The Eat Smart Study: a randomised controlled trial of a reduced carbohydrate versus a low fat diet for weight loss in obese adolescents

Study Protocol of a Multicenter Randomized Controlled Trial to Tackle Obesity through a Mediterranean Diet vs. a Traditional Low-Fat Diet in Adolescents: The MED4Youth Study

Youth obesity is a strong predictor of adult obesity, which has well-known negative health consequences. Thus, addressing adult obesity requires tackling youth obesity. MED4Youth's main objective is to strengthen the link between the Mediterranean Diet (MD) and the health benefits against youth obesity and associated cardiovascular disease (CVD) risk factors, identifying positive effects exerted by an MD including sourdough bread and healthy products from the Mediterranean basis (chickpeas/hummus, nuts, and pomegranate juice). For this purpose, a multicenter randomized controlled trial in which an MD-based intervention will be compared to a traditional low-fat diet intervention will be carried out with 240 overweight and obese adolescents (13-17 years) from Spain, Portugal, and Italy. Both interventions will be combined with an educational web-application addressed to engage the adolescents through a learning-through-playing approach, using both educational materials and games. To assess the interventions, adherence to the MD, dietary records, physical activity, food frequency, sociodemographic, and quality of life questionnaires as well as classical anthropometric and biochemical parameters will be evaluated. Furthermore, an omics approach will be performed to elucidate whether the interventions can shape the gut microbiota and gut-derived metabolites to gain knowledge on the mechanisms through which the MD can exert its beneficial effects.

A Randomized Controlled Trial of Two Different Macronutrient Profiles on Weight, Body Composition and Metabolic Parameters in Obese Adolescents Seeking Weight Loss

Objective

Adolescent obesity is difficult to treat and the optimal dietary pattern, particularly in relation to macronutrient composition, remains controversial. This study tested the effect of two structured diets with differing macronutrient composition versus control, on weight, body composition and metabolic parameters in obese adolescents.

Design

A randomized controlled trial conducted in a children’s hospital.

Methods

Eighty seven obese youth (means: age 13.6 years, BMI z-score 2.2, waist: height ratio 0.65, 69% female) completed a psychological preparedness program and were then randomized to a short term ‘structured modified carbohydrate’ (SMC, 35% carbohydrate; 30% protein; 35% fat, n = 37) or a ‘structured low fat’ (SLF, 55% carbohydrate; 20% protein; 25% fat, n = 36) or a wait listed control group (n = 14). Anthropometric, body composition and biochemical parameters were measured at randomization and after 12 weeks, and analyzed under the intention to treat principle using analysis of variance models.

Results

After 12 weeks, data was collected from 79 (91%) participants. BMI z-scores were significantly lower in both intervention groups compared to control after adjusting for baseline values, SLF vs. control, mean difference = -0.13 (95%CI = -0.18, -0.07), P<0.001; SMC vs. control, -0.14 (-0.19, -0.09), P<0.001, but there was no difference between the two intervention diet groups: SLF vs. SMC, 0.00 (-0.05, 0.04), P = 0.83.

Conclusions

Both dietary patterns resulted in similar changes in weight, body composition and metabolic improvements compared to control. The use of a structured eating system which allows flexibility but limited choices can assist in weight change and the rigid application of a low fat eating pattern is not exclusive in its efficacy.

Trial Registration

International Clinical Trials Registry ISRCTN49438757

Fasting gut hormone levels change with modest weight loss in obese adolescents

BACKGROUND

Gut hormones change with weight loss in adults but are not well studied in obese youth.

OBJECTIVE

The primary aim was to evaluate how gut hormones and subjective appetite measure change with dietary weight loss in obese adolescents.

METHODS

Participants were a subset of those taking part in the 'Eat Smart Study'. They were aged 10-17 years with body mass index (BMI) > 90th centile and were randomized to one of three groups: wait-listed control, structured reduced carbohydrate or structured low-fat dietary intervention for 12 weeks. Outcomes were fasting glucose, insulin, leptin, adiponectin, total amylin, acylated ghrelin, active glucagon-like peptide-1, glucose-dependent insulinotropic polypeptide (GIP), pancreatic polypeptide (PP) and total peptide tyrosine-tyrosine. Pre- and postprandial subjective sensations of appetite were assessed using visual analogue scales.

RESULTS

Of 87 'Eat Smart' participants, 74 participated in this sub-study. The mean (standard deviation) BMI z-score was 2.1 (0.4) in the intervention groups at week 12 compared with 2.2 (0.4) in the control group. Fasting insulin (P = 0.05) and leptin (P = 0.03) levels decreased, while adiponectin levels increased (P = 0.05) in the intervention groups compared with control. The intervention groups were not significantly different from each other. A decrease in BMI z-score at week 12 was associated with decreased fasting insulin (P < 0.001), homeostatic model of assessment-insulin resistance (P < 0.001), leptin (P < 0.001), total amylin (P = 0.03), GIP (P = 0.01), PP (P = 0.02) and increased adiponectin (P < 0.001). There was no significant difference in appetite sensations.

