4.b. Comparison of Behavior Therapy Strategies
Another way to examine the efficacy of behavior therapy in the treatment of overweight and obesity is to evaluate studies that compare various behavioral techniques with one another. Of 31 RCTs that compared one or more behavioral interventions, 19 were deemed acceptable.
Of the 19 RCTs, 17 produced weight loss (367, 476, 479-493). Behavioral strategies to reinforce changes in diet and physical activity in obese adults produce weight loss in the range of 10 percent of baseline over 4 months to 1 year. The greatest amount of weight loss was usually observed in less than 12 months of the intervention; however, weight loss was observed for up to 2½ years in some studies. Multimodal strategies worked best, and the intensity (number of contacts and duration) and degree (albeit difficult to discern in some of these studies) of a particular reinforcement were most related to weight loss. Although initial therapy proved successful, it also appeared that when behavioral therapy ceased, weight was regained on average, but not all subjects relapsed back to baseline levels. Ten of the 19 studies were based on at least 1-year results (367, 476, 479, 480, 484, 486-488, 492, 493).
Fourteen trials compared different behavior therapy strategies. Two trials compared cognitive behavior therapy techniques, specifically cognitive rehearsal, social pressure, and cue avoidance (see Glossary) with other behavior therapies (479, 480). With regard to weight loss, cognitive rehearsal was no more effective than the group support or social pressure condition and was less effective than cue avoidance (480). Another study indicated no clear benefits for cognitive rehearsal above and beyond other behavioral strategies (479). One (483) of two studies that assessed the effect of monetary incentives reported greater weight loss (367, 483).
The effect of extending treatment in various ways was evaluated in several studies (486, 487, 489, 494). One study evaluated 20 weeks versus 40 weeks of standard behavior therapy and found greater weight loss with the extended therapy that was maintained at 72 weeks (486). Another study evaluated behavior therapy and the effect of a post-treatment therapist on weight loss (487). The study evaluated the effect of extended treatment using therapist contact in general, therapist contact emphasizing social influence, and extended treatment emphasizing physical activity. The emphasis of physical activity plus social influence produced greater weight loss than not having contact emphasizing these components. Extended contact with a therapist produced about 10 kg (22 lb) greater weight loss than no extended contact, even over the long term. At 18 months, all strategies that combined behavior therapy with a post-treatment maintenance program yielded a significantly greater long-term weight loss than behavior therapy alone.
Another study examined the effect of extending cognitive behavior therapy for 3 months in addition to the initial 3 months of therapy for obese patients with binge eating disorder, and found that extended cognitive behavior therapy improved binge eating behavior, although not weight (494). A pilot study of women with type 2 diabetes compared a 16-week group-behavioral weight loss program to the same group, but with three individualized motivational interviewing sessions added. Both groups demonstrated significant weight loss with the motivational group losing 5.5 kg (12.1 lb) on average and the standard behavioral group losing 4.5 kg (9.9 lb); there were no differences between the two. However, those in the motivational interviewing group demonstrated better attendance at meetings (attending on average 13.3 meetings versus 8.9 meetings), had significantly better glucose control, and recorded blood glucose and food diaries more frequently (489) than did members of the standard behavioral group.
A study that involved self-instruction plus incentives versus group instruction plus incentives demonstrated no effect of the group treatment on weight loss (481). Weight loss was positively associated with attendance; however, mandatory attendance did not seem to increase program effectiveness and seemed to discourage attendance among men. The program was equally effective when implemented through either self-help materials or by professionals. Another study compared stimulus-narrowing during the reintroduction of food (achieved by providing prepackaged food) for those on VLCDs to providing regular food during the reintroduction (495). They also compared reintroduction of foods based on progress in losing weight or maintaining weight loss versus a time-dependent basis. Neither strategy was helpful in maximizing weight loss or weight maintenance.
Two trials evaluated the impact of spousal involvement versus no spousal involvement in behavior therapy (488, 492). One study found no overall differences in weight loss between those treated with spouses and those treated without spouses; however, women lost more weight when treated with a spouse, and men did better when treated alone (P < .01 at end of treatment; P < .06 at 1 year) (492). Another study found a positive effect of spousal involvement on weight loss soon after treatment was completed; however, this effect had largely dissipated by the 3-year follow-up (488).
In summary, a variety of behavioral therapy strategies promote weight loss, with no one particular behavioral strategy having the greatest efficacy. Multimodal strategies with greater intensity appear to be most effective.
Rationale: Studies have shown that while weight loss is achieved, it is very difficult to maintain over a long period of time (1 to 5 years) in the absence of continued intervention (436, 477, 486, 491). This emphasizes the great importance of continuing a maintenance program on a long-term basis.
Rationale: One RCT examined the impact of different levels of behavior therapy in combination with diet and aerobic exercise on cardiorespiratory fitness (484). Subjects were randomly assigned to one of three groups which varied in their degree of training in, and detailed application of, behavioral change principles (described as the basic, extended, and maximal behavioral therapy groups). All groups incorporated frequent intensive therapist contact, self-monitoring of behavior, regular objective assessment, and feedback of change in status. The three groups differed in the degree of emphasis given to behavioral self-management training, amount of detail provided on individual risk factors and overall coronary heart disease risk, and establishment of realistic short-term goals for coronary risk factor change. In terms of cardiorespiratory fitness, the group receiving the extended behavioral therapy and the group receiving the maximal behavior therapy showed improvements in VO2 max of 2.90 and 3.40 mL/kg/min, respectively, when compared with controls who received the basic behavior therapy. However, it is unlikely that behavior therapy caused these improvements independent of weight loss.
No RCT evidence exists on the effect of behavior therapy combined with diet and physical activity on changes in abdominal fat as measured by waist circumference.