Elsevier

Appetite

Volume 83, 1 December 2014, Pages 33-41
Appetite

Research report
Compliance to step count and vegetable serve recommendations mediates weight gain prevention in mid-age, premenopausal women. Findings of the 40-Something RCT

https://doi.org/10.1016/j.appet.2014.07.020Get rights and content

Highlights

  • The RCT evaluated a 12 month obesity prevention intervention in mid-age women.

  • Compliance to 10 diet and exercise recommendations was measured at three months.

  • Compliance scores were assessed in mediation models for 12 and 24 month weight loss.

  • Compliance to the 10,000 steps/day guideline mediated 12 and 24 month weight loss.

  • Compliance to the five vegetables serve/day guideline mediated 24 month weight loss.

Abstract

The 40-Something RCT aimed to determine if a 12-month health professional-led intervention could modify diet and physical activity behaviour for obesity prevention, in 44–50 year old, non-obese (BMI = 18.5–29.9 kg/m2) premenopausal women. Women were monitored for an additional 12 months to determine if effects could be maintained. This paper aimed to explore dietary and physical activity behavioural mediators hypothesised to be causally associated with weight change. Fifty-four women were randomised to a Motivational Interviewing Intervention (MI) (n = 28; five health professional consultations) or a Self-Directed Intervention (n = 26; written advice). Compliance to 10 study recommendations was measured at three months by a four-day weighed food and physical activity record including pedometer-measured step counts, self-reported exercise minutes and sitting time. The 10 compliance scores were independently assessed in mediation models for 12- and 24-month weight change. The MI effect on step count was an increase of 0.99 points on the 10-point compliance scale (p ≤ 0.01). This MI effect on step count significantly mediated the 12 and 24 month effect on weight (12 months AB = −0.74, 95%CI = −1.95, −0.14; 24 months AB = −1.06, 95% CI = −2.56, −0.36), accounting for 37.23% and 53.79% of the effect, respectively. The MI effect on vegetable serves was an increase of 1.50 points on the compliance scale (p = 0.02). The MI effect on vegetable compliance significantly mediated the effect on weight at 24 months (AB = −0.54, 95% CI = −1.50, −0.04), accounting for 24.92% of the effect. The remaining eight dietary and physical activity compliance scores did not significantly mediate weight loss. Encouraging women to take 10,000 steps and eat five vegetable serves per day may be a promising strategy to achieve long-term weight control at mid-life.

Introduction

In the last few decades, there has been a strong interest in effective weight gain prevention strategies to combat rising obesity prevalence (Armstrong et al, 2011, Brown et al, 2009, Cavill et al, 2012, Franz et al, 2007, Greaves et al, 2011, Neve et al, 2010, Young et al, 2012). Not surprisingly, the worldwide weight gain trend correlates with decreasing levels of adherence to population diet and physical activity recommendations (Australian Bureau of Statistics, 2009, King et al, 2009). Behavioural treatments that incorporate diet and physical activity lifestyle changes are recommended for weight control interventions (Dietitians Association of Australia, 2005, Lau et al, 2007, Tsigos et al, 2008). Weight loss interventions have had small yet clinically important effects (Franz et al, 2007, Greaves et al, 2011, Neve et al, 2010, Young et al, 2012); however, few interventions have been successful in facilitating weight loss beyond two years (Barte et al., 2010).

In addition to evaluating whether an intervention is effective, it has been recognised that understanding how interventions achieve their results is important (Baranowski, 2006). Understanding how ‘successful’ intervention participants achieve weight loss provides insight into effective weight control treatment (Teixeira et al., 2009). Mediation analysis is emerging as an important statistical tool in weight loss research as it provides evidence on the mechanism of change in a behavioural intervention (Lockwood, DeFrancesco, Elliot, Beresford, & Toobert, 2010). This provides an opportunity for researchers to understand associations between complying with diet, physical activity and sedentary behaviour recommendations and achieving weight loss (Lubans et al., 2012). Determining which intervention recommendations are more effective will enable the development and refinement of more targeted weight management programs (Hultquist et al, 2005, Swinburn et al, 2004) and will enable researchers to modify intervention resources to support recommendations that are associated with weight loss success (Teixeira et al., 2009).

The ‘40-Something’ Randomised Controlled Trial (RCT) aimed to determine whether a 12-month health professional-led intervention, employing motivational interviewing as the counselling framework, could result in diet and physical activity behaviour change for weight control in non-obese, premenopausal mid-age women (Williams, Hollis, Collins, & Morgan, 2013). Weight gain prevention advice for all participants was based on 10 weight control recommendations. Seven recommendations related to dietary intake for vegetable, fruit, meat, dairy, wholegrains and extra (non-discretionary food) serves as well as the number of meals eaten outside the home. Two recommendations related to physical activity for minutes of moderate-to-vigorous physical activity and step count, and one to sedentary behaviour (Box 1). This paper aimed to examine whether compliance to the 10 weight control recommendations of the 40-Something study significantly mediated the long-term effect of the intervention on weight loss at 12 and 24 months. The 40-Something study methods paper (Williams et al., 2013) and the 12-month weight outcomes paper (which also presents the waist circumference, percentage body fat, percentage lean muscle mass, blood cholesterol level, fasting glucose and blood pressure findings) (Williams, Hollis, Collins, & Morgan, 2014) have been published. This paper presents the findings from our mediation analysis to determine how successful intervention women achieved weight gain prevention and provides evidence of the mechanism of behaviour change.