CONCLUSIONS

Modest weight loss in obese adolescents leads to changes in some adipokines and gut hormones that may favour weight regain.

Predicting success: factors associated with weight change in obese youth undertaking a weight management program

OBJECTIVE

To explore which baseline physiological and psychosocial variables predict change in body mass index (BMI) z-score in obese youth after 12 weeks of a dietary weight management study.

METHODS

Participants were obese young people participating in a dietary intervention trial in Brisbane Australia. The outcome variable was change in BMI z-score. Potential predictors considered included demographic, physiological and psychosocial parameters of the young person, and demographic characteristics of their parents. A multivariable regression model was constructed to examine the effect of potential predictive variables.

RESULTS

Participants (n = 88) were predominantly female (69.3%), and had a mean(standard deviation) age of 13.1(1.9) years and BMI z-score of 2.2(0.4) on presentation. Lower BMI z-score (p < 0.001) and insulin resistance (p = 0.04) at baseline, referral from a paediatrician (p = 0.02) and being more socially advantaged (p = 0.046) were significantly associated with weight loss. Macronutrient distribution of diet and physical activity level did not contribute.

CONCLUSIONS

Early intervention in obesity treatment in young people improves likelihood of success. Other factors such as degree of insulin resistance, social advantage and referral source also appear to play a role. Assessing presenting characteristics and factors associated with treatment outcome may allow practicing clinicians to individualise a weight management program or determine the 'best-fit' treatment for an obese adolescent.

Active buildings: modelling physical activity and movement in office buildings. An observational study protocol

INTRODUCTION

Health benefits of regular participation in physical activity are well documented but population levels are low. Office layout, and in particular the number and location of office building destinations (eg, print and meeting rooms), may influence both walking time and characteristics of sitting time. No research to date has focused on the role that the layout of the indoor office environment plays in facilitating or inhibiting step counts and characteristics of sitting time. The primary aim of this study was to investigate associations between office layout and physical activity, as well as sitting time using objective measures.

METHODS AND ANALYSIS

Active buildings is a unique collaboration between public health, built environment and computer science researchers. The study involves objective monitoring complemented by a larger questionnaire arm. UK office buildings will be selected based on a variety of features, including office floor area and number of occupants. Questionnaires will include items on standard demographics, well-being, physical activity behaviour and putative socioecological correlates of workplace physical activity. Based on survey responses, approximately 30 participants will be recruited from each building into the objective monitoring arm. Participants will wear accelerometers (to monitor physical activity and sitting inside and outside the office) and a novel tracking device will be placed in the office (to record participant location) for five consecutive days. Data will be analysed using regression analyses, as well as novel agent-based modelling techniques.

ETHICS AND DISSEMINATION

The results of this study will be disseminated through peer-reviewed publications and scientific presentations. Ethical approval was obtained through the University College London Research Ethics Committee (Reference number 4400/001).

Use of the waist-height ratio to predict metabolic syndrome in obese children and adolescents

AIM

To demonstrate that the waist-height ratio (WHtR) is a simple and effective screening tool that could be used to identify obese children with the metabolic syndrome.

METHODS

Data from 109 obese boys and girls, aged 10.00-16.50 years, who were recruited as part of the Eat Smart study were analysed. Systolic (SBP) and diastolic (DBP) blood pressure, blood lipids (total cholesterol, triglycerides (TG), high- and low-density lipoproteins), insulin, glucose, height, weight and waist circumference (WC) were collected. These measurements were used to calculate WHtR, body mass index (BMI), Z-scores for BMI, WC, weight and homeostatic model assessment for insulin resistance (HOMA-IR). Correlations between anthropometric measures and blood pressure, lipids, insulin, glucose and HOMA-IR were assessed. Binary logistic regression was used to test which anthropometric measure was a significant predictor of the metabolic syndrome.

RESULTS

Among boys, WHtR was negatively correlated with glucose (P < 0.05); WHtR and BMI Z-score were positively correlated with insulin, HOMA-IR and TG (P < 0.05) and WC Z-score was significantly correlated with age. Among girls, WHtR, BMI Z-score and WC Z-score were positively correlated with insulin and HOMA-IR and negatively correlated with high-density lipoprotein-cholesterol (P < 0.05), whereas BMI Z-score was significantly correlated with SBP and DBP Z-scores. Twenty per cent of subjects were classified as having the metabolic syndrome, with WHtR, BMI Z-score and HOMA-IR being significant predictors.

CONCLUSION

The WHtR is a significant predictor of the metabolic syndrome in obese youth. The WHtR is the simplest index to calculate and interpret, making it an ideal non-invasive screening tool to use in clinical practice.