Weight loss maintenance in women 3 years after following a 12-week structured weight loss program

Obesity Research & Clinical Practice (2007) 1, 195—211

ORIGINAL ARTICLE

Weight loss maintenance in women 3 years after following a 12-week structured weight loss program Xenia Cleanthous, Manny Noakes ∗, Jennifer B. Keogh, Philip Mohr, Peter M. Clifton Commonwealth Scientific and Industrial Research Organisation (CSIRO) Human Nutrition, Adelaide, South Australia 5000, Australia Received 24 August 2006 ; received in revised form 16 March 2007; accepted 6 July 2007

KEYWORDS Obesity; Weight loss maintenance; Long-term; Structured weight loss program; Whole foods

Summary Structured weight loss programs such as those using meal replacements are associated with both short-term and long-term weight loss, but the effectiveness of structured weight loss programs using whole foods has not been established. The primary aim of the present study was to retrospectively establish self-reported weight status in women, 3 years after participation in a 12-week food based structured weight loss program monitored by dietitians. The secondary aim was to determine which factors were associated with successful weight loss maintenance. Eighty-five of the 100 participants who completed the 12-week program participated in an 18-question telephone interview which included self-reported weight. Weight loss from baseline was 3.8 (S.D. 5.5) kg (4.4 (S.D. 6.1) %) (P < 0.001). Overall, 61% of participants weighed less than at baseline, 13% had gained weight, and the remaining 26% had maintained their baseline weight. From baseline, 37 (44%) participants had a clinically important weight loss of ≥ 5%, and were, on average, 9.8 (S.D. 4.2) % lighter (P < 0.001). The remaining 48 (56%) participants (weight loss < 5%) were not significantly different to their weight at baseline (P = 0.77). We conclude that a food based structured weight loss program monitored by dietitians, as defined by this intervention, was associated with long-term weight loss maintenance. Crown Copyright © 2007 Published by Elsevier Ltd on behalf of Asian Oceanian Association for the Study of Obesity. All rights reserved.

∗ Corresponding author at: CSIRO Human Nutrition, Gate 13 Kintore Avenue, PO Box 10041, Adelaide BC, South Australia 5000, Australia. Tel.: +61 8 8303 8827; fax: +61 8 8303 8899. E-mail address: [email protected] (M. Noakes).

1871-403X/$ — see front matter Crown Copyright © 2007 Published by Elsevier Ltd on behalf of Asian Oceanian Association for the Study of Obesity. All rights reserved.

doi:10.1016/j.orcp.2007.07.002

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Introduction Obesity is a major public health issue in Australia, with an estimated one fifth of Australian men (19%) and women (22%) now classified as obese [1], according to the World Health Organisation definition of a body mass index (BMI) ≥ 30 kg/m2 [2]. It places a large burden on the Australian healthcare system, costing an annual $830 million [3]. Structured weight loss programs currently form one of the key treatments of obesity. They often incorporate use of very low calorie diets or partial meal replacements. Current evidence supports that this approach can be effective in achieving weight loss of up to 9—10% in the short-term (3—12 months) [4—7]. In the long-term (≥12 months), use of meal replacements in this context can also be beneficial for maintaining up to a 6—8% weight loss [4,7,8]. Evidence supports that food based structured weight loss programs can be as effective as meal replacement strategies, and it has previously been shown that these programs can achieve a 9% weight loss in the short-term (6 months) [6]. Similarly, participants in the Diabetes Prevention Program (DPP), who were provided with specific dietary information according to national guidelines, achieved an approximate 7% weight loss over 6 months [9]. Population-based studies also support that those who successfully maintain short-term weight loss often have structured meal patterns [10—12] and a reduction in the variety of foods consumed within their diets [13]. The long-term effectiveness of these programs, however, remains unclear. Some have suggested an increased risk of, or actual, weight gain following their completion [14], resulting in the loss of the positive psychological effects of weight reduction [15]. Such outcomes may then perpetuate continued episodes of weight cycling, in which the repeated loss and regain of weight over time can lead to further reductions in psychological wellbeing and negative metabolic effects [15—17]. A sustained weight loss produces many health benefits, particularly in those with metabolic diseases such as Cardiovascular Disease, Type II Diabetes and Poly-Cystic Ovarian Syndrome [18—22]. Given this, it is very important to understand what helps people successfully maintain long-term weight loss, the potential role that food based structured weight loss programs play in this, and what the potential triggers for weight regain might be. The primary aim of the present study was to retrospectively establish self-reported weight status in women, 3 years after participation in a 12-week food based structured weight loss program mon-

