Is losing weight a matter of willpower? Why this may be a big lie

Aim of the study: Many self-directed weight-loss interventions have been developed using a variety of delivery formats (e.g., internet and smartphone) and change techniques. Yet, little research has examined whether self-directed interventions can exclusively promote weight loss.

Results: Twenty-seven trials incorporating 36 comparisons met our inclusion criteria. Participants using self-directed interventions lost significantly more weight (MD = -1.56 kg, CI -2.25, -0.86 ranging from 0.6 to 5.3 kg) compared to those in the minimal intervention or no-treatment groups (3.1-month follow-up median). The majority of interventions were internet based (18 evaluations) and these were effective at 3 months (MD = -1.74 kg, CI -2.65, -0.82 ranging from 0.6 to 4.8 kg) (SMD = -0.48, 95% CI -0.72, -0.24, I(2) = 82%; p < .0001; 16 evaluations) and 6 months follow-up (MD = -2.71 kg, CI -4.03, -1.39 ranging from 2.2 to 5.3 kg) (SMD = -0.59, 95% CI -0.99, -0.19, I(2) = 76%; p = .004; 4 evaluations). Self-directed weight-loss interventions can generate modest weight loss for up to 6 months but may need to be supplemented by other interventions to achieve sustained and clinically meaningful weight loss.

Aim of the study: There is a large variability between individuals in the weight loss response to any given diet treatment, which fuels interest into personalized or precision nutrition. Although most efforts are directed toward identifying biological or metabolic factors, several behavioral and psychological factors can also be responsible for some of this interindividual variability.

Results: There are many factors that can influence the response to dietary weight loss interventions, including factors related to eating behavior (emotional eating, disinhibition, restraint, perceived stress), behaviors and societal norms related to age and sex, psychological and personal factors (motivation, self-efficacy, locus of control, self-concept), and major life events. The success of a weight loss intervention can be influenced by many psychological and behavioral constructs and not merely by physiological factors such as biology and genetics. These factors are difficult to capture accurately and are often overlooked. Future weight loss studies should consider assessing such factors to better understand the underlying reasons for the large interindividual variability to weight loss therapy.

Aim of the study: Social support is believed to contribute to weight loss success, yet the type of support received is rarely assessed. To develop more effective weight loss interventions, examinations of the types of support that are associated with positive outcomes are needed. Self-Determination Theory suggests that support for an individual's autonomy is beneficial and facilitates internalization of autonomous self-regulation.

Results: Baseline AS and ASR did not predict outcomes; however, AS and ASR at 6 months positively predicted 18-month weight losses (ps < .05), encouragement of healthy eating at 6 months was negatively related to 18-month weight losses (p < .01), and other forms of directive support were not associated with outcomes. Autonomy support predicted better weight loss outcomes while some forms of directive support hindered progress. Weight loss trials are needed to determine whether family members and friends can be trained to provide autonomy support and whether this is more effective than programs targeting more general or directive forms of support.

Aim of the study: Weight management requires resisting immediate temptations in one's environment (self-control) as well as the ability to persevere towards one's long-term goals despite minor setbacks (grit). This study sought to establish relationships between self-control, grit, and behavioral and health outcomes in the context of a couples-based weight management intervention.

Results: Baseline self-control, changes in self-control, and baseline grit were also associated with 6-month exercise automaticity. Only baseline grit was associated with weight loss maintenance. No partner effects were observed. Findings suggest that self-control and grit are malleable constructs that may play an important role in health behavior habits associated with weight management.ClinicalTrials.gov: NCT02570009, October, 7, 2015.

Aim of the study: To update the recent findings on the influence of personality features on postoperative weight loss in patients undergoing bariatric surgery.

Results: Several studies investigated the influence of pre-surgical psychological variables on the outcome of bariatric surgery, but the effective role of personality factors (i.e., both normal personality traits and personality disturbances) in shaping bariatric surgery outcome is still unclear. We analyzed nine recent papers that examined the impact of pre-operative personality traits on postoperative weight loss among individuals undergoing surgery for severe obesity. A personality pattern denoting the ability to self-regulate in spite of the urges or demands of the moment emerged as a robust predictor of good outcome across studies, independently from baseline psychiatric comorbidity and personality disorders.

