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The correlates of long term weight loss: a group comparison study of obesity

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The correlates of long term weight loss: a group comparison study of obesity
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  The correlates of long-term weight loss: a groupcomparison study of obesity J Ogden 1 * 1  Department of General Practice, Guys, Kings and St Thomas' Hospitals, Kings College, London, UK  OBJECTIVE: Although the majority of weight loss attempts are unsuccessful, a small minority succeed in both weightloss and maintenance. The present study aimed to explore the correlates of this success.METHOD: A group comparison design was used to examine differences between women who were classi®ed as eitherweight loss maintainers (had been obese (body mass index, BMI  30  kg a m 2 ) and had lost weight to be considerednon-obese (BMI ` 30kg a m 2 ) and maintained this weight loss for a minimum of 3y; n   44), stable obese (maintainedan obese weight (BMI  30  kg a m 2 ) for longer than 3y; n   58), and weight loss regainers (been obese(BMI  30  kg a m 2 ), lost suf®cient weight to be considered non-obese (BMI ` 30kg a m 2 ) and regained it(BMI  30  kg a m 2 ), n   40). In particular, the study examined differences in pro®le characteristics, historical factors,help-seeking behaviours and psychological factors.RESULTS: The results showed that in terms of pro®le and historical factors, the weight loss maintainers had beenlighter, were currently older and had dieted for longer than the other groups but were matched in terms of age, classand ethnic group. In terms of help-seeking behaviours, the weight loss maintainers reported having tried healthyeating more frequently but were comparable to the other subjects in terms of professionals contacted. Finally, forpsychological factors the weight loss maintainers reported less endorsement for medical causes of obesity, greaterendorsement for psychological consequences and indicated that they had been motivated to lose weight forpsychological reasons.CONCLUSIONS: Weight loss and maintenance is particularly correlated with a psychological model of obesity. Thishas implications for improving the effectiveness of interventions and the potential impact of current interest inmedical approaches to obesity. International Journal of Obesity  (2000) 24, 1018±1025 Keywords: obesity; successful weight loss maintenance; psychological models Introduction Obesity is generally de®ned as a body mass index(BMI,kg a m 2 ) of 30 or more. Using this de®nition,epidemiological studies in England reported that in1994 13% of men and 16% of women aged 16±64were obese and that the prevalence of obesity isincreasing. Comparable ®gures for 1980 were 6%and 8%, and by the year 2005 it is predicted that18% of men and 24% of women will be obese. 1 Because of its association with physical problemssuch as heart disease, cancer and diabetes 1,2 and itsmore controversial link with psychological problemssuch as depression and low self-esteem, 1,2  psycho-logists, nutritionists, dieticians and endocrinologistshave been involved in developing treatment pro-grammes for obesity. The traditional treatmentapproach focused on encouraging the obese to eat`normally' and this consistently involved putting themon a diet. 3 In contrast, recent comprehensive, multi-dimensional cognitive±behavioural packages aim to broaden the perspective for obesity treatment and combine traditional self-monitoring methods withinformation, exercise, cognitive restructuring, attitudechange and relapse prevention (eg Brownell 4 ). In1958, Stunkard concluded his review of the past 30yof attempts to promote weight loss in the obese withthe statement `Most obese persons will not stay intreatment for obesity. Of those who stay in treatment,most will not lose weight, and of those who do loseweight, most will regain it'. 5 In 1993, Waddenupdated this review and examined both the short-and long-term effectiveness of both moderate and severe caloric restriction on weight loss as determined  by randomized controlled trials (RCTs). 