Figure 1 Schematic representation of study design.

itored by dietitians. The secondary aim was to determine which factors were associated with successful weight loss maintenance. We hypothesised that those who successfully maintained long-term weight loss would exhibit different characteristics to those who did not.

Participants and methods For the original study [23] women were recruited by public advertisement. Inclusion criteria were female 20—65 years, BMI 27—40 kg/m2 , no history of metabolic disease or Type 1 or Type 2 Diabetes. One hundred and nineteen women participated, 19 of whom withdrew from the study before completion (Fig. 1). The study was a parallel design with participants randomized to one of two isocaloric 5600 kJ dietary interventions (high protein (HP) or high carbohydrate (HC)) of 12 weeks duration. The planned macronutrient profile for the HP diet was 34% and 46% energy from protein and carbohydrate, respectively, and 20% energy from fat (<10% saturated fat energy): for the HC diet it was 17% and 64% energy from protein and carbohydrate, respectively, and 20% energy from fat (<10% saturated fat energy). Every 4 weeks, study participants were interviewed individually by one of two qualified dietitians, who conducted all dietary counseling and instructed on dietary requirements, including advice on specific food quantities and provision of a menu plan. Participants were also required to selfmonitor food intake using a daily checklist, and to complete fortnightly 3-day weighed food records, which were then used to assess compliance. They attended the Clinical Research Unit fortnightly, and were supplied with key foods consistent with their allocated diet. Food preparation sessions specific to the diet protocol were also conducted by a home economist every 4 weeks for each diet group and recipes provided. The total energy content of each diet was initially 5600 kJ for all participants with some

Weight loss maintenance adjustment upwards for those who were very active, so that weight loss would approximate 1 kg per week for the first 2—3 weeks. The fibre content and fatty acid profile was planned to be the same between diets. Physical activity advice was consistent with recommendations to increase physical activity to at least 30 min three times per week and to document these occasions in their daily checklist. [23]. Participants were followed-up tri-monthly for 12 months following completion of the original 12week program. This included a fasting visit to the clinic at which their weight was taken, but no dietary or other support by the Clinical Research Unit was provided. At 3 years, of the 100 participants in the original program [23], 10 could not be contacted during the specified period, and 3 were contacted but did not want to participate. This left a total 87 participants, aged 33—68 years, who agreed to take part in the interview (Fig. 1). For these, consent was obtained to send an information letter in the mail, providing details about the study. Each participant was subsequently telephoned during a 3-week period over July—August 2005 to obtain informed, verbal, consent for the study, and to participate in the 10—15 min interview. Ethics approval was obtained prior to commencing the study from the Commonwealth Scientific and Industrial Research Organisation (CSIRO) Human Nutrition Human Ethics Committee (Approval Number 05/09) and all women who participated gave informed consent.

Interview schedule To ensure consistency, interviews followed a standard format, and were conducted by one investigator for the whole sample. The study was conducted by telephone in order to minimize the burden on the volunteers and to maximise their participation. As little is currently known about the factors that influence long-term weight status, the setresponse questions used in our interview were based on factors associated with short-term weight status. These factors included weight loss history and weight loss methods, meal patterns, self-monitoring behaviours and physical activity habits [10—12,24,25]. Other questions addressed the psychological effects associated with long-term weight status, as improvements are thought to be related to successful weight loss, and viceversa [10,15—17,26]. Open-ended questions were employed to identify any unanticipated factors that may influence long-term weight status.

