Disrupting future discounting: a commentary on an underutilised psychological approach for improving adherence to diet and physical activity interventions

Non-communicable diseases (NCD) such as CVD and type 2 diabetes mellitus are major contributors to the burden of disease. NCD are largely driven by modifiable lifestyle factors including poor diet and insufficient physical activity, and consequently, prevention is a public health priority. Although diet and physical activity levels can be improved via lifestyle interventions, long-term adherence to such interventions remains low, which limits their effectiveness. Thus, it is critical to identify the underlying mechanisms that challenge uptake and adherence to such interventions. The current commentary discusses an important, but underexplored, psychological driver of poor adherence to lifestyle interventions, namely, future discounting, which describes the tendency to prefer smaller, short-term rewards over larger, long-term rewards. For example, in the nutrition domain, future discounting refers to valuing the immediate reward of excessive intake of energy-dense, nutrient-poor, discretionary foods high in salt, sugar, and saturated fat, and insufficient intake of low-energy, nutrient-dense, whole foods such as vegetables. Prominent theoretical models propose that excessive future discounting is a major contributor to the development of unhealthy lifestyle behaviours. Furthermore, a vast body of evidence suggests that future discounting plays a key role in risk of NCD. Thus, the evidence to date supports the idea that future discounting is an important multi-behaviour target for supporting lifestyle behaviour change; however, this approach has been largely neglected in preventive health efforts. Furthermore, this commentary discusses promising techniques (e.g. Episodic Future Thinking) for disrupting future discounting to promote improved adherence to lifestyle interventions aimed at reducing NCD risk.

Predictors of Lifestyle Intervention Attrition or Weight Loss Success in Women with Polycystic Ovary Syndrome Who Are Overweight or Obese

Background/objectives: Polycystic ovary syndrome (PCOS) is a common condition in reproductive-aged women. Weight management is a first-line treatment for PCOS according to international evidence-based guidelines. However, the factors associated with attrition or success in weight loss interventions are not known for women with PCOS. The objective of this study was to identify characteristics associated with attrition and weight loss success in women with PCOS and overweight or obesity undergoing weight loss interventions. Methods: Four randomised controlled clinical weight loss trials comprising energy restricted diets and/or exercise interventions of 2⁻8 months duration. The interventions were conducted over 2001⁻2007 in outpatient clinical research centres with n = 221 premenopausal women with PCOS and overweight/obesity recruited through community advertisement. The main outcome measures were attrition and ≥5% weight loss at 2 months and study completion. Results: Weight loss was 5.7 ± 2.9 kg at 2 months and 7.4 ± 5.3 kg after study completion (p < 0.001). Attrition was 47.1% and ≥5% weight loss occurred in 62.5% and 62.7% of women at 2 months and study completion respectively. Baseline depressive symptoms (OR 1.07 95% CI 0.88, 0.96, p = 0.032) and lower appointment attendance by 2 months (OR 0.92 95% CI 0.88, 0.96, p < 0.001) were independently associated with attrition. Lower appointment attendance over the whole study was independently associated with not achieving ≥5% weight loss at study completion (OR 0.95 95% CI 0.92, 0.99, p = 0.020). Conclusions: Despite high attrition, successful weight loss was achieved by 63% of women with PCOS in a clinical research setting. Higher baseline depressive symptoms were associated with greater attrition and higher appointment attendance was associated with lower attrition and greater weight loss success. These finding have implications for development of successful weight management programs in PCOS.

Dairy Intake Enhances Body Weight and Composition Changes during Energy Restriction in 18-50-Year-Old Adults-A Meta-Analysis of Randomized Controlled Trials

Background/Aims: A meta-analysis of randomized controlled trials (RCTs) was performed to investigate the effects of dairy food or supplements during energy restriction on body weight and composition in 18–50-year-old. Methods: RCTs ≥ 4 weeks comparing the effect of dairy consumption (whole food or supplements) with control diets lower in dairy during energy restriction on body weight, fat and lean mass were identified by searching MEDLINE, EMBASE, Pubmed, Cochrane Central and World Health Organization International Clinical Trials Registry Platform (WHO ICTRP) until March 2016. Reports were identified and critically appraised in duplicate. Data were pooled using random-effects meta-analysis. Chi²- and I²-statistics indicated heterogeneity. Dose effect was assessed using meta-regression analysis. GRADE guidelines were used to rate the quality (QR) of the evidence considering risk of bias, inconsistency, indirectness, imprecision, publication bias and effect estimates. Results: 27 RCTs were reviewed. Participants consumed between 2 and 4 standard servings/day of dairy food or 20–84 g/day of whey protein compared to low dairy control diets, over a median of 16 weeks. A greater reduction in body weight (−1.16 kg [−1.66, −0.66 kg], p < 0.001, I² = 11%, QR = high, n = 644) and body fat mass (−1.49 kg [−2.06, −0.92 kg], p < 0.001, I² = 21%, n = 521, QR = high) were found in studies largely including women (90% women). These effects were absent in studies that imposed resistance training (QR = low-moderate). Dairy intake resulted in smaller loss of lean mass (all trials pooled: 0.36 kg [0.01, 0.71 kg], p = 0.04, I² = 64%, n = 651, QR = moderate). No between study dose-response effects were seen. Conclusions: Increased dairy intake as part of energy restricted diets resulted in greater loss in bodyweight and fat mass while attenuating lean mass loss in 18–50-year-old adults. Further research in males is needed to investigate sex effects.

