as an already-normal-weight person, need to achieve).

"Eating healthy" is, for weight loss purposes, essentially meaningless. Regardless of what you eat, you have to create a caloric deficit to lose. You haven't been able to achieve a calorie deficit without counting. That's not surprising in a person who has gained weight- for whatever reason, the balance you were able to achieve before you gained weight is out of whack. You may be able to reset it and not be a calorie counter for life, but the most likely way to re-learn that skill set you once have and loss the weight you've gained is to learn to count calories.

Maybe the actual counting won't have to be a life-long thing for you. But you've pretty much given yourself the answer- you eat what you believe to be healthy diet, and you workout, and you're still not losing weight. So you know you're still eating as many or more calories than you burn.

The quickest way to rectify that situation, regardless of what diet gurus tell you and ESPECIALLY for people who are not overweight, is to count those calories and see where the imbalance lies.

Firstly, set weight point is not a thing. I used to think my set weight was 65kg. I'm currently 57kg.
Secondly, it works the same whether your bmi is obese, overweight, or "healthy". It's just the less you have to lose, the smaller the margin of error, and the slower the loss. You still need a calorie deficit to lose weight, whether you get that via counting calories (probably the most efficient method) or some other way.
If you have been sitting at the same weight for a while, you can safely assume that you're eating at "maintenance" for your size and activity. To create a deficit, you can eat less, move more, or a combination of both. Now, without calorie counting it's going to be difficult to calculate how big your deficit is, and how quickly/slowly your rate of loss is, but if you're not too hung up on that, it shouldn't be a problem. I've lost weight without calorie counting, and maintained the loss until I became pregnancy. I prefer calorie counting as I like the numbers/certainty/accountability, but plenty of people lose without it.
Fwiw I'm not overweight by any means (bmi about 21) and I'm still planning to lose weight. Your goal weight is your goal weight.

I thought the way to lose the "freshman butt" was to become a sophomore ? No ?
Calorie deficit it is then. 20 pounds will require 70,000 calorie deficit, that is a pretty large sum to just wing.
Using MFP to Count them meal by meal and day by day breaks the task down into a manageable task.