6 He exam-ined all the studies involving RCTs in four beha-vioural journals and compared his ®ndings to those of Stunkard. 5 Wadden concluded that `Investigators havemade signi®cant progress in inducing weight loss inthe 35y since Stunkard's review'. He states that 80%of patients will now stay in treatment for 20 weeksand that 50% will achieve a weight loss of 20lb or more. Therefore, modern methods of weight loss produce improved results in the short-term. However, *Correspondence: J Ogden, Reader in Health Psychology,Department of General Practice, Guys, Kings and St Thomas'Medical Schools, Kings College, 5 Lambeth Walk, LondonSE11 6SP, UK.E-mail: Jane.Ogden@kcl.ac.ukReceived 23 July 1999; revised 21 January 2000; accepted7 April 2000 International Journal of Obesity (2000) 24, 1018±1025 ß 2000 Macmillan Publishers Ltd All rights reserved 0307±0565/00 $15.00www.nature.com/ijo  Wadden also concludes that `most obese patientstreated in research trials still regain their lostweight'. This conclusion has been further supported  by a recent systematic review of interventions for thetreatment and prevention of obesity which identi®ed 92 studies which ®tted the authors' inclusion criteria. 7 The review examined the effectiveness of dietary,exercise, behavioural, pharmacological and surgicalinterventions for obesity and concluded that `themajority of the studies included in the presentreview demonstrate weight regain either during treat-ment or post intervention'. Accordingly, the picturefor long-term weight loss is almost as pessimistic as itever was.Therefore, RCTs examining the effectiveness of interventions indicate that, although the majority of individuals may lose weight initially, the large major-ity eventually return to their baseline weight. How-ever, within each trial a small minority not only loseweight initially but successfully maintain this loss.Research is therefore required to explore the differ-ences between the majority of individuals who either fail to lose weight, or regain any weight losses and theminority of individuals who are successful at bothweight loss and maintenance. What factors, therefore,may distinguish between the majority of failures and the minority of long-term successes? To date a fewstudies have speci®cally examined this minoritygroup. 8±13 This research together with data from theRCTs for obesity provide some preliminary insights.In particular, the literature highlights a role for a rangeof variables which, for the purpose of this study,have been conceptualized as pro®le characteristics,historical factors, help-seeking behaviours and  psychological factors.For pro®le characteristics, some studies suggest that baseline BMI 14±16 aspects of class, including employ-ment and income 15,17 and gender, 10,17 are important.However, the direction of such effects is not alwaysconsistent. For example, whilst some studies indicatethat lower baseline weight is predictive of greater weight losses and maintenance, 15 other studies indi-cate the reverse effect. 16 In addition, many of thesestudies only examine successful weight loss and maintenance in the short-term as the numbers of weight loss maintainers in the longer-term are small.Secondly, research highlights a role for historicalfactors including an individual's previous dietingattempts and their weight history. 11,12 In addition, itis possible that changes in their smoking behaviour  18 and their reproductive history may be contributoryfactors. 19 In terms of help-seeking behaviours, thereappear to be several variables which are predictive of success. Primarily, research highlights a role for the types and intensity of weight loss methodsused. For example, many studies emphasize theimportance of dietary changes such as caloriecontrolled diets, low-fat diets, high ®bre diets and healthy eating. 8,9,11,13,15,20,21 In addition, several stu-dies highlight the role of exercise and generalincreases in physical activity. 