Anna Karin Lindroos

The Effect of Protein and Glycemic Index on Children's Body Composition: The DiOGenes Randomized Study

OBJECTIVE: To investigate the effect of protein and glycemic index (GI) on body composition among European children in the randomized, 6-month dietary intervention DiOGenes (diet, obesity, and genes) family-based study. PATIENTS AND METHODS: In the study, 827 children (381 boys and 446 girls), aged 5 to 18 years, completed baseline examinations. Families with parents who lost ≥8% of their weight during an 8-week run-in low-calorie diet period were randomly assigned to 1 of 5 ad libitum diets: low protein (LP)/low glycemic index (LGI); LP/high GI (HGI); high protein (HP)/LGI; HP/HGI; and control diet. The target difference was 15 GI U between the LGI/HGI groups and 13 protein percentage points between the LP/HP groups. There were 658 children examined after 4 weeks. Advice on food-choice modification was provided at 6 visits during this period. No advice on weight loss was provided because the focus of the study was the ability of the diets to affect outcomes through appetite regulation. Anthropometric measurements and body composition were assessed at baseline, week 4, and week 26. RESULTS: In the study, 465 children (58.1%) completed all assessments. The achieved differences between the GI and protein groups were 2.3 GI U and 4.9 protein percentage points, respectively. The LP/HGI group increased body fat percentage significantly more than the other groups (P = .040; partial η2 = 0.039), and the percentage of overweight/obese children in the HP/LGI group decreased significantly during the intervention (P = .031). CONCLUSIONS: Neither GI nor protein had an isolated effect on body composition. However, the LP/HGI combination increased body fat, whereas the HP/LGI combination was protective against obesity in this sample of children.

A proposed method of bias adjustment for meta-analyses of published observational studies

Objective Interpretation of meta-analyses of published observational studies is problematic because of numerous sources of bias. We develop bias assessment, elicitation and adjustment methods, and apply them to a systematic review of longitudinal observational studies of the relationship between objectively measured physical activity and subsequent change in adiposity in children. Methods We separated internal biases that reflect study quality from external biases that reflect generalizability to a target setting. Since published results were presented in different formats, these were all converted to correlation coefficients. Biases were considered as additive or proportional on the correlation scale. Opinions about the extent of each bias in each study, together with its uncertainty, were elicited in a formal process from quantitatively trained assessors for the internal biases and subject-matter specialists for the external biases. Bias-adjusted results for each study were combined across assessors using median pooling, and results combined across studies by random-effects meta-analysis. Results Before adjusting for bias, the pooled correlation is difficult to interpret because the studies varied substantially in quality and design, and there was considerable heterogeneity. After adjusting for both the internal and external biases, the pooled correlation provides a meaningful quantitative summary of all available evidence, and the confidence interval incorporates the elicited uncertainties about the extent of the biases. In the adjusted meta-analysis, there was no apparent heterogeneity. Conclusion This approach provides a viable method of bias adjustment for meta-analyses of observational studies, allowing the quantitative synthesis of evidence from otherwise incompatible studies. From the meta-analysis of longitudinal observational studies, we conclude that there is no evidence that physical activity is associated with gain in body fat.

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 ≥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.

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.

Prevalence of night eating in obese and nonobese twins

The aim of this study was to assess the prevalence of night eating (NE) and associated symptoms in a population‐based sample of Swedish twins. A total of 21,741 individuals aged 20–47 years completed a questionnaire in 2005/2006. NE was defined as ≥25% of daily food intake after the evening meal and/or awakening at least once per week with eating episodes. The prevalence of NE was 4.6% in men and 3.4% in women. Among obese men and women, the prevalence was 8.4 and 7.5%, respectively. Men and women with NE had 3.4 and 3.6 times higher risk of binge eating compared to individuals without NE. The risk of sleep‐related problems was 1.6–3.4 times higher in men and 2.5–3.3 times higher in women with NE compared to those without NE. This epidemiological study has estimated the prevalence of NE in a twin population. It revealed that NE is 2.5 and 2.8 times more common in obese men and women compared to normal weight men and women. Furthermore that NE is associated with binge eating and sleep‐related problems.

Eating habits in relation to body fatness and gender in adolescents – results from the ‘SWEDES’ study

Objective:To investigate if eating habits among adolescents are related to body fatness and gender.Design:Cross-sectional study.Setting:Obesity Unit, Huddinge University Hospital, Sweden, 2001–2002.Subjects:Two hundred and seventy-five girls and 199 boys, aged 16–17 years.Method:Questionnaires were used for dietary intake and meal frequency, BodPod for measuring body fatness (BF%). In all, 169 girls and 128 boys were classified as adequate reporters (AR) of energy intake, and were used in the dietary analyses. The whole sample was used in the meal frequency analyses.Results:The correlation between reported energy intake and weight in the AR group was 0.23 (P<0.01) for girls and 0.36 for boys (P<0.001). The correlations were inverse or not significant in the whole sample. The following variables correlated significantly with a high BF% (r s=±0.2): a low intake of milk in both girls and boys, a high intake of fibre and alcohol and a low intake of sugar in girls and a low intake of breakfast cereals in boys. Those with regular breakfast habits had healthier food choices than others, but this was not related to BF%. Boys had more meals per day (4.9 vs 4.6, P=0.02), especially early in the morning and late at night, whereas girls reported a higher relative intake of light meals and fruit and a lower intake of milk than boys.Conclusions:A few associations between eating habits and body fatness were found, but without any obvious patterns. The true differences in eating habits between lean and overweight adolescents are probably very small.

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.

Correlates of soft drink and fruit juice consumption among Swedish adolescents.

The aim of the study was to investigate how soft drink and fruit juice consumption in teenagers is associated with life-style, other food choices, eating behaviour and maternal characteristics. A cross-sectional study of 16-year-old girls (n 275) and boys (n 199) and their mothers was undertaken. Questionnaires were used to assess habitual dietary intake, eating behaviour, physical activity, smoking and educational level. Weight and height were measured. It was found that eating breakfast less than five times per week was independently associated with a high soft drink consumption in both girls and boys. A low intake of cooked meals and milk and a high intake of salty snacks were associated with soft drinks in boys only, and a low intake of fruits in girls only. A high maternal juice intake, low milk and high fruit consumption were independent correlates of fruit juice intake in both girls and boys. In girls, being a smoker, having a smoking mother, a high soft drink intake, scoring low on emotional eating and high on cognitive restraint were also associated with fruit juice intake. A low intake of soft drinks and cooked meals was associated with fruit juice intake in boys only. Neither soft drinks nor fruit juice was associated with BMI. In conclusion, a high intake of both fruit juice and soft drinks were associated with a lower intake of foods such as milk and cooked meals. It might be possible to influence fruit juice intake among teenagers by aiming at their mothers, whereas the adolescents themselves should be targeted when the aim is to reduce soft drink consumption.

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.

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) (R2 = 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.