Weight loss maintenance in overweight subjects on ad libitum diets with high or low protein content and glycemic index: the DIOGENES trial 12-month results.

BACKGROUND: A high dietary protein (P) content and low glycemic index (LGI) have been suggested to be beneficial for weight management, but long-term studies are scarce. OBJECTIVE: The DIOGENES randomized clinical trial investigated the effect of P and GI on weight loss maintenance in overweight or obese adults in eight centers across Europe. This study reports the 1-year results in two of the centers that extended the intervention to 1 year. METHOD: After an 8-week low-calorie diet (LCD), 256 adults (body mass index >27 kg m(-)(2)) were randomized to five ad libitum diets for 12 months: high P/LGI (HP/LGI), HP/high GI (HP/HGI), low P/LGI (LP/LGI), LP/HGI and a control diet. During the first 6 months, foods were provided for free through a shop system and during the whole 12-month period, subjects received guidance by a dietician. Primary outcome variable was the change in body weight over the 12-month intervention period. RESULTS: During the LCD period, subjects lost 11.2 (10.8, 12.0) kg (mean (95% confidence interval (CI))). Average weight regain over the 12-month intervention period was 3.9 (95% CI 3.0-4.8) kg. Subjects on the HP diets regained less weight than subjects on the LP diets. The difference in weight regain after 1 year was 2.0 (0.4, 3.6) kg (P=0.017) (completers analysis, N=139) or 2.8 (1.4, 4.1) kg (P<0.001) (intention-to-treat analysis, N=256). No consistent effect of GI on weight regain was found. There were no clinically relevant differences in changes in cardiometabolic risk factors among diet groups. CONCLUSION: A higher protein content of an ad libitum diet improves weight loss maintenance in overweight and obese adults over 12 months.

Experience and acceptability of diets of varying protein content and glycemic index in an obese cohort: results from the Diogenes trial.

BACKGROUND/OBJECTIVES: To investigate acceptability and tolerability of diets of different protein and glycemic index (GI) content aimed at weight maintenance following a phase of rapid weight loss, as part of a large pan-European dietary intervention trial. SUBJECTS/METHODS: The Diogenes study (www.diogenes-eu.org) consisted of an initial 8-week rapid weight-loss phase (800-1000 kcal/day), followed by a 6-month weight maintenance intervention with five different diets varying in protein and GI content. Measurement of a range of outcomes relating to experience of the Diogenes diets in terms of acceptability, experience and mood were recorded via end of day questionnaires throughout the study. RESULTS: Weight change during the initial weight loss phase weakly, but positively correlated with acceptability of the programme (r range=-0.08 to 0.2, P 0.05, n=685 on four of five dimensions). Success at weight maintenance positively correlated with acceptance of the programme (r range=-0.21 to -0.34, P<0.001, n=540 for all five dimensions). The diets with higher protein content were more acceptable than the low protein (LP) diets, however, no differences between the high vs low GI diets were found concerning acceptability and tolerability. CONCLUSIONS: Results suggest that moderately high protein diets, compared with LP diets, are more acceptable diets for weight control in overweight individuals.

Fatty acid composition of adipose tissue triglycerides after weight loss and weight maintenance: the DIOGENES study.

Fatty acid composition of adipose tissue changes with weight loss. Palmitoleic acid as a possible marker of endogenous lipogenesis or its functions as a lipokine are under debate. Objective was to assess the predictive role of adipose triglycerides fatty acids in weight maintenance in participants of the DIOGENES dietary intervention study. After an 8-week low calorie diet (LCD) subjects with > 8 % weight loss were randomized to 5 ad libitum weight maintenance diets for 6 months: low protein (P)/low glycemic index (GI) (LP/LGI), low P/high GI (LP/HGI), high P/low GI (HP/LGI), high P/high GI (HP/HGI), and a control diet. Fatty acid composition in adipose tissue triglycerides was determined by gas chromatography in 195 subjects before the LCD (baseline), after LCD and weight maintenance. Weight change after the maintenance phase was positively correlated with baseline adipose palmitoleic (16:1n-7), myristoleic (14:1n-5) and trans-palmitoleic acid (16:1n-7t). Negative correlation was found with baseline oleic acid (18:1n-9). Lower baseline monounsaturated fatty acids (14:1n-5, 16:1n-7 and trans 16:1n-7) in adipose tissue triglycerides predict better weight maintenance. Lower oleic acid predicts lower weight decrease. These findings suggest a specific role of monounsaturated fatty acids in weight management and as weight change predictors.

