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Long-term efficacy of a behavior modification weight loss program: A comparison of two follow-up maintenance strategies
BEHAVIOR THERAPY 10, 8-13 (1979)
Long-Term Efficacy of a Behavior Modification Weight Loss Program" A Comparison of Two Follow-up Maintenance Strategies WILLIAM M. BENEKE AND BARBARA K. PAULSEN Lincoln University
Eight extension home economists, trained in the use of a behavioral weight loss program which emphasized stimulus control, treated a total of 148 overweight women in groups of about 10 subjects each. One hundred eleven subjects completed 20 weeks of treatment, losing a mean of 7.85 kg. These subjects were then assigned to one of two posttreatment maintenance conditions differing in the amount and fading of group contact over an 18-month follow-up period. There were no differences in weight maintenance between follow-up strategies. Significant differences among therapists were found for overall weight loss and for loss of subjects from treatment groups.
While behavioral weight loss programs have achieved substantial, sometimes spectacular, treatment success, there is a lack of research demonstrating the long-term efficacy of behavioral programs for obesity (Franks & Wilson, 1976; Brightweli & Sloan, 1977). Weight losses which are not maintained pose health risks which may exceed those of remaining overweight (Gordon & Kannel, 1973) and cannot justify the expenditure of often substantial professional resources. O'Leary and Wilson (1975) have suggested the use of "booster sessions" during the follow-up period to promote posttreatment weight mainResearch paper No. 51-9: 212,219, Human Nutrition Research Program, Department of Agriculture, Natural Resources and Home Economics, Lincoln University, Jefferson City, MO 65101. Portions of this paper were presented at the annual meeting of the Rocky Mountain Psychological Association, Albuquerque, New Mexico, May 1977. Study supported by USDA-CSRS Grants No. 416-15-05 and 516-15-23 awarded to Lincoln University, Jefferson City, MO 65101. Authors wish to acknowledge Mary Bess Kohrs, Lincoln University, and William T. McReynolds and Ruth N. Lutz, University of Missouri, for their assistance in the design and implementation of this study. Address reprint requests to William M. Beneke, Department of Education and Psychology, Lincoln University, Jefferson City, MO 65101. 8
0005-7894/79/010008-06501.00/0 Copyright ~ 1979 by Association for Advancement of Behavior Therapy All rights of reproduction in any form reserved.
BOOSTER SESSIONS IN WEIGHT CONTROL
9
tenance. Two experimental studies evaluating booster sessions have already been conducted. The first, Kingsley and Wilson (1977), found that booster sessions were superior to no-booster conditions at 3 and 6 months posttreatment but not at 9 and 12 months. However, booster effects were not significant in their group behavioral treatment condition. The second study, Ashby and Wilson (1977), failed to find significant effects of either frequency or content of booster sessions over a 12-month follow-up period. Research in our laboratory (McReynolds, Lutz, Paulsen, & Kohrs, 1976) found no differences at the end of treatment between a treatment which emphasized stimulus control and a multiple-technique treatment based on Wollersheim's (1970) focal group. During an 18-month followup, however, the stimulus control subjects achieved superior results, suggesting that a stimulus control approach, by producing durable environmental changes (e.g., rearranging cupboards, use of non-see-through storage containers) has potential long-term advantages for weight maintenance (Beneke, Paulsen, McReynolds, Lutz, & Kohrs, 1978). The present study combined a stimulus control treatment based on our previous work with booster sessions, evaluating the long-term efficacy of two posttreatment maintenance strategies: the gradual withdrawal of therapist contact during follow-up and continued treatment where posttreatment therapist contact is not faded out. In addition, this study explores the possibility of expanding the availability of behavioral treatment programs by using indigenous home economists as therapists. METHOD
Therapists. Eight extension area home economists (five with nutrition backgrounds and three with child development backgrounds) were given 3 days of training by a team consisting of three nutritionists and a behavioral psychologist. Only one of the home economists had previous exposure to behavior modification, that being limited to a single college course. Each home economist then recruited subjects in her own region and served as therapist for one to three groups of about 10 subjects each. A research nutritionist, who served as a therapist in our previous work, conducted a single treatment group for comparison purposes. Subjects. One hundred forty-eight women, 25 to 50 years of age and 20 to 60% overweight were recruited through newspaper advertisements. None took medication or had health problems which could influence weight change. At the beginning of treatment subjects averaged 37.5 years of age (o- = 8.0) and 81.9 kg of weight (tr = 10.1) and were an average of 40.4% overweight (o- = 14.6). 1 Relative to Metropolitan Life Insurance Co., New York. New weight standards for men and women. Statistical Bulletin 40:3 Nov.-Dec., 1959. This table was modified so that one desirable weight for each height category was calculated from the table by taking an average of the high and low weight listed for the medium frame. The heights are modified to account for the lack of shoes.
