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Background: Lifestyle interventions can prevent type 2 diabetes (T2D) by successfully inducing behavioral changes (eg, avoiding physical inactivity and sedentariness, increasing physical activity and/or healthy eating) that reduce body weight and normalize metabolic levels (eg, HbA1c). For interventions to be successful, it is important to influence "behavioral mechanisms" such as self-efficacy, which motivate behavioral changes. Theory-based expectations of how self-efficacy, chronic stress, and mood changed over time were investigated through a group-based behavior change intervention (PREMIT). At 8 intervention sites, PREMIT was offered by trained primary care providers in 18 group-sessions over a period of 36 months, divided into 4 intervention phases. Adherence to the intervention protocol was assessed., Method: Participants (n = 962) with overweight and prediabetes who had achieved ≥8% weight loss during a diet reduction period and completed the intervention were categorized into 3 groups: infrequent, frequent, or very frequent group sessions attendance. The interactions between participation in the group sessions and changes in self-efficacy, stress, and mood were multivariate tested. Intervention sites were regularly asked where and how they deviated from the intervention protocol., Results: There was no increase in the participants' self-efficacy in any group. However, the level of self-efficacy was maintained among those who attended the group sessions frequently, while it decreased in the other groups. For all participants, chronic stress and the frequency of attending group sessions were inversely related. Significant differences in mood were found for all groups. All intervention centers reported specific activities, additional to intervention protocol, to promote participation in the group sessions., Conclusions: The results suggest that the behavioral changes sought by trained primary care providers are related to attendance frequency and follow complex trajectories. The findings also suggest that group-based interventions in naturalistic primary care settings aimed at preventing T2D require formats and strategies that encourage participants to attend group sessions regularly., Competing Interests: Declaration of Conflicting InterestsThe author(s) declared the following potential conflicts of interest with respect to the research, authorship, and/or publication of this article: Anne Raben has received honorariums from Nestlé, the International Sweeteners Association and Unilever. Pia Siig Vestentoft has received travel grants from the Cambridge Weight Plan, UK. Ian Macdonald was a member of the UK Government Scientific Advisory Committee on Nutrition, Treasurer of the Federation of European Nutrition Societies, Treasurer of the World Obesity Federation, member of the Mars Scientific Advisory Council, member of the Mars Europe Nutrition Advisory Board and Scientific Adviser to the Waltham Centre for Pet Nutrition. He was also a member of the Nestle Research Scientific Advisory Board and of the Novozymes Scientific Advisory Board. Jennie Brand-Miller is President and Director of the Glycemic Index Foundation, oversees a glycaemic index testing service at the University of Sydney and is a co-author of books about diet and diabetes. Sally Poppitt was the Fonterra Chair in Human Nutrition and Principle Investigator for NZ National Science Challenge High Value Nutrition during the PREVIEW intervention. Thomas Meinert Larsen is advisor for the “Sense” diet program. J. Alfredo Martinez is President of IUNS. All other authors have no conflicts of interest to declare.

Aims/hypothesis: Lifestyle interventions are the first-line treatment option for body weight and cardiometabolic health management. However, whether age groups or women and men respond differently to lifestyle interventions is under debate. We aimed to examine age- and sex-specific effects of a low-energy diet (LED) followed by a long-term lifestyle intervention on body weight, body composition and cardiometabolic health markers in adults with prediabetes (i.e. impaired fasting glucose and/or impaired glucose tolerance)., Methods: This observational study used longitudinal data from 2223 overweight participants with prediabetes in the multicentre diabetes prevention study PREVIEW. The participants underwent a LED-induced rapid weight loss (WL) period followed by a 3 year lifestyle-based weight maintenance (WM) intervention. Changes in outcomes of interest in prespecified age (younger: 25-45 years; middle-aged: 46-54 years; older: 55-70 years) or sex (women and men) groups were compared., Results: In total, 783 younger, 319 middle-aged and 1121 older adults and 1503 women and 720 men were included in the analysis. In the available case and complete case analyses, multivariable-adjusted linear mixed models showed that younger and older adults had similar weight loss after the LED, whereas older adults had greater sustained weight loss after the WM intervention (adjusted difference for older vs younger adults -1.25% [95% CI -1.92, -0.58], p<0.001). After the WM intervention, older adults lost more fat-free mass and bone mass and had smaller improvements in 2 h plasma glucose (adjusted difference for older vs younger adults 0.65 mmol/l [95% CI 0.50, 0.80], p<0.001) and systolic blood pressure (adjusted difference for older vs younger adults 2.57 mmHg [95% CI 1.37, 3.77], p<0.001) than younger adults. Older adults had smaller decreases in fasting and 2 h glucose, HbA 1c and systolic blood pressure after the WM intervention than middle-aged adults. In the complete case analysis, the above-mentioned differences between middle-aged and older adults disappeared, but the direction of the effect size did not change. After the WL period, compared with men, women had less weight loss (adjusted difference for women vs men 1.78% [95% CI 1.12, 2.43], p<0.001) with greater fat-free mass and bone mass loss and smaller improvements in HbA 1c , LDL-cholesterol and diastolic blood pressure. After the WM intervention, women had greater fat-free mass and bone mass loss and smaller improvements in HbA 1c and LDL-cholesterol, while they had greater improvements in fasting glucose, triacylglycerol (adjusted difference for women vs men -0.08 mmol/l [-0.11, -0.04], p<0.001) and HDL-cholesterol., Conclusions/interpretation: Older adults benefited less from a lifestyle intervention in relation to body composition and cardiometabolic health markers than younger adults, despite greater sustained weight loss. Women benefited less from a LED followed by a lifestyle intervention in relation to body weight and body composition than men. Future interventions targeting older adults or women should take prevention of fat-free mass and bone mass loss into consideration., Clinical Trial Registration Number: ClinicalTrials.gov NCT01777893., (© 2022. The Author(s).)

Introduction: Changing lifestyle habits to achieve and maintain weight loss can be effective in prevention of Type II diabetes. Ability to resist temptations is considered one of the key factors in behavior change. This study examined how habit strength, motivation, and temptations for an energy-dense diet developed during the maintenance stage of a behavior modification intervention tool., Method: Participants with prediabetes and overweight/obesity were recruited in the two-phase trial PREVIEW with the aim to achieve ≥ 8% body weight loss over 2 months and maintain weight loss over a subsequent 34-month period. The four-stage intervention (PREVIEW Behavior Modification Intervention Toolbox, or PREMIT) supported participants in weight maintenance. Uni- and multivariate analyses were completed from the beginning of the PREMIT maintenance stage (Week 26 of the PREVIEW trial) with 962 individuals who completed the trial., Results: Habit strength and ability to resist temptations increased during the early PREMIT adherence stage (Weeks 26 to 52) before plateauing during middle (Weeks 52 to 104) and late (Weeks 104 to 156) PREMIT adherence stages. Higher habit strength for energy-dense diet was significantly associated with larger weight regain ( p ≤ .007). No changes in motivation or interactions with PREMIT attendance were observed., Discussion: Changing diet habits is a complex, multifactorial process, with participants struggling at least with some aspects of weight maintenance. Habits against consuming energy-dense, sweet, and fatty food appeared effective in protecting against weight regain. The observed effect sizes were small, reflecting the complexity of breaking old habits and forming new ones to support long-term maintenance of weight loss. (PsycInfo Database Record (c) 2022 APA, all rights reserved).