Circulating ACE is a predictor of weight loss maintenance not only in overweight and obese women, but also in men.

BACKGROUND: Circulating angiotensin-converting enzyme (ACE) was identified as a predictor of weight loss maintenance in overweight/obese women of the Diogenes project. OBJECTIVE: To investigate whether ACE acted also as a predictor in men of the Diogenes study and to compare it with that in women. DESIGN: Subjects, who lost ≥ 8% of body weight induced by low-caloric diet in an 8-week weight loss period, were assigned to weight loss maintenance with dietary intervention for 6 months. SUBJECTS: 125 overweight/obese healthy men from eight European countries who completed whole intervention. MEASUREMENTS: Concentrations and activity of serum ACE at baseline and after the 8-week weight loss, in addition to anthropometric and physiological parameters. RESULTS: Serum ACE concentration decreased by 11.3 ± 10.6% during the weight loss period in men. A greater reduction is associated with less body weight regain during the maintenance period (r=0.227, P=0.012). ACE change was able to predict a weight regain ≤ 20% after 6 months, with an odds ratio of 1.59 (95% confidence interval (CI): 1.09-2.33, P=0.016) for every 10% reduction, which was independent of body mass index and weight loss. The prediction power was weaker in men than in women, but without a significant sex difference (P=0.137). In pooled subjects (N=218), the odds ratio was 1.96 (95% CI: 1.46-2.64, P<0.001). CONCLUSIONS: A greater reduction of ACE during weight loss is favorable for weight maintenance in both men and women. This can offer useful information for personalized advice to improve weight loss maintenance. It also confirms the role of ACE in the metabolic pathways of weight regulation.

Predictors of weight loss maintenance and attrition during a 6-month dietary intervention period: results from the DiOGenes study.

There is a need to develop tools to predict individual weight loss maintenance and attrition prognosis. We aimed to identify predictors of weight loss maintenance outcome and attrition in subjects from eight European countries in the DiOGenes project. A total of 932 overweight/obese subjects (body mass index: 27-42 kg m(-2) ) were enrolled in an 8-week low-calorie diet (LCD). The 776 subjects (83%) who achieved at least 8% reduction in their initial body weight were randomized into five dietary arms varying in protein content and glycemic index for a 6-month weight maintenance period. Baseline characteristics, weight loss at weeks 1, 3 and 8 of LCD were assessed as predictors of weight loss maintenance and attrition using multivariate regression and correlation models. The multivariate model showed that the 6-month weight loss maintenance was predicted by: 7.889 - 0.343 × weight loss at week 3 + 1.505 × weight loss at week 8 + 2.422 × gender (0 = male and 1 = female gender) (R(2) = 51%, P = 0.0001). A greater weight loss at week 8 was associated with a lower attrition during the subsequent 6-month dietary intervention period (OR = 0.92, 95% CI: 0.88-0.97, P = 0.001). Furthermore, the men showed an increased likelihood for attrition during the dietary intervention period (OR = 1.54, 95% CI: 1.07-2.20, P = 0.02). A greater weight loss during 8 weeks of LCD and female gender predict better 6-month weight maintenance of weight loss, whereas the baseline characteristics did not predict outcome. Attrition could be strongly predicted by gender and weight loss during LCD.

Developing a methodology for assigning glycaemic index values to foods consumed across Europe.