10
BENEKE AND PAULSEN
Treatment. Sixteen I-hr treatment sessions were spaced over 20 weeks. Treatment, emphasizing stimulus control and nutrition education, was similar to that of the " f o o d management" condition described in McReynolds et al. (1976). 2 Tape recordings of each treatment session were reviewed by the researchers, and weekly feedback to the therapists was provided by telephone. Follow-up. At the end of treatment, subjects who completed treatment were assigned by intact therapy groups to one of two maintenance conditions for an 18-month follow-up period. Subjects in both Continuous Treatment (CT) and Gradual Withdrawal (GW) conditions received monthly telephone calls from their leader for the first 2 months posttreatment and met as a group at the end of the third month. The CT subjects continued to meet monthly through 12-months posttreatment while the GW subjects met only at the end of the sixth and twelfth month posttreatment. Subjects in both conditions then met at the end of the eighteenth month posttreatment. The two maintenance conditions differed in the amount and spacing of the formal contact which was provided during the first 12 months of follow-up. The CT condition had more formal contact (10 meetings versus three for the GW condition) and an abrupt transition from monthly contact to no contact while the GW condition consisted of a gradual fading of group contact.
RESULTS Attrition One hundred eleven subjects completed the 20 week treatment period. Thirty-seven subjects were lost to the study during treatment for a variety of reasons. Analysis of follow-up attrition indicated that the CT and GW conditions were equivalent in attrition rates and in reasons for leaving the program. Subjects dropping during the follow-up period displayed treatment losses ranging from 2.4 SDs below the mean loss for all subjects to 1.9 SDs better than the mean. Of these 43 subjects, 27 fell within +_ 1 SD of the mean loss, and 41 fell within _ 2 SD. There were significant attrition differences among therapists [X" (16) = 41.01, p < .0006]. Four of the eight extension home economists had lost more than 5(~o of their subjects by the end of the follow-up period. The three home economists with child development backgrounds lost seven subjects (13%) during treatment and nine (17%) during the follow-up while home economists with foods and nutrition training lost 30 subjects (32%) during treatment and 34 (36%) during follow-up. These differences in attrition rates were also highly significant [X" (2) = 18.97, p < .0001]. Except for addition of self-reinforcement and self-punishment and minor class rearrangement, the treatment is identical to the food managementtreatment. A complete manual is availableupon request fromJSAS Catalog of Selected Documents in Psychology. Request JSAS document: MS 1023, Treatment Manual for the "Food Management" (Stimulus Control) Treatment ($6.00).