8,9,20,21 Furthermore,research has highlighted the relative effectiveness of different interventions involving contact with a rangeof health professionals. These include psychologicalinterventions such as cognitive±behavioural therapy(CBT), counselling, self-help groups and medicalinterventions involving drug therapy and surgery(see Ref. 7 for a review). The general conclusionfrom this research is that the more intense the inter-vention and the professional contact, the higher the probability of successful weight loss and maintenance.However, the relative impact of many of the differentforms of intervention remains unexplored.The ®nal area highlighted by the literature involves psychological factors. However, there is very littleresearch in this area. Rodin and colleagues 22 reported the results from a study designed to assess the baseline psychological predictors of successful weight loss.Their results indicated a role for the individual's beliefs about the causes of obesity and their motiva-tions for weight loss. A similar focus on motivationswas also reported by Williams et al  , 23 whose resultsindicated that motivational style was predictive of weight loss and maintenance. Likewise, Kiernan et al  12 indicated that individuals who were moredissatis®ed with their body shape at baseline weremore successful, suggesting that motivations for weight loss guided by a high value placed on attrac-tiveness may also be important. Research examiningother health problems such as chronic fatigue syn-drome suggest a possible role for other psychologicalfactors. In particular, research indicates a role for anindividual's model of their problem including their  beliefs about causes and consequences. 24 In summary, RCTs indicate that interventions for obesity are unsuccessful. However, a small minorityof individuals both lose weight and maintain thisweight loss in the longer-term. The present studyaimed to differentiate between the majority of indivi-duals who are unsuccessful and the minority of individuals who successfully lose and maintain their weight loss. In particular, the study aimed to examinedifferences between individuals who have been obeseand who have successfully lost weight and maintained this loss for at least 3y, obese individuals who havelost weight and regained it and individuals whohave remained obese for at least 3y, in terms of  pro®le characteristics, historical factors, help-seeking behaviours and psychological factors. Method Subjects All subjects were currently a member of a nationwideslimming club. A total of 80 questionnaires were sent by post to those individuals considered to be weightloss maintainers. In addition, 151 questionnaires weredistributed throughout the clubs as a means to access The correlates of long-term weight loss J Ogden 1019 International Journal of Obesity  the stable obese and weight loss regainers. Of these,51 of the postal questionnaires were returned giving aresponse rate of 63.7% and 111 of the hand-distrib-uted questionnaires were returned giving a responserate of 73.5%. Overall, this is a response rate of 70.1%. However, nine of the hand-distributed ques-tionnaires and seven of the postal questionnaires wererejected because the subjects did not ful®ll the criteriafor one of the three groups. In addition, four mencompleted the questionnaire and were excluded astheir number was insuf®cient to draw any meaningfulconclusions. Therefore, the ®nal response rate was61.5%. The responders were categorized into threegroups as follows: (i) stable obese ( n  58;BMI  30  for 3y or more); (ii) weight loss regainers( n  40; individuals who had been obese(BMI  30  ), lost weight in order to be non-obese(BMI ` 30) and regained weight in order to be cur-rently considered obese (BMI  30  ); (iii) weightloss maintainers ( n  44; individuals who had beenobese (BMI  30  ; lost weight in order to be con-sidered non-obese (BMI ` 30) and maintained thisweight loss for 3y or more). Design Because the target group (weight loss maintainers) issmall the study accessed this group directly. Thisenabled suf®cient numbers of individuals who had  been obese and had both lost and maintained weight to be compared to the control groups. Procedure The weight loss maintainers were recruited via thedatabase of a national slimming organization whokeep records of those members who have lost and maintained weight and have the heights and weightsof their current members, and were sent postal ques-tionnaires for completion. The remaining subjectswere recruited from individual slimming clubs inSouth East England and categorized into stableobese or weight loss regainers following questionnairecompletion. Measures All subjects completed questionnaires consisting of the following items. 