Obesity and overweight are growing steadily and becoming a global epidemic. Recent researches report a 64% of the adult population as overweight. The social and economical impact is increasing and the most of the rehabilitation programs, while effective in the short term, do not produce long lasting results. From a behavioral perspective an explanatory model can describe the phenomena with the lack of sources of reinforcement related to healthy habits in the daily-life context. The goal of this project, combining Acceptance and Commitment Therapy and Wearable Technology, is to develop an effective intervention, efficient and sustainable, which continues after ending of the hospitalization, providing adequate contingencies of reinforcement in the natural environment, integrating systematic measurements, continuous feedbacks and individualized, values-based objectives. Related goal-setting show a shift from results linked with weight loss towards action connected with healthy life-style.

Background The condition of being overweight is an increasing problem worldwide, becoming an epidemic both in Europe and in the United States. Recent estimates that over 60% of adults are overweight and at the same time obesity affects around 35% of the population. In the US the cost of the health system to cope with obesity and related diseases now exceeds the sum of 100 billion and in Europe costs are currently similar. Health risks related to being overweight include psychological difficulties, depression and stigma, physical problems and heart diseases, cancer and respiratory diseases not to mention musculoskeletal and metabolic problems.

Obesity is a chronic health condition, but is also a major risk factor for various diseases both chronic and acute. This problem is currently steadily rising, with prevalence data and epidemiological estimates that should be of great concern. Despite strong biological components and hereditary aspects, obesity is primarily linked to incorrect habits of everyday life, mainly eating habits and physical activity. Numerous studies have documented that regular physical activity and wise choices in food uptake can prevent obesity and related conditions.

The main challenge in addressing obesity and associated disorders is represented by developing and making available and sustainable comprehensive programs that include combinations of physical activity, dietary aspects and psychological interventions.

Interventions developed in this way, including dietary education protocols, physical rehabilitation and exercises programs, nutritional, endocrinological, psychological, surgical and pharmacological treatments are mainly effective in the short term, despite many of which are characterized by high costs and several periods of hospitalization. The analysis of the literature suggests the superiority of intensive multidisciplinary interventions: health protocols, dietary programs, psychological and physical rehabilitation. One of the problems of such interventions is that they are often only possible during an hospitalization period, with high costs associated. However, despite good evidence of effectiveness, the long-term results are generally limited.

In general, availability, costs, compliance and long-term efficacy are important limitations to this variety of approaches. Frequently obese individuals regain about 30% of the weight they lost within the first year. After only 3 years they are returning to pre-treatment weight. Psychological intervention are generally assumed to be one of the core parts in the treatment aimed to obesity. In particular, Cognitive-Behavioral interventions, usually within multidisciplinary paths and rarely implemented individually, are generally considered the gold-standard for addressing the epidemic of obesity, or "globesity".

Rationale Reasons for the long-term failure of interventions for obesity can be found in the lack of long-term sources of reinforcement for healthy habits acquired during the intensive treatment period. The tradition of behavioral sciences has developed models of interpretation, explanation and pragmatic operation supported by evidence of effectiveness and efficiency in the promotion of desired behaviors in various contexts and with a longer time effect. These span from the cessation of smoking, passing trough the ability to adapt and live with chronic diseases, ending with the promotion of safety behaviors in working environments. For this reason behavior analysis in general, and in particular the Contextual Behavioral Science, can play a decisive role in the prevention of obesity and keeping the results achieved within short intensive protocols, usually held in hospitals.

By modifying deeply rooted and long-term acquired habits, the person with obesity can obtain more psychological and physical health, reduce risk factors and improve his overall health, wellness and quality of life with benefits not only for the individual but also for his social environment.

During the rehabilitation periods patients affected by obesity are frequently in contact with contingencies that are very different from those of their daily lives. In the rehabilitation facility or during the hospitalization, contingencies are efficiently shaped to promote desired behaviors and decrease actions that are identified as dysfunctional, with both aversive and reinforcing contingencies. Later on, after the treatment, in his natural environment initially behaviors are maintained, but having been promoted in a environment that provide contingencies supporting healthy behaviors, they often undergo a processes of extinction consequently with cessation of reinforce. At the same time, outside the hospital, dysfunctional behaviors such as avoiding physical activity and eating tasty food, are reinforced in a systematic and contingent way. This tendency to extinction of functional and healthy habits and reinforcement of dysfunctional habits leads, in the long term to gain the weight lost laboriously and this also leads to lower levels of well-being.

Although the existing programs already provide protocol phases to be implemented once they are home, often the patients fail to adhere to nutrition programs and planned activities. On the contrary they return frequently to previous habits, and show a high drop-out rate at follow-ups.