B O O S T E R SESSIONS IN W E I G H T C O N T R O L
11
Weight Loss Weight loss from the beginning of treatment was computed at the end of treatment and at the 3-, 6-, 12-, and 18-month follow-up classes for subjects attending each of these classes. Weight changes over time were significant IF (5,323) = 158.95, p < .0001]. Neither the effect of the maintenance conditions nor its interaction with time approached significance. The one hundred eleven subjects completing treatment lost a mean of 7.84 kg? The 58 CT subjects lost a mean of 7.86 kg while 53 GW subjects had lost a mean of 7.82 kg. Combining the two maintenance conditions, weight losses at 3-, 6-, 12-, and 18-months posttreatment were 9.19 (n = 82), 8.60 (n = 64), 7.76 (n = 71), and 6.24 kg (n = 68), respectively. Planned comparisons indicated that losses at the end of treatment and all follow-up points were significantly different from the beginning of treatment (0) and that the loss at 18 months was less than at 3 and 6 months (p < .01). ANOVA also yielded a significant therapist effect [F (9,133) = 8.73, p < .001]. Weight loss by therapists are plotted in Fig. 1. The four therapists whose total attrition rates exceeded 50% (solid lines in Fig. 1) had poorer losses (2.2 kg smaller) during treatment and/or the entire program. Weight loss differences attributable to therapist educational background were nonsignificant at the end of treatment and at all follow-up points. Therapist 9, the research nutritionist included so that the present data could be compared to that of our previous work, had a moderate attrition rate, a treatment loss very close to the overall mean, and somewhat poorer than average follow-up weight maintenance. An additional comparison of the present study to the stimulus control (food management) group in McReynolds et al. (1976) and Beneke et al. (1978) indicates that the weight-loss results of the present study are nearly equivalent to those obtained using research nutritionists as therapists in our previous work.
DISCUSSION These results suggest that booster sessions are of dubious value for long-term weight loss/maintenance. The results reported here indicated that fading out of booster contact did not promote weight maintenance relative to continued booster sessions. Both booster session conditions posted results similar to those of the comparable FM condition in Beneke et al. (1978) which had no booster sessions. Ashby and Wilson (1977) have also reported no effect for either frequency or content of booster sessions. Though Kingsley and Wilson (1977) reported an overall booster effect, this effect was not significant in their group behavioral treatment condition. 3 Analysis was also performed using the reduction index (RI) proposed by Feinstein as the d e p e n d e n t measure. The m e a n treatment RI was 51.48 (SD = 25.7). Since results with RI as the d e p e n d e n t m e a s u r e were essentially similar to weight change, no additional RI data are reported here. Complete RI information as well as data for individual subjects are available upon request.
12
BENEKE AND PAULSEN
~'9
I ~til
/''~'r><'~l_
_.. 'oi
....
END OF 3 Mo, TREATMENT
6 Mo.
_.- .............
FOLLOW-UP
12 Mo.
18 Mo.
FIG. 1. Mean losses measured from the beginning of treatment (Class l) as a function of therapist. Solid lines depict therapists who had highest attrition rates, and broken lines represent those with lower attrition in their groups. Therapists 3, 5, and 7 had child development backgrounds; therapists I, 2, 4, 6, and 8 had foods and nutrition backgrounds. Therapist 9 is the research nutritionist included to permit comparisons of these data with our earlier work.
Treatment based on stimulus control may hold promise for long-term efficacy. Both Beneke et ai. (1978) and the present study report long-term maintenance that is among the best in the obesity literature (Brightwell & Sloan, 1977). The relatively long-lasting environmental changes incorporated in this treatment approach seem to produce durable, long-term behavioral effects. The influence of the relatively high rate of attrition (25% by the end of treatment and 54% by the end of the 18-month follow-up) on weight loss data is difficult to specify. Attrition could have produced a small bias increasing maintenance as 26 dropouts had lost less than the mean at their last recorded weight, while only 17 had weight losses exceeding the mean. Attrition can also be considered as an effect of therapeutic intervention. Thus, one could argue that the loss of 14 subjects during treatment and 21 subjects during follow-up for reasons of motivation reflects an inability of the program and/or therapist to maintain these subjects' commitment to weight control. The significant therapist effects on attrition would seem to place this effect more with the therapist than with the program alone. Therapists trained in home economics/child development had lower attrition rates (and equivalent mean weight losses) in their groups than did therapists with home economics/foods and nutrition backgrounds. Rea-
