The PREVIEW intervention study: Results from a 3‐year randomized 2 x 2 factorial multinational trial investigating the role of protein, glycaemic index and physical activity for prevention of type 2 diabetes

Abstract

Aim To compare the impact of two long‐term weight‐maintenance diets, a high protein (HP) and low glycaemic index (GI) diet versus a moderate protein (MP) and moderate GI diet, combined with either high intensity (HI) or moderate intensity physical activity (PA), on the incidence of type 2 diabetes (T2D) after rapid weight loss. Materials and Methods A 3‐year multicentre randomized trial in eight countries using a 2 x 2 diet‐by‐PA factorial design was conducted. Eight‐week weight reduction was followed by a 3‐year randomized weight‐maintenance phase. In total, 2326 adults (age 25‐70 years, body mass index ≥ 25 kg/m2) with prediabetes were enrolled. The primary endpoint was 3‐year incidence of T2D analysed by diet treatment. Secondary outcomes included glucose, insulin, HbA1c and body weight. Results The total number of T2D cases was 62 and the cumulative incidence rate was 3.1%, with no significant differences between the two diets, PA or their combination. T2D incidence was similar across intervention centres, irrespective of attrition. Significantly fewer participants achieved normoglycaemia in the HP compared with the MP group (P < .0001). At 3 years, normoglycaemia was lowest in HP‐HI (11.9%) compared with the other three groups (20.0%‐21.0%, P < .05). There were no group differences in body weight change (−11% after 8‐week weight reduction; −5% after 3‐year weight maintenance) or in other secondary outcomes. Conclusions Three‐year incidence of T2D was much lower than predicted and did not differ between diets, PA or their combination. Maintaining the target intakes of protein and GI over 3 years was difficult, but the overall protocol combining weight loss, healthy eating and PA was successful in markedly reducing the risk of T2D. This is an important clinically relevant outcome.

A High-Protein, Low Glycemic Index Diet Suppresses Hunger but Not Weight Regain After Weight Loss: Results From a Large, 3-Years Randomized Trial (PREVIEW)

“…Compared with moderate-PA, we found highintensity PA did not make a difference to appetite suppression during WLM. As reported elsewhere (31), there was no difference in vigorous and moderate-to-vigorous PA between the HI and MI groups according to PREVIEW accelerometry data. The lack of PA compliance may be one of the potential reasons why we did not detect any difference in appetite sensations between the two PA groups.…”

“…The heterogeneity in findings can probably be attributed to differences in macronutrient content, but a complicated interplay between other dietary factors can also affect both carbohydrate digestion and metabolism (50) and thereby feelings of appetite. In some studies, fiber content of the test meals was not controlled (51), although fiber intake was similar between the PREVIEW intervention groups according to the food records (31). It should be remembered, however, that we could not separate the potential effects of low GI and higher protein intake in PREVIEW, since they were both included in the HP diet.…”

“…In order to encourage higher levels of compliance and behavior change, PREVIEW developed a program called PREMIT to help participants develop new diet and PA habits (33,54) during the 3-years intervention. Data from food records and accelerometry indicated that during WLM, participants led a healthier lifestyle with higher total volume of PA (31). Nonetheless, it seems that behavioral approaches may not be sufficient for participants with overweight and obesity to achieve high intensity PA over the long term.…”

“…This secondary analysis was based on the data from PREVIEW, a 3-years multi-center, 2 × 2 factorial randomized controlled trial (RCT) conducted at eight intervention centers in Denmark, Finland, the UK, the Netherlands, Spain, Bulgaria, Australia, and New Zealand. Detailed information has been published in the PREVIEW protocol and main papers (29)(30)(31). Briefly, the aim of the PREVIEW study was to explore the effects and interactions of two diets and two PA programs on the prevention of type 2 diabetes.…”

“…The dietary compliance has been reported in the PREVIEW main results paper (31). In brief, from the 4-days food records, the HP-MI and HP-HI groups had higher protein and fat intake and lower carbohydrate intake and GI than the MP-MI and MP-HI groups during WLM (HP-MI: protein∼22 E%, carbohydrate∼38 E%, fat∼35%, GI∼51; HP-HI: protein∼22 E%, carbohydrate∼37 E%, fat∼35%, GI∼51; MP-MI: protein∼19 E%, carbohydrate∼42 E%, fat∼34%, GI∼55; MP-HI: protein∼19 E%, carbohydrate∼43 E%, fat∼33%, GI∼56).…”