197 The interview contained a series of 18 structured questions (Appendix A), which was divided into four sections: (a) weight history and dietary patterns, (b) exercise habits, (c) perceived effects of weight status on psychological wellbeing, and, (d) influences on weight status and potential triggers for weight regain. The methods used to investigate these parameters is described below: Weight history and dietary patterns Where possible, participants were asked to weigh themselves during the telephone interview and indicate their current weight. This value was used to calculate their current BMI (kg/m2 ). Their current weight was also used to calculate their change in body weight since commencement and since completion of the program, expressed as both a percentage (%), and as absolute weight (kg). To determine weight loss history and frequency of dieting, participants were asked how many times in their life they had intentionally lost weight (‘frequency of weight loss’), and how often they were trying to lose weight (‘frequency of weight loss attempts’), respectively. For analysis, number of times of intentional weight loss was categorized into <5, 5—10 and >10 times. Frequency of dieting was categorized into 0—1, 2—6, 7—11 and 12 months per year. Participants were also asked about their current action in relation to their weight status using a series of closed questions. To determine their current eating behaviours, participants were asked about their daily dietary patterns relating to meals and meal times. Weight loss methods were investigated through a series of statements about various approaches used to alter dietary intake. Exercise habits Exercise habits were assessed using the validated Paffenbarger Physical Activity Questionnaire [27]. Total flights of stairs climbed, total blocks walked, and the frequency, duration, and intensity level of each sport/recreational activity were used to estimate the weekly average energy expended (kJ). Intensity level was defined according to metabolic equivalents (METS), where light, moderate and vigorous intensity activities were defined as those with METS <3, 3—6, and >6, respectively [28]. For analysis, energy expended from stairs climbed and blocks walked was combined as ‘incidental activity.’ Perceived effects of weight status on psychological wellbeing Participants were asked whether, and how, time spent thinking about food and weight had changed since they completed the program. They were also

198 asked whether, and how, weight status affected their self-esteem/confidence and general mood. Participants rated their thoughts on the impact of participation in a food based structured weight loss program on their overall psychological health and wellbeing, using a ten-point scale (1 = very detrimental, 10 = very beneficial). Influences on weight status and potential triggers for weight regain To investigate the influence of self-monitoring, participants were asked about their frequency of weighing (number of times per week), which was then categorized into <1 and ≥1 time(s) per week for analysis. Potential triggers for weight regain were investigated through a series of statements about various physical, emotional and lifestyle factors that may influence this. Participants were also asked to convey any factors they believe help promote successful weight maintenance, or any that make it more difficult. These responses were then coded according to common themes by one investigator. To compare the ease of weight loss to weight loss maintenance, a seven-point Likert-like scale (1 = extremely easy, 7 = extremely difficult) was used.

Statistical analysis To account for day-to-day variability, those participants who were currently within 2% of their weight when they began the program (i.e. at baseline) were identified as being weight stable. The remainder were identified as having a net weight gain, or loss, as appropriate. For between-group comparisons, participants were classified either as ‘weight loss maintainers’ (WLMs) or ‘weight loss regainers’ (WLRs). Given the health benefits of a net 5% weight loss [18,19], WLMs were defined as those who had a net weight loss ≥5% since baseline. WLRs were those who had a net weight loss < 5% since baseline, thereby also encompassing those who had a net weight gain or remained weight stable. Normally distributed variables were described using mean values and standard deviations (S.D.). Non-normally distributed variables were described using median values and range (minimum and maximum). Between-group comparisons (WLMs versus WLRs) for weight variables, age and BMI were made through independent-sample t tests, and through Mann—Whitney U tests for physical activity variables. Within-group comparisons for weight variables were made through paired t tests. Between-group comparisons for dietary patterns, weight history, frequency of weighing, and,

X. Cleanthous et al. effect of weight status on psychological wellbeing were made though ␹2 tests. The relationship between absolute weight change during the program and absolute long-term weight change (i.e. from baseline to 3 years), was determined by Pearson correlation (r). Statistical analysis was performed using the software package SPSS for Windows, Version 11.5 (SPSS Inc., Chicago, 2002). P-values are reported where statistical analysis was conducted and sample size permitted. A P-value less than 0.05 was considered statistically significant.