1. Pro®le characteristics. Subjects recorded their age, sex, ethnic group (White a Asian a Black  a other),class (working a middle a upper), height and presentweight (to compute present BMI). In addition, sub- jects recorded their highest weight since 18y, lowestweight since 18y and completed a weight history for 2y intervals since they were 18y old. This was used tocompute their weight change history as a means tocategorize them into one of the three groups: stableobese, weight loss regainers, weight loss maintainers.Further, BMI difference scores were computed for thegaps between their highest ever and their present BMI,their lowest ever and their present BMI, their highestever and their target BMI (BMI  29), and their lowest ever and their target BMI (BMI  29). Inaddition, the length of time in years since they crossed the boundary for group categorization (BMI  29) wascomputed. For the stable obese this re¯ected thenumber of years since they became obese since theywere 18y (BMI b 29); for the weight regainers thisre¯ected the number of years since they regained their weight to be considered obese (BMI b 29) and for theweight loss maintainers this re¯ected the number of years since they could no longer be considered obese(BMI ` 30). 2. Historical factors. (i) Diet history: subjectsrecorded their current dieting status (yes a no), age of ®rst dieting attempt (y) and years of dieting (y). (ii) Clinical history: subjects recorded whether they had ever had the following: non-insulin-dependant dia- betes mellitus (NIDDM), insulin-dependant diabeticmellitus (IDDM), heart disease, angina, cancer, TB,overactive thyroid, underactive thyroid or joint trauma(Have now? yes a no; Had in past? yes a no). These weresummated to create a total number of health problemsscore. In addition, they recorded whether they had had any operations (yes a no). (iii) Health behaviours: smoking (Now? yes a no; ever? yes a no). (iv) Repro-duction: number of children; weight gain and main-tenance for ®rst child (lb). 3. Help seeking behaviours. (i) Weight loss methods :subjects rated the following weight loss methods for how often they had tried them ranging from `Never'(1) to `Very often' (5): calorie controlled diet, food avoidance, food weighing, low-fat diet, healthyeating, high ®bre diet, exercise, weighing yourself,surgery, counselling, cognitive behaviour therapy(CBT) (with a psychologist), self-help group, jawwiring. (ii) Professional contact: subjects rated thefollowing professionals for how much contact theyhad had with them ranging from `None' (1) to `Fre-quently' (5): practice nurse, GP, hospital doctor,dietician, counsellor, psychologist, slimming cluborganizer. 4. Psychological factors. Subjects rated a series of individual items relating to psychological factorswhich were summated to create total scores and examined for internal reliability using Cronbach'salpha as follows. (i) Beliefs about the causes of  obesity : subjects rated a series of items on a scaleranging from `strongly disagree' (1) to `stronglyagree' (5) to re¯ect the extent that they believed the following were causes of obesity which were The correlates of long-term weight loss J Ogden 1020 International Journal of Obesity  summated to provide total scores: (a) exercise (lack of exercise, not being physically active, inactive life-style; alpha  0.8); (b) diet  (eating fat, eating sweetfoods, eating high calorie foods, eating when nothungry; alpha  0.82); (c) medical  (genetics, hormoneimbalance, taking medication, eg HRT or the pill,slow metabolism, chemical imbalance in the brain;alpha  0.73); (d) psychological state (depression,lack of will power, laziness, lack of motivation;alpha  0.85). (ii) Beliefs about the consequence of  obesity: subjects rated a series of items to re¯ect