To overcome the limited long-term adherence after the hospitalization period, it is necessary to find a way to give significant, contingent and informative feedback also after the rehabilitation phase. In this regard the use of activity trackers represents a clear, valid and "smart" use of new technologies, linked to well established behavioral science.

Hypothesis, goals and expected results The project aims to promote a long-term change in lifestyle of as part of a multidisciplinary intervention, in close collaboration with physicians, the service of Clinical Nutrition and the osteo-articular rehabilitation.

The main goal of this study is test the efficacy of combining behavioral change technologies through contingent and meaningful feedbacks provided by wearable devices with ACT-based intervention, a well-studied psychological treatment developed in a contextual behavioral framework. The combination of thisapproach should be feasible and efficient, compared with gold standard treatment with inferior costs. Four experimental condition are provided: 1) usual care during hospitalization with programmed follow-up checks, 2) contingent feedback on daily life activities through activity trackers or wearable device stand-alone, 3) ACT based intervention stand-alone, 4). combination of the previous two, ACT-Based Intervention and Activity Tracker with Feedback.

Primary outcome, or dependent variable, of the study is physical activity as collected by wearable electronic devices. Other outcomes, as for example time of sleep, are collected by wearables, and other provided by self report through web platform. The independent variable of the study is the type of treatment (ACT intervention and feedbacks provided by activity trackers). For the purpose of the study we collect data about daily steps and workout log for each participants.

The intervention aims to help people in their everyday environment to remain more consistent with the choices made, and follow appropriate diets and physical activity. The project is directed to participants in the multidisciplinary rehabilitation program at St. Joseph Hospital - Verbania, Italian Auxological Institute, a private research institute that works also for the Italian national health system. The recruitment will take place progressively and subjects will be randomized to the four experimental conditions expected by the protocol. Data will be analyzed in different experimental single-subjects over multiple baselines designs. The subjects are also grouped according to the experimental condition to allow statistical analysis of experimental designs intergroup, consistent with the approach of a controlled and randomized trial.

Due to the novelty of using a combination of behavioral change strategies with Acceptance and Mindfulness - based therapy with wearable device to promote healthy life-style in the post-rehabilitation period, no well defined hypothesis have been established about the possible contribution of this kind of intervention in comparison with usual care, the "gold standard" multi-disciplinary treatment chronic conditions linked to obesity. With the development of mobile technology and brief clinical protocols, new interventions in the field of obesity and connected chronic pathologies have to be evaluated.

Anyway, the mACTonHEALTH study is quite innovative for different reasons. First, combination of single case designs with RCT is uncommon, particularly with medium-scale studies like this. Second, using wearable device activity trackers both as device for data collection measuring the primary outcomes and as device to provide contingent feedbacks, assumed to as one the two independent variable. Third, combining directly brief ACT intervention and behavior modification strategies with mobile-tech implementation is another element of innovation. Furthermore, although ACT is becoming well-studied in the traditional clinical context, large-scale application to both medical and natural settings has not largely occurred. Including in assessment procedure direct collectable data, indicators of both physical and psychosocial health. Also, the inclusion of objective physiological outcome measures constitutes an aspect of innovation in ACT research. Last, the study will focus on mediation mechanisms underlying treatment success and presents possible links to systematic models on psychological flexibility, a core process assessed in ACT researches.

Hypothesis To the best of the researcher's knowledge, this study will be the first randomized controlled trial to examine the effectiveness of a combination of contingent feedbacks provided with wearable devices with ACT-based interventions to improve healthy life style according to medical and behavioral prescription among obese patients. It is also one of the first example of a large implementation of multiple single case designs with a continuous data collection, made possible due the implementation of wearable-technology. Conducted in the context of clinical practice, this trial will potentially offer empirical support to alternative interventions to improve radical long-time change in life habits and consequently promote quality of life reducing mortality and morbidity rates among obese population. Furthermore, by virtue of its short duration, the program could potentially be utilized for health promotion also in non-hospitalization context and primary or secondary prevention of obesity and linked conditions.

Inclusion Criteria:

• age between 18 and 70 years;
• obesity according to the WHO criteria (BMI ≥ 30); ù
• written and informed consent to participate, 4) tech-friendly to receive feedback through smartphone, mail and wearable devices

Exclusion Criteria:

• other severe psychiatric disturbance diagnosed by DSM-V criteria;
• severe visual difficulties,
• important limitations of movement, in particular subjects for which it is not recommended physical activity,
• concurrent medical condition not related to obesity. DSM-V (Thomas et al., 2014) will be used as screening tools for psychiatric disorders.