Results (3 year follow-up) Fasting baseline weight was measured at the clinic facility and compared to participants’ self reported weight as documented on their medical questionnaire prior to participation in the study. On average, their self-reported weight was 1.0 (S.D. 2.9) kg (1.1 (S.D. 3.4) %) less than their measured fasting screening weight (P = 0.001) (data not shown). Time course of weight loss change is shown in Fig. 2. Since baseline, participants had a mean net weight loss of 3.8 (S.D. 5.5) kg (4.4 (S.D. 6.10) %) (P < 0.001) (Fig. 3). By our definition, 61% of participants had a net weight loss, and 26% remained weight stable. The remaining participants had a net weight gain. Absolute weight change during the program was positively correlated with long-term absolute weight change (i.e. from baseline to 3 years), with a trend towards significance [r = 0.20, P = 0.060].

Figure 2 Mean (±S.E.M.) weight of sub-sample (n 66) over time, according to weight status (weight loss maintainer or weight loss regainer). *Significantly different from 12 weeks (3 months), P < 0.001, **Significantly different from 12 weeks (3 months), P = 0.047. † Significantly different from 15 months following start of program, P = 0.006.

Weight loss maintenance

199

Figure 3 Mean (±S.E.M.) weight of all participants (n 85) over time. *Significantly different from baseline, P < 0.001.

Of the final 87 participants, two were later excluded from any between-group comparisons, as they were unable to quantify their current weight and therefore could not be classified as WLMs or WLRs. By the definition used, there were 37 WLMs and 48 WLRs within the sample (total n 85). WLMs currently weighed a mean 78.6 (S.D. 12.8) kg, which was 9.8 (S.D. 4.2) % less than their weight at baseline (P < 0.001). WLRs currently weighed a mean 84.8 (S.D. 9.3) kg, which was not significantly different to their weight at baseline (P = 0.77) (Table 1, Fig. 4). No significant association was found between WLM versus WLR status for diet allocation in the program (P = 0.42), nor for their current action in relation to their weight status (P = 0.10) (data not shown). Sixty-eight percent of WLMs reported that they were actively trying to lose or maintain their current weight, whereas the majority of WLRs (50%) reported wanting to lose weight but had not taken the actions to do so (data not shown).

Weight history No significant association was found between WLM versus WLR status and frequency of weight loss Table 1

a c

(P = 0.70) or frequency of weight loss attempts (dieting) (P = 0.16) (data not shown).

Dietary patterns The majority of both WLMs (87%) and WLRs (92%) reported consuming breakfast every day. Most also reported consuming lunch (84% WLMs, 85% WLRs) and dinner (95% WLMs, 98% WLRs) every day. Almost all WLMs (89%) and WLRs (90%) reported consuming take-away or fast food ≤1 episode/week, as was the case for frequency of dining-out (95% WLMs, 92% WLRs). Approximately half of WLMs (54%) and WLRs (52%) reported snacking ≤1 episode/day. The majority of participants reported not having a set meal pattern only ≤1 day/week, (78% WLMs, 85% WLRs) and eating at the same time(s) on ≥5 out of 7 days (87% WLMs, 94% WLRs).

Subject characteristics at 3-year follow-up

Age (y) Weight (kg) BMI (kg/m2 ) b

Figure 4 Mean (±S.E.M.) weight of participants (n 85) over time, according to weight status (Weight Loss Maintainer or Weight Loss Regainer). *Significantly different from baseline, P < 0.001. † Significantly different from 12 weeks, P < 0.001.

Total (n 85)

Weight loss maintainersa (n 37)

Weight loss regainersb (n 48)

Mean

S.D.

Mean

S.D.

Mean

S.D.

