Most of the others have covered the complex stuff so I’ll stick with the basics.
“Willpower” is not a total crock as you need to establish some basis for self discipline in your eating and knowledge of what you’re eating , but it’s a useless conceit if you think WILLPOWER is the main road to losing weight successfully, it’s not, your appetite will aways win.
You need to remember that concept, because no matter how you fight it - Your appetite will always win if you are hungry. You will never dominate your appetite, you can only satisfy it. Losing weight is all about appetite control and how you satisfy it .
So what to do if you want to lose weight and keep it off?
First, and this part involves work not will power. It can be fun or tedious, but it has to be done. You have to count calories in some fashion. Some diet programs like Weight Watchers make this easier with various “selection A+B” methods of portion control, but most successful dieters just record what they eat and the calories involved directly. For food made from scratch you’ll need a small calorie guide to make estimates, and after a month or two the calorie guidelines will mostly all be in your head and you can leave the book home. You can keep a running total in your head or enter it all at the end of the day. I just use a word processor document to keep a daily list of food and calories consumed and start a new one every 3 months when the doc starts getting lengthy. You can use a book dairy or whatever other method works for you, but the key is that if you need to lose some serious weight (10’s of pounds or more) you’ve got to keep a record of what you eat.
In gauging required calories you first need to answer the question of "How much do I need to eat to maintain, gain or lose weight? There are a number of purported metabolic requirement calorie calculators on the web, and they are mostly useless. This one is by far the most accurate and scientifically sound metabolic requirements calculator I’ve found, and will tell you what you can afford to consume in the way of calories with a high degree of accuracy.
As a side note, and something not a lot of people realize, is that planned physical exercise is not really necessary in this context with respect to losing weight, and excuses that “I’m not strong or well enough to exercise so I can’t lose weight” are really sort of silly, and a bit pathetic. Exercise is good and useful and should be a main component of a healthy lifestyle, but with respect to losing weight the amount of body fat burned due directly to exercise over and above the metabolic needs of a sedentary lifestyle is generally relatively small in comparison to the calories burned in the human body that are expended simply in keeping your body temperature around 98 degrees or so. If you look at the number of additional calories burned (vs being sedentary) by moderate levels of exercise it’s remarkably small unless you’re involved in fairly intensive levels of exercise.
So, exercise is very good for you and you should exercise if you can, but planned exercise is NOT necessary to lose weight, and if you are morbidly obese or prone to injury saying you can’t lose weight because you can’t exercise is just silly. What goes into your mouth is the main determinant of your weight not the number of crunches you can do or the miles you walk.
Once you have this number range of required calories you can construct a daily diet around it.
And here is the core concept and where most of the work in dieting is involved.
You can eat whatever you wish, whenever you wish, however you wish, but when you get to your approximate calorie limit you stop. You Just Stop. The commonsense goal is allocating your calories across the day in an a way that satisfies your appetite meal to meal. So the main question then becomes "How can I prepare, or manage to have, tasty, satisfying low calorie, healthy foods and snacks available to me all the live long day? Unless you have a personal dietitian and cook like Oprah the answer is “grunt work and preparation”.
You need to shop for low fat meats, salads, crackers instead of breads, vegetables etc. etc. etc. Stuff you like and can make a meal or a lunch around that will be filling enough to be satisfying so “willpower” is unnecessary. And I’m going to be brutally honest here, if you’re unable or unwilling to commit to the shopping, preparation, storage and overall effort of making tasty low calorie food available to you then you really are just fucking around, and your desire to lose weight is not as great as your desire for convenience.
The issue isn’t “willpower” it’s simply personal choice, and if the value of being less heavy isn’t (to you) worth the grunt work and prep involved in getting your food options arranged, then that’s ultimately your choice. And for a considerable time that was the dysfunctional choice I made, and it’s the choice lots of people make every day. In the end it’s not willpower or some grinding commitment to exercise, it’s simply the willingness to spend the time and effort shopping and stocking and preparing to have good foods ready to eat when you are hungry and that’s the bottom line for long term weight control.
An overweight person with a large appetite, who is disinclined to exercise can still make choices about what they eat and lose lots of weight. If you refuse to get involved in surrounding your lifestyle with healthy, satisfying choices that control your appetite then surgery is probably your only hope.