BOOSTER SESSIONS IN WEIGHT CONTROL
13
sons for this effect are unclear. Additional research is needed to identify therapist variables related to the success of behavioral programs (Jeffrey, 1976). Therapist differences notwithstanding, this study indicates that extension home economists, provided with appropriate training and consultation, can serve as therapists for application of a behavioral weight loss program. REFERENCES Ashby, W. A., & Wilson, G. T. Behavior therapy for obesity: Booster sessions and long-term maintenance of weight loss. Behaviour Research and Therapy, 1977, 15, 451-463. Beneke, W. M., Paulsen, B., McReynolds, W. T., Lutz, R. N., & Kohrs, M. B. Long-term results of two behavior modification weight loss programs using nutritionists as therapists. Behavior Therapy, 1978, 9, 501-507. Brightwell, D. R., & Sloan, C. L. Long-term results of behavior therapy for obesity. Behavior Therapy, 1977, 8, 898-905. Franks, C. M., & Wilson, G. T. (Eds.). Annual review of behavior therapy: Theory and practice. New York: Brunner/Mazel, 1976. Vol. 4. Gordon, T., & Kannel, W. B. The effects of overweight on cardiovascular disease. Geriatrics, 1973, 28, 80-88. Jeffrey, D. B. Treatment outcome issues in obesity research. In B. J. Williams, S. Martin, & J. P. Foreyt (Eds.). Obesity: Behavioral approaches to dietary management. New York: Brunner/Mazel, 1976. Kingsley, R. G., & Wilson, G. T. Behavior therapy for obesity: A comparative investigation of long-term efficacy. Journal of Consulting and Clinical Psychology, 1977, 45, 288298. McReynolds, W. T., Lutz, R. N., Paulsen, B. K., & Kohrs, M. B. Weight loss resulting from two behavior modification procedures with nutritionists as therapists. Behavior Therapy, 1976, 7, 283-291. O'Leary, K. D., and Wilson, G. T. Behavior therapy: Application and outcome. Englewood Cliffs, NJ: Prentice-Hall, 1975. Wollersheim, J. P. Effectiveness of group therapy based upon learning principles in the treatment of overweight women. Journal of Abnormal Psychology, 1970, 76, 462-474. RECEIVED" March 10, 1978; REVISED"July 27, 1978 FINAL ACCEPTANCE"August 23, 1978
Long-Term Efficacy of a Behavior Modification Weight Loss Program" A Comparison of Two Follow-up Maintenance Strategies WILLIAM M. BENEKE AND BARBARA K. PAULSEN Lincoln University
Eight extension home economists, trained in the use of a behavioral weight loss program which emphasized stimulus control, treated a total of 148 overweight women in groups of about 10 subjects each. One hundred eleven subjects completed 20 weeks of treatment, losing a mean of 7.85 kg. These subjects were then assigned to one of two posttreatment maintenance conditions differing in the amount and fading of group contact over an 18-month follow-up period. There were no differences in weight maintenance between follow-up strategies. Significant differences among therapists were found for overall weight loss and for loss of subjects from treatment groups.
While behavioral weight loss programs have achieved substantial, sometimes spectacular, treatment success, there is a lack of research demonstrating the long-term efficacy of behavioral programs for obesity (Franks & Wilson, 1976; Brightweli & Sloan, 1977). Weight losses which are not maintained pose health risks which may exceed those of remaining overweight (Gordon & Kannel, 1973) and cannot justify the expenditure of often substantial professional resources. O'Leary and Wilson (1975) have suggested the use of "booster sessions" during the follow-up period to promote posttreatment weight mainResearch paper No. 51-9: 212,219, Human Nutrition Research Program, Department of Agriculture, Natural Resources and Home Economics, Lincoln University, Jefferson City, MO 65101. Portions of this paper were presented at the annual meeting of the Rocky Mountain Psychological Association, Albuquerque, New Mexico, May 1977. Study supported by USDA-CSRS Grants No. 416-15-05 and 516-15-23 awarded to Lincoln University, Jefferson City, MO 65101. Authors wish to acknowledge Mary Bess Kohrs, Lincoln University, and William T. McReynolds and Ruth N. Lutz, University of Missouri, for their assistance in the design and implementation of this study. Address reprint requests to William M. Beneke, Department of Education and Psychology, Lincoln University, Jefferson City, MO 65101. 8
0005-7894/79/010008-06501.00/0 Copyright ~ 1979 by Association for Advancement of Behavior Therapy All rights of reproduction in any form reserved.