Effects of Low-Fat Diets Differing in Protein and Carbohydrate Content on Cardiometabolic Risk Factors during Weight Loss and Weight Maintenance in Obese Adults with Type 2 Diabetes

Despite evidence for the benefits of higher-protein (HP) diets in weight loss, their role in type 2 diabetes mellitus (T2DM) management and weight maintenance is not clear. This randomised study compared the effects of a HP diet (38% carbohydrate, 30% protein, 29% fat) to a isocaloric higher-carbohydrate diet (HC: 53%:21%:23%) on cardiometabolic risk factors for 12 weeks in energy restriction (~30% reduction) followed by 12 weeks of energy balance whilst performing regular exercise. Outcomes were measured at baseline and the end of each phase. Sixty-one overweight/obese adults (BMI (body mass index) 34.3 ± 5.1 kg/m², aged 55 ± 8 years) with T2DM who commenced the study were included in the intention-to-treat analysis including the 17 participants (HP n = 9, HC n = 8) who withdrew. Following weight loss (M ± SEM: −7.8 ± 0.6 kg), there were significant reductions in HbA1c (−1.4% ± 0.1%, p < 0.001) and several cardiometabolic health risk factors. Improvements were sustained for 12 weeks when weight was stabilised and weight loss maintained. Both the HP and HC dietary patterns with concurrent exercise may be effective strategies for weight loss and weight maintenance in T2DM although further studies are needed to determine the longer term effects of weight maintenance.

A telephone-supported cardiovascular lifestyle programme (CLIP) for lipid reduction and weight loss in general practice patients: a randomised controlled pilot trial

OBJECTIVE

To evaluate a primary prevention care model using telephone support delivered through an existing health call centre to general practitioner-referred patients at risk of developing CVD, using objective measures of CVD risk reduction and weight loss.

DESIGN

Participants were randomised into two groups: (i) those receiving a telephone-supported comprehensive lifestyle intervention programme (CLIP: written structured diet and exercise advice, plus seven telephone sessions with the Heart Foundation Health Information Service); and (ii) those receiving usual care from their general practitioner (control: written general lifestyle advice). Fasting plasma lipids, blood pressure, weight, waist circumference and height were assessed on general practice premises by a practice nurse at Weeks 0 and 12.

SETTING

Two general practices in Adelaide, South Australia.

SUBJECTS

Forty-nine men and women aged 48·0 (sd 5·88) years identified by their general practitioner as being at future risk of CVD (BMI = 33·13 (sd 5·39) kg/m2; LDL cholesterol (LDL-C) = 2·66 (sd 0·92) mmol/l).

RESULTS

CLIP participants demonstrated significantly greater reductions in LDL-C (estimated mean (EM) = 1·98 (se 0·17) mmol/l) and total cholesterol (EM = 3·61 (se 0·21) mmol/l) at Week 12 when compared with the control group (EM = 3·23 (se 0·18) mmol/l and EM = 4·77 (se 0·22) mmol/l, respectively). There were no significant treatment effects for systolic blood pressure (F(1,45) = 0·28, P = 0·60), diastolic blood pressure (F(1,43) = 0·52, P = 0·47), weight (F(1,42) = 3·63, P = 0·063) or waist circumference (F(1,43) = 0·32, P = 0·577).

CONCLUSIONS

In general practice patients, delivering CLIP through an existing telephone health service is effective in achieving reductions in LDL-C and total cholesterol. While CLIP may have potential for wider implementation to support primary prevention of CVD, longer-term cost-effectiveness data are warranted.

Effects of lifestyle modification in polycystic ovarian syndrome

Polycystic ovarian syndrome (PCOS) is a common endocrine condition with reproductive and metabolic consequences, including anovulation, infertility and an increased prevalence of diabetes mellitus. Obesity, central obesity and insulin resistance are strongly implicated in its aetiology. Dietary weight loss is recommended as the primary treatment strategy; however, effective means of achieving and maintaining weight loss and reproductive and metabolic improvements are unknown. Lifestyle modification programmes with an emphasis on behavioural management and dietary and exercise interventions have been successful in the general population in reducing the risk of diabetes and the metabolic syndrome, and have had some initial success in improving fertility outcomes in PCOS. However, the literature on effective diet and exercise programmes for PCOS has been sparse, and structured advice for implementing components of lifestyle modification programmes should be assessed in this population.

Gentamicin and penicillin in the treatment of severe respiratory infections

A combination of penicillin and gentamicin has been used for severely ill patients in a respiratory intensive care ward. It has been shown that predictable mean blood levels of gentamicin can be obtained in these patients by relating the dose to surface area (60 mg/m2/8 h). When renal function was initially normal it did not deteriorate during the course of therapy (10 days); gentamicin assays are not essential for safe treatment. In patients with renal failure, increasing the interval between doses also resulted in satisfactory levels, but close monitoring of the serum creatinine level is considered necessary. No clinical difference could be detected when gentamicin was given by constant or intermittent infusion.