Diabetes has become a worldwide epidemic: the estimated global prevalence was 2,8% in 2000 and is expected to rise up to 4,4% in 2030. In the year 2000 the excess global mortality attributable to diabetes was 5,2% making diabetes the fifth leading cause of death . The increase in prevalence is associated with aging of the population, the increasing prevalence of obesity in combination with physical inactivity. Cardiovascular disease is the major cause of death among patients with diabetes. An intensive pharmaceutical and behavioral therapy treatment has been estimated to reduce the risk of cardiovascular and micro vascular events by approximately 50% .
Approximately 80% of the people with type 2 diabetes are overweight. Losing weight is the cornerstone of prevention and treatment of type 2 diabetes: it decreases the resistance to insulin, improves glycaemic control and reduces hypertension and lipid abnormalities [3–5]. Weight loss interventions thus may contribute to a reduction of cardiovascular risk and is shown to reduce mortality in patients with type 2 diabetes and obesity .
Unfortunately, interventions aimed at weight reduction have only a limited effect in the long run because of regain of the initial weight loss. The required long-term lifestyle change seems difficult to achieve . A meta-analysis of weight loss interventions in adults with type 2 diabetes showed that multi-component interventions including Very Low Calorie Diets may hold promise for achieving weight loss [7, 8]. However, trials with long follow-up periods are lacking and the most effective type of psychological intervention remains unclear.
In the present study, we determine the effect of an integrated multi-model cognitive group therapy, in obtaining and maintaining favourable effects on weight and cardiovascular risk profile during 2 years of follow-up after a Very Low Calorie Diet.
Very Low calorie diet
A Very Low Calorie Diet (VLCD) is a diet of less than 800 kilocalories (kcal) daily . The very low intake of fat and carbohydrates, but normal amount of proteins (0,8 g/kg ideal bodyweight per day) enhances lipolysis and ketosis while preventing a negative nitrogen balance, sparing lean body mass .
The most commonly used VLCD’s are commercially available mixed-formula diets, containing various amounts of carbohydrate, fat and high quality protein, and have proven safety for use in patients with type 2 diabetes [9, 10].
The short-term effects (i.e. < 6 months) of a VLCD in overweight patients with type 2 diabetes are favourable on weight, glycaemic control, hypertension and dyslipidaemia [11–15]. However, study outcomes are less positive in the long term (i.e. > 1 year follow-up): patients regain most of the lost weight and HbA1c returns to the same value as prior to the intervention. Nonetheless, participants often needed less anti-diabetic agents [16–18]. The study of Jazet, et al.  seems to be a positive exception: 18 months after a 30-day VLCD period, favourable effects on weight, blood pressure and dyslipidaemia were maintained in 18 obese patients with diabetes type 2, but with no effect on HbA1c. The authors indicated that the success was based on the strong motivation of the patients to prevent a need for insulin and a slow reintroduction of normal diet. Limitations of this study, however, were the small intervention group and the lack of a control group.
Taken together, randomized controlled trials of sufficient duration focused on prevention of weight gain after a VLCD in DM type 2 patients are required to improve the effectiveness of VLCDs.
To achieve weight maintenance after successful weight loss, a permanent behaviour change is needed. For this purpose, a variety of psychological interventions have been implemented in weight reduction programmes. Behaviour therapy and cognitive behaviour therapy (CBT) are potential psychological interventions facilitating better maintenance of weight loss . CBT is used to describe a wide range of techniques to change thinking patterns and behaviours. As a result, interventions are heterogeneous and the findings are difficult to compare.
We identified three promising psychological interventions to attain better results in sustaining weight loss: cognitive (behaviour) therapy, problem solving therapy and proactive coping. In the current study, we propose to combine them into an integrated weight maintenance programme.
Cognitive behaviour therapy
Within cognitive psychology, humans are regarded as information processing systems, where knowledge is organized in so-called schemas. Cognitive schemas are activated by incoming information, leading to cognitions (thoughts), emotions and subsequently to behaviour. According to the founding father of the cognitive therapy, Aaron Beck, emotional disorders such as depression and anxiety disorders result from dysfunctional schemas. Cognitive therapy focuses on changing dysfunctional schemas and cognitions, using behavioral experiments and challenges . In eating disorders, the cognitive model was first used to treat bulimia nervosa by adjusting overvaluation of weight and shape based on low self-esteem [22, 23]. In the treatment of obesity, this model is combined with the cognitive model for addiction, which is based on the assumption that addictive behaviour is enhanced by dysfunctional cognitions during exposure to external stimuli like the smell or sight of food .
