Can self-help be bad for you?

From the NHS Behind the Headlines blog:

“Self help makes you feel worse,” BBC News has reported. It says that the growing trend of using self-help mantras to boost your spirits may actually have a detrimental effect. The news comes from Canadian research, which found that people with low self-esteem felt worse after repeating positive statements about themselves.
Although positive self-statements are widely believed to boost mood and self-esteem, they have not been widely studied, and their effectiveness has not been demonstrated. This experimental study sought to investigate the contradictory theory that these statements can be harmful.

The researchers had a theory that when a person feels deficient in some way, making positive self-statements to improve that aspect of their life may highlight the discrepancy between their perceived deficiency and the standard they would like to achieve. The researchers carried out three studies in which they manipulated positive self-statements and examined their effects on mood and self-esteem.

Something about the hypothesis sounds familiar:

This experimental research among a group of Canadian university students has found that positive statements may reinforce that positivity among those with high self-esteem, and make them feel even better. But it causes those with low self-esteem to feel worse and to have lower self-esteem.

The researchers say that this theory is based on the idea of ‘latitudes of acceptance’, i.e. messages that reinforce a position close to one’s own are more likely to be persuasive than messages that reinforce a position far from one’s own. As they suggest, if a person believes that they are unlovable and keeps repeating, “I’m a lovable person”, they may dismiss this statement and possibly reinforce their conviction that they are unlovable.

What do you think? Is this plausible, or is it an attempt to shoehorn one of those trendy heuristics-and-biases-related hypotheses into a study on self-esteem? If you accept the validity of the study and its conclusion, does it influence LW’s Rationalists Should Win self-help philosophy? What if it is literally true that some people are more lovable and some less, and that this has unavoidable effects on self-esteem? Do low self-esteem rationalists need different techniques from those with high self-esteem?