1. There is no one way to lose weight. I read a lot of weight loss blogs, have read a lot of scientific articles, and have a lot of readers of my blog who have talked about their struggles. People lose weight a lot of different ways and it is, in my opinion, individual as to what works for the particular person.
3. The biggest factor that I have seen in successful long term weight loss is commitment to the weight loss and commitment to maintaining. Someone with a short term mentality of wanting to lose weight quickly and then go back to eating how they ate before will usually regain regain.
These are the keys IMO.
We all have a different base metabolic rate, though you can alter your metabolism significantly with your eating and exercise habits. While 5-10% of us will be overweight without a herculean effort, there are lots of folks in developed countries who are unnecessarily overweight or obese.
The most effective way to maintain a healthy weight IME is a combination of mindful eating and exercise.
Your body will find an equilibrium based on what you eat and the exercise/activity you maintain. Anything temporary is a waste of time. Maintaining a healthy weight is an ongoing lifestyle, not a program you follow only to revert to the prior lifestyle that led to unhealthy weight.
That does not mean you have to starve yourself or count calories obsessively - no one will maintain that indefinitely. You can't diet for a while and then revert to poor eating habits, or your weight will revert to what it was before (or worse, the yo-yo effect). Doing Weight Watchers for weeks or months may decrease your weight, but if you revert to your pre-WW eating habits, the weight will quickly come back and then some.
We all know the basic do's and don'ts by now, there's no magic bullet or shortcut. Need to be very conscious of saturated fats, sugars/simple carbs including alcohol. You need a combination of proteins, carbs and (good) fats - excluding any one is not healthy, they all have a purpose. Try to fill up on raw or steamed vegetables and just water, 4-6 ounces of lean protein, and go easy on carbs like potatoes, white rice and lots of processed foods. The calories nutritional info can be found on most foods, and in most restaurants (if you just ask).
I did Body for Life for several years, and those habits are largely still intact. What I found most helpful, was the concept of eating healthy six days/week and then splurging ONE day a week if I want to - literally eating anything I wanted one day a week. Like many, you find you don't want to splurge that often, but if you do, no problem. Or an event comes up where there's just too much temptation, you eat and drink what you want - no problem. The idea that you could splurge once a week makes it a lot easier to maintain a "program" IME. Denying yourself meal after meal, day after day, week after week, etc. - is too much. And it's not necessary...
And it doesn't mean you have to become a triathelete - VERY few will maintain that lifestyle indefinitely. You can't exercise like a madperson and then revert to a sedentary lifestyle, or your weight/fitness will revert to what it was before. It doesn't have to be conventional exercise, just something active, get off the couch! Though some folks want to just maintain good weight by diet alone, that alone does not guarantee good health. Being active is essential to good health, maintaining muscle mass, performing everyday tasks without risk of injury, etc.
You need to find a way to eat in moderation, and stick with it. You need to find exercises or just physical activities that you can stick with. If you splurge on food once a week or less, or miss exercise/activity every few days, it won't kill your body weight/fitness.