53 82.1 31.3

10 11.3 3.8

53 78.6 29.6

9 12.8 3.8

53 84.8 32.6

10 9.3 3.4

Net weight loss a 5% since baseline. Net weight loss < 5% since baseline. Weight loss maintainers vs. weight loss regainers.

Pc

0.98 0.016 <0.001

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Figure 5 Weight loss methods currently or previously used by participants (n 56) since completing the program. Some participants provided more than one response. Table 2 Energy expenditure of participants from incidental activity and from sports/recreational activites of varying intensities (kJ/week)

Energy expended from incidental activities (stairs climbed + blocks walked) Energy expended from low intensity activities Energy expended from moderate intensity activities Energy expended from high intensity activities Total energy expended (incidental and activities) a b

Weight loss maintainers (n 37)

Weight loss regainers (n 48)

Median

Median

1873a

Range 42—8427

1873b

P

Range 42—10,300

0.94

0

0—4036

0

0—1853

0.58

941

0—9932

0

0—15,456

0.51

0—19,228

0

0—33356

0.35

0 5590a

702—28,595

5333b

936—37,082

0.89

n 31 as three were unable to quantify this. n 47 as one participant was unable to quantify this.

were ‘commercial weight loss programs’ or using the ‘Total Wellbeing Diet meal plan’ (Fig. 5).

Weight loss methods Thirty percent of WLMs and 38% of WLRs reported that they did not use, or were not currently using, any weight loss method since completing the program. Of the WLMs who reported doing so, the most common methods were ‘dieting by reducing overall intake’ and ‘commercial weight loss programs.’ Amongst WLRs, the most common methods

Physical activity No significant differences were observed between WLMs and WLRs for any of the physical activity variables tested (Tables 2 and 3). Most people did not participate in low-intensity (87% WLMs,

Table 3 Exercise patterns of those who participated in a sport/recreational activity(ies) on a regular basis during the past year

Energy expended from activity(ies) (kJ/week) Duration of exercise per episode (minutes/day) Frequency of activity participation (no. times/week)

Weight loss maintainers (n 24)

Weight loss regainers (n 26)

P

Median

Range

Median

Range

4606

772—20,169

4343

549—35,210

0.94

33

4—96

30

4—149

0.72

6

1—28

5

1—36

0.95

Weight loss maintenance 90% WLRs) or high-intensity (73% WLMs, 81% WLRs) activities, so the modal, and therefore, median energy expenditure for both these series of activities was 0 kJ/week (Table 2). Twelve percent more WLMs than WLRs reported participating in moderate intensity activities but the median 941 kJ/week energy expended by WLMs from moderate intensity activities, compared to the median 0 kJ/week expended by WLRs was not significantly different (P = 0.51) (Table 2). Overall, 46% of WLRs reported not participating in any sport/recreational activities, compared to 35% of WLMs. Both groups reported exercising a median of approximately 30 min, five (WLRs) to six (WLMs) times a week (Table 3). For those who reported participating in one or more activities, walking was most common (71% WLMs (n 17), 81% WLRs (n 21)) (data not shown).

Perceived effects of weight status on psychological wellbeing Fifty-seven percent of WLMs, and 52% of WLRs reported that the time spent thinking about food had increased since they completed the program, and most others (41% WLMs, 40% WLRs) reported that this had remained unchanged. Only 1 WLM and 4 WLRs reported a decrease. Similar proportions of WLMs and WLRs reported that the time spent thinking about weight had increased (32% WLMs, 54% WLRs), or remained unchanged (46% WLMs, 44% WLRs) since they completed the program. Only 2 WLMs and 2 WLRs reported a decrease. The majority of both WLMs (84%) and WLRs (85%) reported that weight status is reflected in their self-esteem/confidence and slightly lower numbers of WLMs (78%) and WLRs (75%) reported that

201 their weight status is reflected in their general mood. On the scale of 1—10 (1 = very detrimental, 10 = very beneficial), both WLMs and WLRs, on average, felt the program was quite beneficial to their current psychological wellbeing (8.2 (S.D. 1.7) versus 8.1 (S.D. 1.5), respectively), which was not significantly different between groups (P = 0.74).