theextent to which they believed they were consequencesof obesity which were summated to produce totalscores as follows: (a) medical  (joint problems, heartdisease, stomach cancer, bowel cancer, diabetes;alpha  0.87); (b) psychological  (depression, anxiety, phobias, low self-esteem, lack of con®dence;alpha  0.81). (iii) Motivations for weight loss: sub- jects rated a series of items on a scale ranging from`totally disagree' (1) to `totally agree' (5) to re¯ecttheir motivations for weight loss relating to thefollowing: (a) health (be healthier, live longer, be®tter; alpha  0.65); (b) attractiveness (be moreattractive, be able to wear nice clothes, feel morecon®dent about the way I look; alpha  0.59), (c) con®dence (increase my self-esteem, like myself more, feel better about myself; alpha  0.77); (c)  symptom relief   (feel less breathless, feel more ener-getic, feel more agile; alpha  0.8); (d) external pres- sure (please my family a  partner, please my friends, please my doctor; alpha  0.81). Results The results were analysed to examine differences between the three groups (stable obese, weight lossregainers, weight loss maintainers) in terms of their  pro®le characteristics, historical factors, help-seekingfactors and psychological factors using ANOVA and   post hoc tests for parametric data and Kruskal± Wallis a Mann±Whitney U  a Chi squared for non-para-metric data. Due to the number of comparisons beingmade, alpha was set at 0.01. 1. Pro®le characteristics Subjects' pro®le characteristics are shown in Table1. Overall, the results indicated that the stable obesehad been obese (BMI b 29) for 12.26y (s.d.  9.25),that the weight regainers had regained their weightin order to be reconsidered obese (BMI b 29) for 5.76y (s.d.  6.98) and the weight loss maintainershad been non-obese for 8.98y (s.d. 5.61). Further,the weight loss regainers had spent on average4.13y (s.d.  4.15) below the obese threshold (BMI ` 30). In terms of differences between thegroups, the results indicated that the three groupswere comparable in terms of their ethnic group,class and height. However, they were different interms of their age and present BMI. Post hoc testsindicated that the stable obese were younger than both the weight regainers and the weight lossmaintainers. In addition, the weight loss maintainersreported a lower present BMI than the other twogroups. In terms of changes in weight, the resultsindicated that the three groups were different intheir highest BMI ever, their lowest BMI ever and the gaps between their present BMI and their lowestever, highest ever and target BMIs. In particular,the weight loss maintainers reported a lower lowestBMI ever and a larger gap between their lowestBMI ever and their target BMI than both the stableobese and the weight loss regainers. Further, theweight loss maintainers reported a lower highestBMI ever, and a larger gap between this variableand their target BMI than the stable obese but werecomparable to the weight loss regainers on theselatter two variables. 2. Historical factors The subjects' diet, clinical, health behaviour and reproductive histories are shown in Table 2. Table 1 Pro®le characteristics Stable obese (n   58) Weight loss regainers (n   40) Weight loss maintainers (n   44) F  a w 2  a KW P  Age (y) a 38.39 Æ 12.79 45.57 Æ 11.30 43.95 Æ 9.44 F   5.48 P  ` 0.005  Ethnic group White  51 White  38 White  42 w 2  1.83 NSNon-white  4 Non-white  1 Non-white  1Class Working  33 Working  25 Working  20 w 2  4.85 NSMiddle  24 Middle  11 Middle  18Upper  0 Upper  1 Upper  0Height (m) 1.61 Æ 0.56 1.59 Æ 0.57 1.62 Æ 0.05 KW  3.29 NSPresent BMI a 37.96 Æ 5.55 33.79 Æ 3.40 24.77 Æ 1.96 KW  99.23 P  ` 0.0001 Highest BMI a 41.75 Æ 5.99 38.55 Æ 5.58 36.92 Æ 5.9 KW  20.92 P  ` 0.0001 Lowest BMI a 26.87 Æ 5.34 24.17 Æ 2.9 22.1 Æ 1.34 F   19.54 P  ` 0.0001 Now BMI-target a 7.89 Æ 5.52 3.67 Æ 3.38 7 5.29 Æ 1.92 F   130.87 P  ` 0.0001 High BMI-target a 11.67 Æ 5.95 8.43 Æ 5.50 6.85 Æ 5.94 F   9.15 P  ` 0.0001 Low BMI-target a 7 3.19 Æ 5.3 7 5.95 Æ 2.85 7 7.93 Æ 1.32 KW  35.11 P  ` 0.0001 a Signi®cant main effect of group. The correlates of long-term weight loss J Ogden 1021 International Journal of Obesity   Diet history. The results indicated that the groupswere comparable in terms of the age they ®rst started to diet. However, the weight loss maintainers wereless likely to be currently dieting, and reported havingtried to lose weight for longer than both the stableobese and the weight loss regainers. Clinical history. Subjects were comparable in termsof their number of health problems and whether theyhad had any operations.  