Aim of the study: There is a general perception that almost no one succeeds in long-term maintenance of weight loss. However, research has shown that approximately 20% of overweight individuals are successful at long-term weight loss when defined as losing at least 10% of initial body weight and maintaining the loss for at least 1 y.

Results: To maintain their weight loss, members report engaging in high levels of physical activity ( approximately 1 h/d), eating a low-calorie, low-fat diet, eating breakfast regularly, self-monitoring weight, and maintaining a consistent eating pattern across weekdays and weekends. Moreover, weight loss maintenance may get easier over time; after individuals have successfully maintained their weight loss for 2-5 y, the chance of longer-term success greatly increases. Continued adherence to diet and exercise strategies, low levels of depression and disinhibition, and medical triggers for weight loss are also associated with long-term success. National Weight Control Registry members provide evidence that long-term weight loss maintenance is possible and help identify the specific approaches associated with long-term success.

Aim of the study: Drawing upon firsthand accounts of GLP-1RA weight-loss drugs, this paper challenges the bioconservative view that effort is essential to self-control and the narrower view that obesity is simply a matter of weakness of will. Many dieters have persistent intrusive food thoughts that are neither transparent nor voluntarily controllable.

Results: Many dieters have persistent intrusive food thoughts that are neither transparent nor voluntarily controllable. By quieting food noise, these drugs offer users epistemic access to the true target of effective self-control and provide a pathway to long-term success that effort alone rarely secures. We argue that the value of self-control lies not in the subjective experience of struggle but in the skillful alignment of behavior with one's goals. "Effortless" self-control, far from being a cheat, can exemplify precisely what is valuable about agency.

Aim of the study: Behavioral obesity treatments are associated with early weight loss; however, participants typically begin to regain the weight within several months as their self-efficacy to control eating (SEce) often diminishes after they begin to better realize associated challenges. Therefore, authors of this article aimed to discern psychosocial predictors of such reductions.

Results: There was no significant time × treatment type effect. Within multiple regression analyses, each of those correlates, except dejection, significantly contributed to the explained variance in SEce change (p < .001). Participants' change in SEce from baseline to Month 6 was a significant predictor of their six-, 12-, and 24-month weight changes (ps < .001). These findings suggest psychosocial targets for addressing decreases in SEce and subsequent regains in weight that can follow.

Aim of the study: To evaluate engagement and weight loss with a 12-month total diet replacement (TDR) programme in women with increased risk of breast and endometrial cancer, living with obesity.

Results: 37 women (79%) completed the whole programme. Completers and those who withdrew, respectively, had a mean (SD) age of 41.4 years (5.7) vs 38.1 (5.8) and baseline body mass index of 36.2 (4.9) kg/m2 vs 40.0 (7.9) kg/m2 and 76% vs 90% had children 18 or younger living at home. Median (IQR) weight was reduced at all time points; -10.8 kg (-13.8, -7.2) at 3 months, -11.5 kg (-15, -7.6) at 6 months, -11.0 kg (-16.4, -7.8) at 9 months and -8.4 kg (-13.9, -3.7) at 12 months. Across the 12-month programme, the median (IQR) contacts with the study dietitians per participant was 28 (25, 33) and median contact hours were 7.6 (6.6, 10.6). 68% received psychological support. QOL improved; OWL-QOL (Obesity and Weight Loss)-17 (-24.8, -7.8) and EQ5D 1 (0, 2), with reductions in binge eating scores -4 (-6.5, -0.8) but no changes in mental health or physical activity scales. TDR could be a weight loss programme for women at increased risk of breast and endometrial cancers related to obesity.

Aim of the study: Sustained weight loss requires a persistent reduction in energy intake combined with increased energy expenditure. Assessment of such strategies can improve treatment outcomes. The National Weight Control Registry (NWCR) has identified behavioral approaches associated with successful long-term weight loss maintenance.

Results: Participants achieving ≥ 15% WL more frequently reported reduced energy intake, reduced fat and sugar consumption, and regular physical activity at both 6 and 12 months compared with those achieving < 5% WL (all p < 0.03). Individuals in the ≥ 15% WL group reported a greater number of successful strategies at both time points (p < 0.001). These findings from a clinical setting largely corroborate previous registry-based evidence, demonstrating that clinically significant weight loss achieved during structured obesity treatment is associated with more frequent reporting of behaviors identified by the National Weight Control Registry.