Influences on weight status and potential triggers for weight regain No significant association was found between WLM versus WLR status and frequency of weighing (P = 0.61), with 51% WLMs and 46% WLRs reporting weighing themselves at least once a week (data not shown). Fifty-five participants perceived themselves to have regained weight following completion of the program. The most commonly reported perceived triggers for this were ‘emotionally related adverse life-events,’ ‘lifestyle influences (job, home),’ and, ‘development of an injury/physical condition that made exercise difficult’ (Fig. 6). Of these 55 participants, 22% reported that they could not identify any significant trigger(s) for their perceived weight gain (Fig. 6). No significant difference was observed in the rating of the ease of weight loss (compared to weight maintenance) between WLMs and WLRs (P = 0.62). Based on the scale used, both WLMs (3.5 (S.D. 2.1)) and WLRs (3.7 (S.D. 2.3)) felt it was slightly easier to lose weight than maintain it, on average. Key aspects perceived to promote or hinder successful weight maintenance included a combination of internal and external factors. Seventy-nine participants commented on positive influences, although no significant associations between WLM

Figure 6 Perceived triggers for weight regain since completing the program (n 55). Some participants provided more than one response. *Other is comprised of 8 other factors (development of medical condition related to weight gain, commencing medication with weight gain as a side effect, decrease in exercise, dissatisfaction with study meal plan, pre/post pregnancy, lack of support following completion of the program, development of illness, limited time for food preparation).

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Table 4

Factors that help promote successful weight maintenance Number of participants (n 79)a

Program-related, e.g. counselling sessions, food diary, weigh-in’s, structured eating plan Feeling the physical benefits of maintaining a stable weight Having a good knowledge of principles of healthy eating/cooking Feeling the psychological benefits of maintaining a stable weight Having a positive attitude/self-encouragement Having self-discipline/willpower Being aware of what you are eating Combination of exercise and healthy eating principles Having encouragement from others Otherb a b

Weight loss maintainers (n 35)

Weight loss regainers (n 44)

22

30

9

4

8

4

7

3

5 5 4 3

8 5 5 10

3 13

6 13

Some participants provided more than one response. Other is comprised of 8 other factors for weight loss maintainers, and 7 other factors for weight loss regainers.

versus WLR status were found for any of them. Of this sample, 60% of WLMs and 63% of WLRs reported on ‘components of the structured weight loss program,’ such as having dietary counseling, food diaries, and frequent weigh-ins (Table 4). Psychological aspects of weight maintenance, such as a ‘positive attitude,’ ‘willpower,’ and ‘feeling the psychological benefits,’ were also common themes among both groups. Many in both groups also reported positive lifestyle aspects of weight maintenance, including factors such as ‘healthy eating,’ ‘physical activity’ and ‘feeling the physical benefits.’ Eighty participants commented on positive influences, although no significant associations between WLM versus WLR status were found for any of Table 5

them (data not shown). Seven of this sample reported that there were ‘no factors’ that make this the case (Table 5). The two most common factors for both groups were a ‘lack of selfdiscipline/willpower’ and ‘social occasions relating to food.’ Other key factors included ‘being in an environment influenced by others,’ and a ‘lack of external support/encouragement.’ Of this sample, some WLMs (11%) and WLRs (13%) also reported that ‘emotionally related events’ may negatively impact successful weight maintenance.

Subgroup analysis (12-month follow-up) Of those for which there was complete data available at all time points (n 66), there were 28 WLMs

Factors that make successful weight maintenance difficult to achieve Number of participants (n = 80)a Weight loss maintainers (n 35)

Lack of self-discipline/willpower Social occasions relating to food Lack of support/encouragement Having to cater for other’s dietary needs/living with others Emotionally related events None Lack of time to prepare healthy meals and/or incorporate physical activity Otherb a b

Weight loss regainers (n 45)

9 8 7 6

14 10 4 9

4 3 2

6 4 5

12

16

Some participants provided more than one response. Other is comprised of 7 other factors for weight loss maintainers, and 8 other factors for weight loss regainers.