The 10 weight control recommendations provided to both Motivational Interviewing and Self-Directed Intervention participants.

  • 1.

    Aim to eat at least 2 serves of fruit every day, where 1 serve is 1 medium piece of fruit, 2 small pieces of fruit, 1½ tablespoons of sultanas, 4 dried apricot halves or ½ cup fruit juice.

  • 2.

    Aim to eat at least 5 serves of vegetables every day, where 1 serve is ½ cup cooked vegetables or 1 cup raw salad vegetables.

  • 3.

    Aim to eat 1–1½ serves of meat or meat alternatives every day, where 1 serve is 65–100 g cooked meat or chicken, 120 g cooked fish fillet, 2 eggs, ½ cup cooked beans, lentils, chickpeas or canned beans, 1/3 cup nuts or ¼ cup sunflower seeds or sesame seeds.

  • 4.

    Aim to eat 2–3 serves dairy every day, where 1 serve is 250 ml milk (fresh or long life cow milk or soy milk), 125 ml evaporated milk, 200 g yoghurt, 40 g cheese or 2 slices pre-sliced cheese.

  • 5.

    Aim to eat wholegrain varieties of breads and cereal. Wholegrain varieties are recommended as they may assist in avoiding weight gain.

  • 6.

    Limit your intake of extra foods which are high in fat and sugar, to 2 serves per day (or 1.5 for weight loss) or less. One serve of extra food is 1 doughnut, or 4 plain sweet biscuits, 1 slice of cake, ½ small chocolate bar, 2 tablespoons cream or mayonnaise, 1 tablespoon of oil, butter or margarine, 200 ml wine or 60 ml spirits, 600 ml light beer, 400 ml beer, 1 can of soft drink, 1 small packet crisps, 2/3 slice of pizza, 1/3 meat pie or pastry, 12 hot chips or 1½ scoops ice-cream.

  • 7.

    Aim to cut down on the number of meals eaten outside the home each week, as these foods are often higher in fat, sugar and salt.

  • 8.

    Aim to engage in moderate to vigorous physical activity for 150 minutes (or 250 minutes for weight loss) total per week. Activities may include brisk walking, jogging, exercise classes, sports, swimming, dancing, cycling or vigorous household chores.

  • 9.

    Aim to sit for less than 3 hours each day.

  • 10.

    Aim to walk 10,000 steps per day by being active in as many ways as possible. Try walking to work, taking the stairs instead of the lift, walking to the shops for your newspaper or milk on the weekend or challenging family and friends to be active with you.

Section snippets

Methods

The detailed methods of the 12-month parallel-group 40-Something RCT have been reported elsewhere (Williams et al., 2013). Briefly, non-obese pre-menopausal, healthy women aged 44–50 years were stratified by BMI group (18.5–24.9 kg/m2 and 25–29.9 kg/m2) then randomised using a computer generated allocation sequence to one of two study arms: (i) Motivational Interviewing Intervention (MI) or the (ii) Self-Directed Intervention (SDI) (Fig. 1). The study received institutional review and approval

Results

Fifty-four women met the inclusion criteria and were enrolled (Fig. 1) with 28 randomised to MI and 26 to SDI group. The women had a mean (SD) age of 47.3 (1.8) years, a weight of 68.7 (7.9) kg, BMI of 25.1 (2.4) kg/m2 and percent body fat of 35.8 (5.6) % (Table 2). Ninety-one percent, 74% and 56% of the participants were retained at 3-, 12- and 24 months respectively. Two women completed the 3-month weight measurement but not the 3-month diet and physical activity measurements, giving a

Discussion

This paper has revealed the potential dietary and physical activity behavioural mediators causally related to weight change at 12 and 24 months in healthy weight and overweight premenopausal women participating in the 40-Something RCT. The findings from the main analysis using the imputation mediation model (Table 4) are primarily consistent with the sensitivity analysis mediation model using LOCF (Table S1). In both analyses, increased compliance to the 10,000 step count recommendation by the

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  • Cited by (0)

    Acknowledgements: This study formed part of JLH's doctoral studies conducted under the supervision of LTW, CEC and PJM at the University of Newcastle, Australia. JLH is supported by an Australian Postgraduate Award Scholarship and a Barker Top-up Scholarship from the Barker Family, University of Newcastle and University Foundation Services. The authors wish to acknowledge Kathryn McQualter for her valuable contribution to the study as part of the Nutrition and Dietetics Embedded Honours program at the University of Newcastle. Finally, the authors wish to thank the 40-Something study participants for their involvement. Conflict of interest: The authors declare that they have no competing interests. Authors' contributions: All authors contributed to the interpretation of the results and the drafting and revision of this manuscript. JLH, LTW, CEC and PJM were responsible for the design of the study. JLH completed the literature review, data entry, calculated the compliance score and drafted the initial paper. LTW, KTP and JLH developed the compliance scoring system. MDY conducted the statistical analysis.

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