BOOSTER SESSIONS IN WEIGHT CONTROL
9
tenance. Two experimental studies evaluating booster sessions have already been conducted. The first, Kingsley and Wilson (1977), found that booster sessions were superior to no-booster conditions at 3 and 6 months posttreatment but not at 9 and 12 months. However, booster effects were not significant in their group behavioral treatment condition. The second study, Ashby and Wilson (1977), failed to find significant effects of either frequency or content of booster sessions over a 12-month follow-up period. Research in our laboratory (McReynolds, Lutz, Paulsen, & Kohrs, 1976) found no differences at the end of treatment between a treatment which emphasized stimulus control and a multiple-technique treatment based on Wollersheim's (1970) focal group. During an 18-month followup, however, the stimulus control subjects achieved superior results, suggesting that a stimulus control approach, by producing durable environmental changes (e.g., rearranging cupboards, use of non-see-through storage containers) has potential long-term advantages for weight maintenance (Beneke, Paulsen, McReynolds, Lutz, & Kohrs, 1978). The present study combined a stimulus control treatment based on our previous work with booster sessions, evaluating the long-term efficacy of two posttreatment maintenance strategies: the gradual withdrawal of therapist contact during follow-up and continued treatment where posttreatment therapist contact is not faded out. In addition, this study explores the possibility of expanding the availability of behavioral treatment programs by using indigenous home economists as therapists. METHOD
Therapists. Eight extension area home economists (five with nutrition backgrounds and three with child development backgrounds) were given 3 days of training by a team consisting of three nutritionists and a behavioral psychologist. Only one of the home economists had previous exposure to behavior modification, that being limited to a single college course. Each home economist then recruited subjects in her own region and served as therapist for one to three groups of about 10 subjects each. A research nutritionist, who served as a therapist in our previous work, conducted a single treatment group for comparison purposes. Subjects. One hundred forty-eight women, 25 to 50 years of age and 20 to 60% overweight were recruited through newspaper advertisements. None took medication or had health problems which could influence weight change. At the beginning of treatment subjects averaged 37.5 years of age (o- = 8.0) and 81.9 kg of weight (tr = 10.1) and were an average of 40.4% overweight (o- = 14.6). 1 Relative to Metropolitan Life Insurance Co., New York. New weight standards for men and women. Statistical Bulletin 40:3 Nov.-Dec., 1959. This table was modified so that one desirable weight for each height category was calculated from the table by taking an average of the high and low weight listed for the medium frame. The heights are modified to account for the lack of shoes.
10
BENEKE AND PAULSEN
Treatment. Sixteen I-hr treatment sessions were spaced over 20 weeks. Treatment, emphasizing stimulus control and nutrition education, was similar to that of the " f o o d management" condition described in McReynolds et al. (1976). 2 Tape recordings of each treatment session were reviewed by the researchers, and weekly feedback to the therapists was provided by telephone. Follow-up. At the end of treatment, subjects who completed treatment were assigned by intact therapy groups to one of two maintenance conditions for an 18-month follow-up period. Subjects in both Continuous Treatment (CT) and Gradual Withdrawal (GW) conditions received monthly telephone calls from their leader for the first 2 months posttreatment and met as a group at the end of the third month. The CT subjects continued to meet monthly through 12-months posttreatment while the GW subjects met only at the end of the sixth and twelfth month posttreatment. Subjects in both conditions then met at the end of the eighteenth month posttreatment. The two maintenance conditions differed in the amount and spacing of the formal contact which was provided during the first 12 months of follow-up. The CT condition had more formal contact (10 meetings versus three for the GW condition) and an abrupt transition from monthly contact to no contact while the GW condition consisted of a gradual fading of group contact.