In a Cochrane review  concerning the effect of psychological interventions in the treatment of overweight and obese patients, positive effects of cognitive behaviour treatment on weight loss were described, particularly when combined with diet and/or physical activity. In a number of studies, weight loss was enhanced significantly by the addition of the cognitive component to an intervention of diet and/or exercise [25–28]. Moreover, it was found that a longer duration of the intervention and more frequent clinical contact was associated with an increased effect. However, studies with substantial follow-up (i.e. > 1 year) are lacking.
In patients with type 2 diabetes, psychotherapy (especially CBT) improves glycaemic control (HbA1c −1,0%) and psychological well-being . Surprisingly, CBT did not appear to affect weight control in this patient group. Perhaps this was caused by too short duration of the studies (i.e. <6 months), as CBT may encourage long-term behavioral changes .
Problem solving therapy
Problem Solving Therapy (PST) is defined as the self-directed cognitive-behavioral process by which a person attempts to identify effective or adaptive solutions for specific problems encountered in everyday living [30, 31]. PST is recognized as an effective treatment of depression [32, 33]. The problem-solving model for obesity treatment was first described by Perri, Nezu and Viegener in 1992  and proposes that active problem solving efforts by a health care provider can help the obese person encounter everyday problems in their weight management. Perri, et al. found significantly greater long-term weight reductions in participants, who completed a PST-intervention, compared to participants receiving behavioral therapy . Moreover, a recent study showed that people with better problem-solving skills lost more weight and were more compliant to therapy .
Proactive coping (PC), directed at an upcoming instead of an ongoing stressor, is a new focus in positive psychology research. PC consists of efforts undertaken in advance of a potentially stressful event to prevent it or modify its form before it occurs. The theory described by Aspinwall and Taylor consists of five stages: PC starts with the ‘accumulation of resources’ such as time, money, planning or organizational skills and social support, so that one is prepared as much as possible to deal with future threats. ‘Recognition’ refers to the ability to see a potential stressful event coming, followed by ‘initial appraisal’ (what is this and should I be worried about this?). The next stage consists of ‘initial coping efforts’: activities undertaken to prevent or minimize a recognized or suspected stressor. Finally, the ‘use of feedback’ involves the evaluation of the stressful event itself and the effects of one’s preliminary efforts .
Schwarzer and Taubert described PC as a way of aspiring a positive future by accumulating resources and realistic goal setting . A recent publication has shown that the pursuit of goals was related to improved wellbeing, while preventing a negative future was not .
A study of the effects of PC on the self-care behaviours of newly diagnosed DM patients revealed that the treatment was highly appreciated and even after 9 months improvements in eating and exercising habits were seen. In addition, the intervention was effective in reducing both weight and blood pressure after 9 months, but had no effect on HbA1c or lipid profile .
In the current randomized study, we compare the effect of a Combined Psychological Intervention (CPI) with usual care on weight maintenance after a Very Low Calorie Diet. Hence, we do not compare the effectiveness of Cognitive Behaviour Therapy with neither Problem Solving Therapy nor Proactive Coping, but combine these three therapies into an integrated multi-model program.
The primary objective of this study is to determine if an integrated multi-model cognitive group therapy, is more effective in preventing weight regain after a Very Low Calorie Diet compared to usual care.
The secondary objectives are to investigate whether an integrated multi-model cognitive group therapy following a VLCD has an effect on glycaemic control, cardiovascular risk profile, psychological variables and quality of life, and subsequently to determine which patient group benefits most of the intervention.
The tertiary objective is to determine whether the intervention is cost-effective.
This research is approved by the Medical Ethics Committee of the Erasmus Medical Centre in Rotterdam (reference number MEC-2009-143/NL26508.078.09), in compliance with the Helsinki Declaration.