Subjects
Seventy-nine female subjects aged 18–60 years with a body mass index (BMI) of 26–31 kg/m2 were screened. Subjects with a history of cardiovascular, mental or other serious diseases, or a systolic blood pressure ≥160 mm Hg or a diastolic blood pressure ≥105 mm Hg, alcohol or substance abuse, history of soy bean or milk allergy and consumption of drugs affecting BW were not eligible to enter the study. For entering the randomized phase of the 12-week weight maintenance phase, subjects should reduce BW with at least 5% at the end of a six-week VLCD period.
The local ethics committee at the Faculty of Medicine at Uppsala University approved the study. Signed informed consent was obtained from all participants.
Study design
The study had a randomized, controlled, double-blind, parallel design and consisted of two phases; an initial weight reduction period of 6 weeks using a calorie-restricted diet, VLCD, followed by a random allocation to a test or control weight maintenance treatment period of 12 weeks. During the first 2 weeks of the weight reduction phase, the subjects consumed 5 units of Nutrilette Intensive daily (557 kcal Energy% C/F/P 37/21/42; Nutrilett Intensive chocolate, Axellus AB, Sweden), which gives 100% of RDI of minerals and vitamins. Nutrilette Intensive is a commercial product on the Swedish market and was purchased at a supermarket for this study. One unit of Nutrilette Intensive was added to 200 mL of cold water and immediately shaked for 10–15 s before consumption. The subjects were also strictly instructed to drink a minimum of 2.5 L of non-caloric beverage/day. No other food or drink items were allowed. During the remaining 4 weeks of the weight reduction phase, the subjects ingested ad lib a regular breakfast and 4 units of Nutrilette Intensive daily (111 kcal/unit, in total 444 kcal/day). All subjects received information and advice about a healthy breakfast meal. Subjects with a BW loss of at least 5% were randomized into the weight maintenance intervention phase of 12 weeks, during which the participants resumed to their habitual eating patterns except for the lunch, which was replaced by Nutrilette Intensive meal (111 kcal) mixed with test emulsion or control. The subject mixed one unit of Nutrilette Intensive with 200 mL of cold water as described previously and added the test or control emulsion to the mixture during stirring. The subjects were requested not to change their exercise habits during the study.
Products
The 12.5 g test vegetable-oil emulsion (Fabuless™, DSM Food specialties Delft, The Netherlands) contained 5.2 g fat and 7.3 g water (46 kcal/day), while the 13.8 g of cream, which was used as control, contained 5.2 g fat, 0.4 g protein, 0.3 g carbohydrate and 7.9 g water (49 kcal/day). The products were dispensed in a double-blind manner in ready to use portion packs for daily use. The subjects reported consumption in a diary, which together with the returned unused portion packs constituted the basis for calculation of the compliance.
Measurements
Body weight (BW), sagittal abdominal diameter SAG, waist and hip circumferences, skinfolds, heart rate and blood pressure measurements were performed every second week during the weight reduction phase and every fourth week during the weight maintenance period. The same equipments were used, and the same nurse performed the measurements during the study in order to increase the reproducibility of the measurements, and in addition, the weight loss phase was used as training of the subjects to become more comfortable with measurements (data not shown).
Anthropometric
BW was measured using a digital balance accurate (CL-300 BMI, Carl Liden, Gothenburg, Sweden) with subjects wearing indoor cloths without shoes, wallet and keys. Height was measured using a wall-mounted stadiometer at the screening visit. Body mass index (BMI) was calculated by dividing the BW (kg) by body height squared (m2). BFM and body muscle mass (BMM) were estimated by skinfold measurements at four different locations on the body: biceps, triceps, subscapular and suprailiac [21] and carried out with a Harpenden caliper (Baty Int, West Sussex, UK). The waist and hip circumferences were measured between the iliac crest and the lowest part of the lowest rib with the subjects in underwear in a standing position. The subject was asked to exhale before the waist circumference was performed. Sagittal abdominal diameter (SAG) was measured with the subject laying on the back, on a flat and hard surface and defined as the distance between the surface and the highest point of the abdomen.
Blood pressure and pulse rate
Blood pressure and pulse rate were measured oscillometrically (Omron M4-I, Omron Healthcare Europe B.V., Hoofddorp, The Netherlands) in the sitting position in the right arm after a resting period of 3–5 min. A total of three measurements with 2–5 min intervals were performed, and the average of these measurements was calculated.
Body temperature
Body temperature was measured rectal by Terumo Electronic Fever Thermometer C402. The same thermometer was used during the study.
Biochemical analyses
The subjects arrived at the study site after 12-h fasting. Plasma and serum were obtained from blood samples via venapuncture in the forearm for determination of hemoglobin (Hb), glycosylated hemoglobin (HbA1c), alanine aminotransferase (ALAT), triglycerides (TG), apolipoprotein A1 (ApoA1), apolipoprotein B (ApoB), gamma glutamyl transpeptidase (GGT), glucose (Glc), potassium (K), sodium (Na), creatinine (Crea) and thyroid-stimulating hormone (TSH). Urine dipstick analyses were carried out as well. The biochemical analyses were performed before the weight reduction phase, at baseline and after 12-week weight maintenance treatment and carried out at the Department of Clinical Chemistry, University Hospital, Uppsala.
Adverse events
All adverse events defined as any untoward occurrence in a subject in the study, whether considered related to the study treatment, were collected, documented and reported. An adverse event form was filled in for each separate adverse event.
Power calculation
Study group sizes were determined to detect a difference of 1.8 kg between test and control groups; with a power of 80% and a standard deviation (SD) of 2.0 and a type I error of 5%, a sample size of 21 subjects in each group was required, with a total of 42 subjects (Sample power, SPSS, Chicago, Illinois, USA). Drop out rate for the initial weight loss period as well as for the intervention period was set at 30% leading to a total number of 60 subjects to include in the weight reduction period (Fig. 1).
Statistics
Data are presented as mean and standard deviation (SD) or 95% confidence intervals (CI). Differences between test treatment and control treatment groups for baseline characteristics were analyzed with an unpaired t-test using SPSS version 15.0 (Chicago, Illinois, USA). The study of data evolution throughout the follow-up was performed with the analysis of variance for repeated measurements (ANOVA). For inferring a treatment effect from the difference between test group and control group on a quantitative outcome measured before and after treatment, analysis of covariance (ANCOVA) of the outcome with the baseline as covariate was performed (Univariate Mixed Effect Model Approach). Statistical analysis of variance as well as analysis of covariance was performed using SAS software (SAS Institute, Cary, NC, USA). p values <0.05 were considered statistically significant. Subjects were included in the statistical evaluation if compliance to treatment was at least 70%.