Weight change, psychological well-being, and vitality in adults participating in a cognitive-behavioral weight loss program.

Obesity poses one of the greatest threats to the future of our public health, with over 400 million people worldwide estimated to be obese and 1.6 billion estimated to be overweight (World Health Organization, 2006). Weight loss, while strongly encouraged by health care professionals, remains challenging to achieve and maintain for many living with excess weight. Though the multiple potential benefits of weight loss for obese individuals span medical, social and psychological domains, barriers to losing weight and maintaining reductions in weight remain for much of this population. Furthermore, many individuals living with significant excess weight encounter more health and psychosocial problems, as well as prejudice and discrimination, all of which can lower quality of life (Gregg & Williamson, 2002; Rand & Macgregor, 1990; Wadden, Womble, Stunkard, & Anderson, 2002). The relationship between excess weight and dimensions of both quality of life (QoL) and health-related quality of life (HRQL) has been extensively examined (deZwann, et al, 2009; Han, Tijuis, Lean, & Seidell, 1998). QoL and HRQL assessments typically measure multiple aspects of well being and functioning, including vitality, perceptions of general health, pain, social and physical functioning, impairment or disability, and mental health. Individuals with larger waist circumferences and higher Body Mass Indices (BMI) report lower quality of life and more impairment in completing tasks of everyday living (Han, Tijuis, Lean, & Seidell, 1998). Middle-aged overweight and obese women (BMI > 25 kg/m2) describe lower levels of social functioning and vitality, as well as worse overall mental health, compared to women in the normal weight range (Brown, Dobson, & Mishra, 1998). Additionally, women who perceive themselves as overweight report lower levels of general health, vitality and physical functioning, and women with a history of frequent weight loss displayed notable reductions in scores on the mental health and emotional functioning areas of quality of life measures (Burns, Tijhuis, & Seidell, 2001). Obese individuals may also experience significant levels of chronic pain, particularly back and knee pain, which may reduce perceptions of quality of life (Barofsky, Fontaine, & Cheskin, 1997). As with other serious medical conditions, obesity has been associated with the presence of mental health problems, including depression and anxiety, in women (Carpenter, Hasin, Allison, & Faith, 2000; Jorm, et al., 2007). However, a recent study by de Zwann and colleagues (2009) found BMI to be a significant predictor of negative outcomes regarding the physical dimensions of HRQL (i.e., physical functioning and limitations, physical pain, general health) but not a predictor of negative psychological HRQL outcomes (i.e., social functioning, role limitations due to emotional problems). Physically, weight change impacts multiple facets of health-related quality of life. A large prospective study found that women who gained weight over a four-year period demonstrated decreases in physical functioning and levels of vitality, and reported increased bodily pain (Fine et al., 1999). Conversely, weight loss can result in improvements in quality of life. Women from the same study who lost weight over the four-year period showed improvements in physical functioning and vitality, and decreases in amounts of bodily pain. Additionally, Fontaine and colleagues (1999) found significant increases in health-related quality of life scores following a 13-week weight loss treatment program, including gains in physical functioning, general health, vitality, and mental health. Smoller, Wadden and Stunkard (1987) reviewed the literature on the effects of dieting on mood and found that patients in behaviorally or medically-oriented treatments reported improvements in mood, while obese patients in psychiatric care reliably reported negative changes in mood. Weight loss in individuals living with morbid obesity is associated with reductions in levels of depression (Dixon, Dixon & O’Brien, 2003). HRQL and well-being instruments assess a wide range of quality of life traits, including daily functioning, general health, mental health and notably, vitality, which is defined as, “the specific psychological experience of possessing enthusiasm and spirit” (Ryan & Frederick, 1997, p. 530). Peterson and Seligman (2004) found vitality to have principal components of zest, enthusiasm, vigor, and energy. Structural equation modeling found vitality to measure the subjective feeling of being alive and alert (Bostic, Rubio, & Hood, 2000). Self-determination theory predicts that autonomous motivation would enhance subjective vitality relative to motivation by external control (Nix, Ryan, Manly, & Deci, 1999; Ryan & Deci, 2008). While increases in overall scores on HRQL measures are documented frequently in the literature following weight loss, it is unclear which aspect or aspects of HRQL are responsible for this overall change (i.e., mental health, general health, vitality). In this study, we sought to examine the efficacy of a weight loss intervention on BMI, behavioral change (i.e., calorie intake, exercise levels), cardiovascular risk factors, perceived obstacles to behavior change, and mental health. In this paper, we examined the impact of these interventions on psychological well-being in a cohort of overweight and obese participants. We examined which aspect or aspects of well-being drove improvements in well-being scores in accordance with weight change. Specifically, we hypothesized that reductions in weight would be associated with increases in overall psychological well-being, vitality and general health. Furthermore, in accordance with previous research, we hypothesized that reductions in weight would be associated with lower levels of depression. Finally, we sought to determine if weight change would be associated with changes in levels of anxiety and perceptions of self-control.