RESULTS Attrition One hundred eleven subjects completed the 20 week treatment period. Thirty-seven subjects were lost to the study during treatment for a variety of reasons. Analysis of follow-up attrition indicated that the CT and GW conditions were equivalent in attrition rates and in reasons for leaving the program. Subjects dropping during the follow-up period displayed treatment losses ranging from 2.4 SDs below the mean loss for all subjects to 1.9 SDs better than the mean. Of these 43 subjects, 27 fell within +_ 1 SD of the mean loss, and 41 fell within _ 2 SD. There were significant attrition differences among therapists [X" (16) = 41.01, p < .0006]. Four of the eight extension home economists had lost more than 5(~o of their subjects by the end of the follow-up period. The three home economists with child development backgrounds lost seven subjects (13%) during treatment and nine (17%) during the follow-up while home economists with foods and nutrition training lost 30 subjects (32%) during treatment and 34 (36%) during follow-up. These differences in attrition rates were also highly significant [X" (2) = 18.97, p < .0001]. Except for addition of self-reinforcement and self-punishment and minor class rearrangement, the treatment is identical to the food managementtreatment. A complete manual is availableupon request fromJSAS Catalog of Selected Documents in Psychology. Request JSAS document: MS 1023, Treatment Manual for the "Food Management" (Stimulus Control) Treatment ($6.00).
B O O S T E R SESSIONS IN W E I G H T C O N T R O L
11
Weight Loss Weight loss from the beginning of treatment was computed at the end of treatment and at the 3-, 6-, 12-, and 18-month follow-up classes for subjects attending each of these classes. Weight changes over time were significant IF (5,323) = 158.95, p < .0001]. Neither the effect of the maintenance conditions nor its interaction with time approached significance. The one hundred eleven subjects completing treatment lost a mean of 7.84 kg? The 58 CT subjects lost a mean of 7.86 kg while 53 GW subjects had lost a mean of 7.82 kg. Combining the two maintenance conditions, weight losses at 3-, 6-, 12-, and 18-months posttreatment were 9.19 (n = 82), 8.60 (n = 64), 7.76 (n = 71), and 6.24 kg (n = 68), respectively. Planned comparisons indicated that losses at the end of treatment and all follow-up points were significantly different from the beginning of treatment (0) and that the loss at 18 months was less than at 3 and 6 months (p < .01). ANOVA also yielded a significant therapist effect [F (9,133) = 8.73, p < .001]. Weight loss by therapists are plotted in Fig. 1. The four therapists whose total attrition rates exceeded 50% (solid lines in Fig. 1) had poorer losses (2.2 kg smaller) during treatment and/or the entire program. Weight loss differences attributable to therapist educational background were nonsignificant at the end of treatment and at all follow-up points. Therapist 9, the research nutritionist included so that the present data could be compared to that of our previous work, had a moderate attrition rate, a treatment loss very close to the overall mean, and somewhat poorer than average follow-up weight maintenance. An additional comparison of the present study to the stimulus control (food management) group in McReynolds et al. (1976) and Beneke et al. (1978) indicates that the weight-loss results of the present study are nearly equivalent to those obtained using research nutritionists as therapists in our previous work.
DISCUSSION These results suggest that booster sessions are of dubious value for long-term weight loss/maintenance. The results reported here indicated that fading out of booster contact did not promote weight maintenance relative to continued booster sessions. Both booster session conditions posted results similar to those of the comparable FM condition in Beneke et al. (1978) which had no booster sessions. Ashby and Wilson (1977) have also reported no effect for either frequency or content of booster sessions. Though Kingsley and Wilson (1977) reported an overall booster effect, this effect was not significant in their group behavioral treatment condition. 3 Analysis was also performed using the reduction index (RI) proposed by Feinstein as the d e p e n d e n t measure. The m e a n treatment RI was 51.48 (SD = 25.7). Since results with RI as the d e p e n d e n t m e a s u r e were essentially similar to weight change, no additional RI data are reported here. Complete RI information as well as data for individual subjects are available upon request.
12
BENEKE AND PAULSEN
~'9
I ~til
/''~'r><'~l_
_.. 'oi
....