Weight loss maintenance and 38 WLRs, who did not differ in baseline weight (P = 0.55). At 12 months following completion of the program, WLRs gained 4.2 (S.D. 3.3) kg (5.4%) (P < 0.0001). At 3 years (39 months) they also gained a further 2.3 (S.D. 4.8) kg (3.0%) (P = 0.006). Three months following completion of the program, WLMs lost a further 1.2 (S.D. 3.0) kg (1.3%) (P = 0.047). (Fig. 2).

Discussion Three years after completing the program, participants maintained an approximate 4% net weight loss, which was also observed in the lifestyle intervention of the DPP [9] — one of the few major long-term studies using whole foods. This intervention also included a specific exercise component, in conjunction with a detailed education program about diet, exercise and behaviour modification [9]. Despite this, long-term weight loss remained comparable to that observed in our study, suggesting that the use of whole foods in its own right promotes long-term weight loss maintenance. Overall, nearly two thirds (61%) of participants in our study maintained a net weight loss, and 44% of participants successfully maintained a clinically important weight loss. Given that an estimated 80% of obese patients who have undergone pharmacological and/or behavioural weight-loss therapy return to, or exceed their pre-treatment weight 3—5 years post-treatment [29], our results are quite promising. Also, a net weight loss of around 3% can still improve health outcomes, such as cardiovascular disease risk factors [21]. Contrary to previous findings [14,30], weight cycling did not appear to be a risk factor for weight regain, since frequency of previous weight loss episodes was not significantly different between groups. Our finding that a greater initial weight loss is positively correlated to better a long-term outcome is also supported by other studies [31,32]. Having participated in the program, WLRs appeared to be no worse off (psychologically), and they actually reported benefits to their psychological wellbeing, which is also confirmed by previous studies [33,34]. Since the participants also completed the program with an increased knowledge of healthy eating and cooking principles, this indicates that it was still beneficial to all participants, but more so for some than others. Some suggest that regular meal patterns including breakfast, infrequent dining-out, reduced fast food consumption, and, frequency of snacking are associated with long-term weight mainte-

203 nance [35—38], however, none of these practices appeared to differentiate between the two groups in our study. Since frequency of dieting was not significantly different between groups, nor was the amount of weight lost during the program, this implies that one group was not necessarily more successful than the other at actually achieving weight loss. As WLMs felt it was slightly easier to lose weight than to maintain it, and the majority of them were actively doing something about their current weight, they may have a greater understanding of the need for continued monitoring of weight and of energy intake and/or expenditure, required for successful weight loss maintenance [11,39]. Some of these self-monitoring behaviours include frequent weighing and a continued awareness of weight and food intake [11], however these particular factors did not differentiate WLMs and WLRs. This may be because the WLMs who reported an increase in time spent thinking about food and/or weight, did so because they became more aware of these components. For WLRs, this increase may have been detrimental, as they became more preoccupied with their weight and/or food intake, but not necessarily more aware. Both groups would therefore have seen an increase in these variables but with different implications. Since a large proportion of participants reported that their weight regain was attributed to an emotionally related life event, and many also commented that emotional influences make it difficult to maintain weight, these participants may tend to use food or eating to moderate negative mood states [40]. The susceptibility to external influences was also reflected by comments that the home and other environments, including social occasions, were a trigger for weight regain, or make it difficult to prevent. This may be attributed to these participants’ potential lack of internal control over eating behaviour, as exemplified by their self-reported ‘lack of willpower/self-discipline,’ possibly arising from an absence of the knowledge and skills needed to cope with adverse situations, in combination with a lack of motivation to achieve this. From the participants’ comments, it appeared that for optimal weight loss maintenance, an absence of negative external influences in combination with a presence of positive external influences such as those provided by the program was required for weight control. For the sub-sample, despite both groups being able to sustain their weight loss in the short-term (6 months following completion of the program), the WLRs were not able to achieve this in the

