Psychological flexibility is not a single dimension: The distinctive flexibility profiles of underweight, overweight, and obese people

Psychological flexibility interventions such as Acceptance and Commitment Therapy have been shown to be beneficial for weight management. Flexibility is often treated as a single, global construct, but it can also be described in terms of interrelated components (e.g., accepting, awareness, defusion, values). Are some components of flexibility of greater relevance to weight-related issues than others? We utilized a planned missing data design to assess weight status and a broad range of psychological flexibility components in a nationally representative sample of Americans (N=7884; 3748 males, 4136 females; age: M=47.9, SD=16). Profile analyses revealed that different weight and gender groups showed different configurations of inflexibility. Underweight men showed a “defensive but active” pattern, expressing high avoidance on multiple dimensions, high levels of fusion, but also showing high hope and willingness to experience distress when pursuing goals. Overweight and obese participants did not show elevated levels of inflexibility, and indeed there was some evidence that overweight men (but not obese and severely obese men) were more flexible than other males. Severely obese participants showed elevated patterns of inflexibility across multiple indices, but this pattern differed for men and women. We conclude that psychological flexibility should not be treated as a unitary construct, and make specific suggestions for future intervention research.