Health behaviours. The three groups were compar-able in terms of their smoking behaviour (now a ever).  Reproductive history. The results indicate that thestable obese were less likely to have had children.However, of those that had had children, the threegroups had had comparable numbers of children.Further, the three groups were comparable in termsof weight gained and maintained for their ®rst child. 3. Help-seeking behaviours The subjects use of different weight loss methods and their professional contact are shown in Table 3.  Methods used. The results showed that the stableobese, weight loss regainers and weight loss main-tainers were comparable in their reported use of food avoidance, food weighing, self-weighing, low-fatdiets, high-®bre diets, exercise and self-help groups(no subjects had used surgery, counselling, cogni-tive±behavioural therapy or jaw wiring and thesewere removed from the analysis). However, theydiffered in terms of their reported use of caloriecontrolled diets and healthy eating. The results indi-cated that the weight loss maintainers reported greater use of healthy eating than both the stable obese and weight loss regainers. Further, the weight loss regai-ners reported more frequent use of calorie controlled diets than the stable obese.  Professional contact. The results showed that thethree groups were comparable in terms of their contactwith practice nurses, GPs, hospital doctors, dieticians Table 2 Historical factors Stable obese (n   58) Weight loss regainers (n   40) Weight loss maintainers (n   44) F  a KW  a w 2  P Diet history  Currently dieting a N  0; Y  61 N  0; Y  41 N  17; Y  25 w 2  45.15 P  ` 0.0001Age of ®rst diet (y) 21.25 Æ 10.26 22.55 Æ 10.18 18.83 Æ 7.89 F   1.64 NSYears of dieting a 14.96 Æ 10.52 19.58 Æ 10.87 22.48 Æ 9.82 F   6.42 P  ` 0.01 Health behaviour history  Smoker? N  48; Y  10 N  29; Y  11 N  30; Y  13 w 2  2.6 NSEver smoked N  29; Y  18 N  11; Y  18 N  21; Y  11 w 2  5.67 NS Clinical history  Health problems 1.26 Æ 1.25 1.55 Æ 1.50 1.06 Æ 0.94 KW  1.15 NSOperations N  19; Y  37 N  19; Y  19 N  13; Y  31 w 2  4.03 NS Reproductive history  Children a N  19; Y  38 N  6; Y  33 N  4; Y  40 w 2  9.82 P  ` 0.01No. of children 1.39 Æ 1.22 2.00 Æ 1.28 1.81 Æ 0.97 F   3.48 NSWeight gain for ®rst child (lb) 30.23 Æ 15.5 35.47 Æ 14.77 34.91 Æ 18.77 F   0.94 NSWeight maintenance for ®rst child (lb) 24.62 Æ 19.73 15.82 Æ 15.07 19.53 Æ 13.24 F   1.32 NS a Signi®cant main effect of group. Table 3 Help seeking behaviours: methods used and professional contact Stable obese (n   58) Weight loss regainers (n   40) Weight loss maintainers (n   44) F  a KW P Methods used  Calorie-controlled diet a 4.12 Æ 0.91 4.6 Æ 0.71 4.43 Æ 0.85 F   4.65 P  ` 0.01Food avoidance 2.55 Æ 1.42 2.58 Æ 1.37 2.59 Æ 1.17 F   0.01 NSFood weighing 3.49 Æ 1.38 3.91 Æ 1.27 4.25 Æ 0.93 KW  7.7 NSLow-fat diet 2.92 Æ 1.33 3.00 Æ 1.33 3.39 Æ 1.42 F   1.52 NSHealthy eating a 3.52 Æ 1.26 3.91 Æ 1.13 4.53 Æ 0.82 KW  18.82 P  ` 0.0001High-®bre 2.02 Æ 1.15 2.56 Æ 1.52 2.86 Æ 1.44 F   4.49 NSExercise 3.14 Æ 1.14 2.87 Æ 1.07 2.62 Æ 1.27 F   2.46 NSWeighing 3.28 Æ 1.28 3.53 Æ 1.15 3.93 Æ 1.16 F   3.52 NSSelf-help group 1.98 Æ 1.50 2.09 Æ 1.51 2.07 Æ 1.73 F   0.06 NS Professional contact  Practice nurse 1.47 Æ 0.82 1.67 Æ 1.07 1.26 Æ 0.63 F   2.24 NSGP 1.67 Æ 0.75 1.86 Æ 1.22 1.56 Æ 0.83 F   1.07 NSHospital doctor 1.11 Æ 0.39 1.06 Æ 0.35 1.12 Æ 0.45 F   0.25 NSDietician 1.44 Æ 0.69 1.29 Æ 0.57 1.24 Æ 0.58 F   1.44 NSSlimming club organizer 4.12 Æ 1.24 4.38 Æ 0.85 4.36 Æ 0.94 F   0.98 NS a Signi®cant main effect of group. The correlates of long-term weight loss J Ogden 1022 International Journal of Obesity
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