Validation of the Diet Satisfaction Questionnaire: a new measure of satisfaction with diets for weight management.

OBJECTIVE: The Diet Satisfaction Questionnaire was developed to fill the need for a validated measure to evaluate satisfaction with weight-management diets. This paper further develops the questionnaire, examining the factor structure of the original questionnaire, cross-validating a revised version in a second sample and relating diet satisfaction to weight loss during a 1-year trial. METHODS: The 45-item Diet Satisfaction Questionnaire (DSat-45) uses seven scales to assess characteristics that influence diet satisfaction: Healthy Lifestyle, Convenience, Cost, Family Dynamics, Preoccupation with Food, Negative Aspects, and Planning and Preparation. It was administered five times during a 1-year weight-loss trial (n = 186 women) and once as an online survey in a separate sample (n = 510 adults). Confirmatory factor analysis was used to assess and refine the DSat-45 structure, and reliability and validity data were examined in both samples for the revised questionnaire, the DSat-28. Associations were examined between both DSat questionnaires and weight loss in the trial. RESULTS: Internal consistency (reliability) was moderate for the DSat-45. Confirmatory factor analysis showed improved fit for a five-factor structure, resulting in the DSat-28 that retained four of the original scales and a shortened fifth scale. This revised questionnaire was reliable in both samples. Weight loss across the year-long trial was positively related to satisfaction with Healthy Lifestyle, Preoccupation with Food, and Planning and Preparation in both versions of the questionnaire. CONCLUSIONS: Measures of reliability and validity were improved in the more concise DSat-28 compared to the DSat-45. This shorter measure should be used in future work to evaluate satisfaction with weight-management diets.

Early predictors of weight loss in a 1-year behavioural weight-loss programme.

Objective: Identifying early predictors of weight loss is key for developing personalized treatment. However, few individual factors have been identified that predict weight loss during intervention, other than early weight loss itself. Methods: Women with overweight or obesity (n = 186, mean ± SD age 50.0 ± 10.6 years, body mass index 34.0 ± 4.2 kg m-2) participated in the Portion-Control Strategies Trial, a 1-year randomized controlled weight-loss trial with three intervention groups. Early changes in eating behaviours and psychological factors were evaluated by questionnaires at baseline and Month 1. The influence of these early changes on the trajectory of weight loss from baseline to Months 3 and 12 was assessed by random coefficients models. Results: Although there were no differences in weight loss between intervention groups at the end of the trial, certain individual factors were shown to predict both early weight loss at Month 3 and longer-term weight loss at Month 12. Across all participants, increases in dietary restraint and healthy lifestyle ratings in the first month predicted more rapid weight loss from baseline to Month 3 (P < 0.05) and also predicted more rapid weight loss and slower regain from baseline to Month 12 (both P < 0.01). Early attendance and changes in disinhibition were not associated with subsequent weight loss. Conclusions: Changes in psychological and behavioural measures, such as restraint, in the first month of weight loss intervention predicted longer-term weight loss in women. Early additional support or tailored treatment could promote long-term success by reinforcing these behaviours.

Does the incorporation of portion-control strategies in a behavioral program improve weight loss in a 1-year randomized controlled trial?

BACKGROUND/OBJECTIVES: Controlling food portion sizes can help reduce energy intake, but the effect of different portion-control methods on weight management is not known. In a 1-year randomized trial, we tested whether the efficacy of a behavioral weight-loss program was improved by incorporating either of the two portion-control strategies instead of standard advice about eating less. SUBJECTS/METHODS: The Portion-Control Strategies Trial included 186 women with obesity (81%) or overweight (19%). Participants were randomly assigned to one of three equally intensive behavioral programs, consisting of 19 individual sessions over 12 months. The Standard Advice Group was instructed to eat less food while making healthy choices, the Portion Selection Group was instructed to choose portions based on the energy density using tools such as food scales and the Pre-portioned Foods Group was instructed to structure meals around pre-portioned foods such as single-serving main dishes, for which some vouchers were provided. In an intention-to-treat analysis, a mixed-effects model compared weight loss trajectories across 23 measurements; at month 12, weight was measured for 151 participants (81%). RESULTS: The trajectories showed that the Pre-portioned Foods Group initially lost weight at a greater rate than the other two groups (P=0.021), but subsequently regained weight at a greater rate (P=0.0005). As a result, weight loss did not differ significantly across groups at month 6 (mean±s.e. 5.2±0.4 kg) or month 12 (4.5±0.5 kg). After 1 year, measured weight loss averaged 6% of baseline weight. The frequency of using portion-control strategies initially differed across groups, then declined over time and converged at months 6 and 12. CONCLUSIONS: Incorporating instruction on portion-control strategies within a 1-year behavioral program did not lead to a greater weight loss than standard advice. Using pre-portioned foods enhanced early weight loss, but this was not sustained over time. Long-term maintenance of behavioral strategies to manage portions remains a challenge.

Does nutrition information about the energy density of meals affect food intake in normal-weight women?