204 long-term. This suggests that only selected individuals may require the continual presence of positive external influences (such as those provided by the program) to successfully maintain long-term weight loss. The findings that the sub-sample WLMs continued to lose weight for the 3 months following the program’s completion lends support for this explanation. Although physical activity has been implicated in successful weight maintenance [11,12,25], our findings did not indicate this was the case, which may be because the levels required to do so are often much greater than the levels reported by our participants. Compared to the conventional recommendation of 4200 kJ/week, an energy expenditure of >10 500 kJ/week, has been shown to improve long-term weight loss [41] as supported by a study of successful female weight loss maintainers, who reported expending an estimated 11 200 kJ/week [10]. During our program, participants were recommended to do ≥30 min of physical activity 3 times a week [23], which appeared to carry through to their current levels of 150—180 min/week. This amount of physical activity can produce health benefits, such as a reduced risk of developing type II diabetes and other lifestyle diseases [42], but for successful weight loss maintenance, >200 min/week of physical activity is now required [42]. Since some participants reported that a reduced level of physical activity was a trigger for their weight regain, and others reported that exercise was important for successful long-term weight maintenance, this suggests they may have had some knowledge about the relationship between physical activity and weight status, but were not motivated enough to regularly carry it out.

Future directions Participants in weight loss programs eating a diet of conventional foods are thought to underestimate their intake by 30—50% [43], whereas those provided with a structured meal plan, as in our study, have better long-term outcomes [44,45]. Also, in the development of weight loss goals for these programs, our finding that a greater initial weight loss is positively correlated to better a long-term outcome, as confirmed by other studies [46,47], should be considered.

Strengths and limitations of the study We acknowledge that the results obtained from this study only allow us to draw conclusions about factors associated with successful weight loss maintenance. Determination of predictive factors to

X. Cleanthous et al. identify causality would require a different study design than was possible. It is also unknown whether the 13 non-respondents differed in their characteristics, although there was a high response rate of 87%. Although the sub-sample analysis is limited to 12 months and does not include the total sample, our classification system using ‘WLMs’ and ‘WLRs’ was consistent in this group — at 12 months following completion of the program, the WLMs sustained their weight, whereas WLRs did not, and this trend was also reflected in their respective weights at 3 years. Evidence suggests that self-reported weight can be unreliable in the overweight and obese populations [44], this did not appear to be as evident in this study. The 1% disparity observed at baseline may have been contributed to by day-to-day variation, for which we allowed 2%, and it may also be explained by differences in the participants’ fasting status, as their baseline measured weight was fasting, whereas baseline self-reported weight was not. To reduce reporting bias, telephone contact was made with participants, which allowed for clarification of responses, especially by prompting each participant to weigh themselves during the interview. Given the retrospective nature of the study, our results may have been subject to recall bias, and the use of a select group of participants who were motivated to take part in a structured weight loss program, restricts the generalisability of our findings. In saying this, however, our results do suggest that in this group, there appeared to be no adverse effects overall with using a more prescriptive approach to weight loss.

Conclusion Three years after a 12 week food based structured weight loss program monitored by dietitians, 87% of participants reported either a net weight loss or remaining weight stable, and 44% of participants reported maintaining a clinically important weight loss of ≥5%. We conclude that this was associated with long-term weight loss maintenance. Weight history, eating patterns, physical activity habits and psychological effects on wellbeing did not differentiate WLMs from WLRs, and therefore were not associated with long-term weight loss maintenance. To maximise success in long-term weight loss maintenance it may be important to incorporate preparation for adverse life events in future structured dieting programs.

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Acknowledgements

Manny Noakes and Jennifer Keogh for their ongoing support and direction. Funding for this study was provided by CSIRO Human Nutrition.

Acknowledgements are extended to the CSIRO for supporting this study. Many thanks to Julia Weaver for assistance in contacting participants, Julie Syrette for assistance in data analysis and Dr. Grant Brinkworth for assistance with physical activity variables. Extended thanks to Associate Professor

Appendix A. Study questionnaire

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