There is growing evidence that the glycaemic index (GI) of the diet is important with respect to body weight and metabolic disease risk. However, research is limited by the paucity of GI values for commonly consumed carbohydrate-rich foods in European countries. A new methodology has been developed for consistent assignment of GI values to foods across five European databases used in the Diogenes intervention study. GI values were assigned according to five decreasing levels of confidence (1) Measured values for specific foods; (2) Published values from published sources; (3) Equivalent values where published values for similar foods existed; (4) Estimated values assigned as one of three values representing low/medium/high GI ranges and (5) Nominal values assigned as 70, where no other value could be assigned with sufficient confidence. GI values were assigned to 5105 foods. In food records collected at baseline, the contribution to carbohydrate intake of foods assigned levels 1-2 ranged from 16% to 43% depending on country, and this increased to 53-81% including level 3 foods. The degree of confidence to assigned GI values differed across Europe. This standardized approach of assigning GI values will be made available to other researchers to facilitate further investigation into the effects of dietary GI on health.

Initial weight loss on an 800-kcal diet as a predictor of weight loss success after 8 weeks: the Diogenes study.

OBJECTIVE: The purpose of this study was to investigate whether pre-treatment subject characteristics and weight change during the first weeks of a low-calorie diet (LCD) can predict weight loss outcomes at the end of a controlled 8-week weight loss period in overweight and obese adults. SUBJECTS: A total of 932 overweight and obese subjects of both genders were included at eight European centers, and underwent an 8-week LCD period. RESULTS: The weight loss at week 8 was positively correlated with initial body weight (Spearman's rho=0.62), height (rho=0.43), body mass index (rho=0.43), waist (rho=0.48) and hip circumference (rho=0.33), sagittal diameter (rho=0.45), fat mass (rho=0.35) and fat-free mass (rho=0.52), and gender (rho=-0.36) (all P<0.01). In the multivariate regression model, adjusted for center, only initial body weight, early weight loss (week 1) and weight loss at week 3 were significant predictors of weight loss outcome at week 8: weight loss (kg) at week 8=0.09+0.046 x baseline body weight (kg)-0.311 x weight loss (kg) at week 1+1.284 x weight loss (kg) at week 3 (R(2)=68%, P<0.0001). A weight loss of > or =2.6 kg at week 1 during the LCD period was identified as the optimal cut-off predictor for at least 10 kg weight loss at week 8. CONCLUSIONS: This study suggests that initial body weight, early weight loss (week 1) and weight loss at week 3 are predictors of final weight loss during an 8-week LCD, and may be used as early biomarkers of subsequent responses to an LCD diet.

The Diet, Obesity and Genes (Diogenes) Dietary Study in eight European countries - a comprehensive design for long-term intervention.

Diogenes is a Pan-European, randomized, controlled dietary intervention study investigating the effects of dietary protein and glycaemic index on weight (re)gain, metabolic and cardiovascular risk factors in obese and overweight families in eight European centres. The article is methodological in character, and the presentation of 'results' will be limited to baseline characteristics of the study populations included. A total of 891 families with at least one overweight/obese parent underwent screening. The parents started an initial 8-week low-calorie diet and families with minimum one parent attaining a weight loss of > or = 8%, were randomized to one of five energy ad libitum, low-fat (25-30 E%) diets for 6 or 12 months: low protein/low glycaemic index, low protein/high glycaemic index, high protein/low glycaemic index, high protein/high glycaemic index or control (national dietary guidelines). At two centres the families were provided dietary instruction plus free foods for 6 months followed by 6-month dietary instruction only. At the remaining six centres the families received dietary instruction only for 6 months. The median weight loss during the low-calorie diet was 10.3 kg (inter-quartile range: 8.7-12.8 kg, n = 775). A total of 773 adults and 784 children were randomized to the 6-month weight (re)gain prevention phase. Despite major cultural and dietary regional differences in Europe, interventions addressing effects of dietary factors are feasible with a reasonable attrition.