This study investigated whether the energy density of foods affected energy intake when subjects were informed about the energy density of their meals. Forty normal-weight women ate breakfast, lunch, and dinner in the laboratory on three separate days. The entrée at each meal was varied in energy density to be either 1.25, 1.50, or 1.75 kcal/g (5.23, 6.28, or 7.32 kJ/g), but was held similar in macronutrient composition and palatability. On each day, the entrées at all three meals had the same energy density. All entrées were consumed ad libitum. Subjects were assigned to one of two groups. Subjects in the information group received a nutrition label with each meal, which showed the energy density of the entrée. Subjects in the no-information group did not receive any nutrition information. The results revealed that subjects in both groups had the same pattern of food intake across the three levels of energy density. Energy density significantly affected energy intake; subjects in both groups combined consumed 22% less energy in the condition of low energy density than in the condition of high energy density (p < 0.0001). These findings show that energy density can have a significant influence on energy intake, even when individuals are informed about the energy density of their meals.

Effects of fruit and vegetable consumption on plasma antioxidant concentrations and blood pressure: a randomised controlled trial.

BACKGROUND: High dietary intakes of fruit and vegetables are associated with reduced risks of cancer and cardiovascular disease. Short-term intensive dietary interventions in selected populations increase fruit and vegetable intake, raise plasma antioxidant concentrations, and lower blood pressure, but long-term effects of interventions in the general population are not certain. We assessed the effect of an intervention to increase fruit and vegetable consumption on plasma concentrations of antioxidant vitamins, daily fruit and vegetable intake, and blood pressure. METHODS: We undertook a 6-month, randomised, controlled trial of a brief negotiation method to encourage an increase in consumption of fruit and vegetables to at least five daily portions. We included 690 healthy participants aged 25-64 years recruited from a primary-care health centre. FINDINGS: Plasma concentrations of alpha-carotene, beta-carotene, lutein, beta-cryptoxanthin, and ascorbic acid increased by more in the intervention group than in controls (significance of between-group differences ranged from p=0.032 to 0.0002). Groups did not differ for changes in lycopene, retinol, alpha-tocopherol, gamma-tocopherol, or total cholesterol concentrations. Self-reported fruit and vegetable intake increased by a mean 1.4 (SD 1.7) portions in the intervention group and by 0.1 (1.3) portion in the control group (between-group difference=1.4, 95% CI 1.2-1.6; p<0.0001). Systolic blood pressure fell more in the intervention group than in controls (difference=4.0 mm Hg, 2.0-6.0; p<0.0001), as did diastolic blood pressure (1.5 mm Hg, 0.2-2.7; p=0.02). INTERPRETATION: The effects of the intervention on fruit and vegetable consumption, plasma antioxidants, and blood pressure would be expected to reduce cardiovascular disease in the general population.

Randomised controlled trial of use by hypercholesterolaemic patients of a vegetable oil sterol-enriched fat spread.

Plant sterols may be a useful additive therapy in the treatment of hypercholesterolaemic patients. The purpose of this study was to determine the effect of a fat spread enriched with vegetable oil sterols on plasma lipid, lipoprotein and apolipoprotein concentrations. A randomised double blind placebo-controlled crossover trial with two consecutive periods of 8 weeks was conducted. 30 patients with heterozygous familial hypercholesterolaemia treated concurrently with an HMG-CoA reductase inhibitor (statin) and 32 patients with type IIa primary hypercholesterolaemia with a total cholesterol concentration >6.5 mmol/l not taking lipid-lowering drug therapy were recruited from a hospital lipid clinic. The active treatment was a fortified fat spread (25 g/day) providing 2.5 g of plant sterols. The control spread was indistinguishable in taste and appearance. Comparison at the end of the two 8-week trial periods showed a statistically significant reduction in total and LDL-cholesterol with use of the fortified spread but the results were confounded by a carry-over effect, which was partly explained by changes in the background diet. Because a carry-over effect was present, further analyses were restricted to the parallel arms of the first treatment period and were conducted on an intention to treat basis. After 4 weeks, LDL-cholesterol had decreased by 0.04 mmol/l ([0.8%] 95% confidence interval -0.44-0.37 NS) in the placebo group and decreased by -0.76 mmol/l ([15.0%] 95% CI -1.03--0.48, P<0.0001) in the active treatment group. After 8 weeks, the corresponding results were 0.0 mmol/l ([0.0%] 95% CI -0.26-0.24 NS) and -0.51 mmol/l ([10.0%] 95% CI -0.73--0.29 P<0.0001). There were no significant changes in apolipoprotein AI or B concentrations in the placebo group, but there was a small but statistically significant increase in apolipoprotein AI and a decrease in apolipoprotein B in the active treatment group. HDL cholesterol and triglyceride concentrations were unchanged. There was no difference in response between patients with statin-treated familial hypercholesterolaemia and patients with type IIa hyperlipoproteinaemia. We conclude that a fortified fat spread enriched with vegetable oil sterols reduces LDL-cholesterol by 10-15% with no difference in response between hypercholesterolaemic patients prescribed statins and those not taking lipid-lowering drug therapy.