END OF 3 Mo, TREATMENT
6 Mo.
_.- .............
FOLLOW-UP
12 Mo.
18 Mo.
FIG. 1. Mean losses measured from the beginning of treatment (Class l) as a function of therapist. Solid lines depict therapists who had highest attrition rates, and broken lines represent those with lower attrition in their groups. Therapists 3, 5, and 7 had child development backgrounds; therapists I, 2, 4, 6, and 8 had foods and nutrition backgrounds. Therapist 9 is the research nutritionist included to permit comparisons of these data with our earlier work.
Treatment based on stimulus control may hold promise for long-term efficacy. Both Beneke et ai. (1978) and the present study report long-term maintenance that is among the best in the obesity literature (Brightwell & Sloan, 1977). The relatively long-lasting environmental changes incorporated in this treatment approach seem to produce durable, long-term behavioral effects. The influence of the relatively high rate of attrition (25% by the end of treatment and 54% by the end of the 18-month follow-up) on weight loss data is difficult to specify. Attrition could have produced a small bias increasing maintenance as 26 dropouts had lost less than the mean at their last recorded weight, while only 17 had weight losses exceeding the mean. Attrition can also be considered as an effect of therapeutic intervention. Thus, one could argue that the loss of 14 subjects during treatment and 21 subjects during follow-up for reasons of motivation reflects an inability of the program and/or therapist to maintain these subjects' commitment to weight control. The significant therapist effects on attrition would seem to place this effect more with the therapist than with the program alone. Therapists trained in home economics/child development had lower attrition rates (and equivalent mean weight losses) in their groups than did therapists with home economics/foods and nutrition backgrounds. Rea-
BOOSTER SESSIONS IN WEIGHT CONTROL
13
sons for this effect are unclear. Additional research is needed to identify therapist variables related to the success of behavioral programs (Jeffrey, 1976). Therapist differences notwithstanding, this study indicates that extension home economists, provided with appropriate training and consultation, can serve as therapists for application of a behavioral weight loss program. REFERENCES Ashby, W. A., & Wilson, G. T. Behavior therapy for obesity: Booster sessions and long-term maintenance of weight loss. Behaviour Research and Therapy, 1977, 15, 451-463. Beneke, W. M., Paulsen, B., McReynolds, W. T., Lutz, R. N., & Kohrs, M. B. Long-term results of two behavior modification weight loss programs using nutritionists as therapists. Behavior Therapy, 1978, 9, 501-507. Brightwell, D. R., & Sloan, C. L. Long-term results of behavior therapy for obesity. Behavior Therapy, 1977, 8, 898-905. Franks, C. M., & Wilson, G. T. (Eds.). Annual review of behavior therapy: Theory and practice. New York: Brunner/Mazel, 1976. Vol. 4. Gordon, T., & Kannel, W. B. The effects of overweight on cardiovascular disease. Geriatrics, 1973, 28, 80-88. Jeffrey, D. B. Treatment outcome issues in obesity research. In B. J. Williams, S. Martin, & J. P. Foreyt (Eds.). Obesity: Behavioral approaches to dietary management. New York: Brunner/Mazel, 1976. Kingsley, R. G., & Wilson, G. T. Behavior therapy for obesity: A comparative investigation of long-term efficacy. Journal of Consulting and Clinical Psychology, 1977, 45, 288298. McReynolds, W. T., Lutz, R. N., Paulsen, B. K., & Kohrs, M. B. Weight loss resulting from two behavior modification procedures with nutritionists as therapists. Behavior Therapy, 1976, 7, 283-291. O'Leary, K. D., and Wilson, G. T. Behavior therapy: Application and outcome. Englewood Cliffs, NJ: Prentice-Hall, 1975. Wollersheim, J. P. Effectiveness of group therapy based upon learning principles in the treatment of overweight women. Journal of Abnormal Psychology, 1970, 76, 462-474. RECEIVED" March 10, 1978; REVISED"July 27, 1978 FINAL ACCEPTANCE"August 23, 1978