Dietary strategy to manipulate ad libitum macronutrient intake, and glycaemic index, across eight European countries in the Diogenes Study.

The aim of this study was to describe the development and implementation of a multifaceted, low-fat, weight-loss strategy for a Pan-European randomized controlled dietary intervention study, Diogenes. There were 891 families with at least one overweight/obese parent who underwent screening. Eligible, overweight/obese adults followed an 8-week weight-loss phase with a fixed low-energy diet (800 kcal). On attaining weight loss of > or = 8%, families were randomized to a 6- or 12-month low-fat (25-30%E) diet either based on national dietary guidelines or one of four interventions: low protein (LP)/low glycaemic index (LGI), LP/high GI (HGI), high protein (HP)/LGI and HP/HGI. The impact of each diet in preventing weight (re)gain was tested. A points-based system was used to manipulate dietary protein and carbohydrate. Manipulating carbohydrate composition involved substituting foods with a relatively high or low GI. A questionnaire was designed and completed by study investigators, providing feedback on the dietary intervention methods used to inform future interventions. The points system allowed macronutrient manipulations without compromising dietary flexibility or enforcing energy restrictions. Reported centre/participant differences in the ease of implementing the intervention may reflect dietary diversity and personal preferences for specific weight-management strategies. The points system provides a useful starting point for designing improved experimental paradigms for the manipulation of dietary intake in future trials.

The effect of high-fat diet on plasma ghrelin and leptin levels in rats.

Ghrelin and leptin regulate appetite and energy homeostasis in humans and rodents. The effects of different nutritional factors on ghrelin and leptin secretion are not well documented in rats. Therefore, the aim of our study was to investigate the effect of a high-fat diet on plasma ghrelin and leptin levels and on adiposity. Twenty male Wistar rats, body weight 220-260 g, were used in the study. Rats were randomized either on a standard chow diet (n=10) or on a high-fat diet (a mixture of nuts) for ad libitum 11-week period. Body weight was measured once per week. At the end of the nutritional period, rats were sacrificed. Blood was collected for determination of lipids and glucose, as well as plasma ghrelin and leptin levels by ELISA method. The weight of different organs was determined. Rats fed on a high-fat diet showed significant increase in total body weight compared to control group. The long-term intake of high-fat diet caused hyperleptinemia and hypoghrelinemia. There was a significant positive correlation between plasma leptin levels and epididymal fat mass, liver and heart. In contrast, ghrelin levels showed inverse correlation with epididymal fat mass and liver weight. In conclusion, long-term intake of high-fat diet induced changes in plasma ghrelin and leptin in male rats, as well as in epididymal fat mass, liver and heart weights.

The effect of high-fat diet on plasma ghrelin and leptin levels in rats

Ghrelin and leptin regulate appetite and energy homeostasis in humans androdents. The effects of different nutritional factors on ghrelin and leptin secretion arenot well documented in rats. Therefore, the aim of our study was to investigate theeffect of a high-fat diet on plasma ghrelin and leptin levels and on adiposity. Twentymale Wistar rats, body weight 220-260 g, were used in the study. Rats were randomizedeither on a standard chow diet (n=10) or on a high-fat diet (a mixture of nuts)for ad libitum 11-week period. Body weight was measured once per week. At the endof the nutritional period, rats were sacrificed. Blood was collected for determinationof lipids and glucose, as well as plasma ghrelin and leptin levels by ELISA method.The weight of different organs was determined. Rats fed on a high-fat diet showedsignificant increase in total body weight compared to control group. The long-termintake of high-fat diet caused hyperleptinemia and hypoghrelinemia. There was a significantpositive correlation between plasma leptin levels and epididymal fat mass,liver and heart. In contrast, ghrelin levels showed inverse correlation with epididymalfat mass and liver weight. In conclusion, long-term intake of high-fat dietinduced changes in plasma ghrelin and leptin in male rats, as well as in epididymal fatmass, liver and heart weights(AU)