The unfairness issue crops up often among chronic dieters: "It's unfair that everyone gets to eat whatever they want [and only I have to limit myself]." Aside from being erroneous, this sabotaging thought is unhelpful because it leads dieters to feel resentful and deprived and makes it more likely that they will stray from their diet.
But another thought is equally damaging. It occurs when dieters find that they either can't achieve or maintain the amount of weight loss they want. Often they desire to be the same weight as their thinnest friend or family member or a celebrity whose appearance they admire. But few are able to reach this goal. Why? Because to do so they would have to eat in a way that they would be unable to keep up for life. Even if they do get down to as low a weight as they wish, they rarely stay there because they are unable to sustain such a low-calorie level. And as soon as they raise their calorie level, they start to gain weight back.
Their sabotaging thought? "It's so unfair that I can't be as thin as I want." This idea brings them significant emotional pain. Often they are preoccupied by a sense of unfairness. Instead of being proud that they were able to lose and maintain some weight loss, they feel a great injustice. "I worked so hard, and I have to continue to work just to stay at this weight [which is unsatisfactory to me.]" How sad that they feel so negatively, when to lose weight at all is such an accomplishment.
I often say to them, "Yes, you're right. It is unfair, but it seems to me like the greatest unfairness is for you to suffer for even one more day because of this terribly painful idea that you have that you have to be thinner -- an idea that makes you obsess, that makes you unhappy with yourself, that creates a negative frame of mind, that doesn't give you peace with yourself."
I often give them the following analogy: It's like someone who's a good runner who says, "I have to make it to the Olympics." He becomes obsessed with running, he's unhappy with himself, he doesn't have good peace of mind, and so on. Maybe he's a good guy and doesn't deserve to suffer, but he does suffer because he has the realistic expectation that he should be able to make it to the Olympics. And on top of it, instead of accepting the fact that he just isn't built to be a world-class runner, he's preoccupied with the idea that it's unfair, which makes him feel deprived and a little bitter and puts a negative edge on much of his day-to-day experience.
Of course, there is lots more we talk about in terms of fairness. (For example, by and large, many dieters have unfairly positive lives compared to many other people in the world.) But this initial discussion, which implies that dieters have some control over their suffering, via their thinking, is an important start.