Objective: This investigation was designed to examine whether: (i) individuals could successfully lose 5% of their body weight with minimal assistance, (ii) weight loss would be improved by the addition of therapist assistance, and (iii) individuals unsuccessful at losing 5% total body weight during the minimal assistance phase (with or without therapist assistance) would benefit from a weekly weight loss group.
Methods and Procedures: Fifty-four overweight or obese adults (BMI > 27 kg/m2) initially participated in a 14-week self-help (SH) or therapist-assisted SH (TASH) weight loss program. Participants who were unsuccessful at losing 5% total body weight were stepped-up to a 3-month, group-based behavioral weight loss program (BWLP) with weekly weigh-ins.
Results: Although ∼60% of the participants were successful at losing 5% of their total body weight (lb) during the minimal assistance phase (M = 10.6; s.d. = 11.5; P < 0.01), treatment outcome was not improved by the addition of therapist assistance. For individuals who were unsuccessful at losing 5% of total body weight during a minimal assistance phase, the addition of a group-based BWLP did not improve their weight loss.
Discussion: While many individuals were quite successful at losing weight with minimal assistance, other individuals evidenced difficulties losing weight, even when participating in a greater intensity intervention (i.e., BWLP group).
In a stepped-care approach to weight loss, when a minimally intensive treatment (e.g., self-help (SH)) does not result in clinically meaningful weight loss, then a more intensive treatment (e.g., behavioral weight loss program (BWLP)) is implemented (1,2). Although minimally intensive weight loss programs have shown promise (3), weight loss outcomes are often modest (4). In addition, evidence for improved treatment outcomes with increased professional contact has been equivocal (3). In contrast, moderately intensive approaches (e.g., BWLPs) have been quite successful in promoting short-term weight loss (5).
In this investigation, participants were initially randomized to a minimally intensive SH or therapist-assisted SH (TASH) weight loss program (minimal assistance phase). Participants unable to achieve a 5% weight loss during the minimal assistance phase were stepped-up to a group-based BWLP (BWLP group phase). This investigation examined whether: (i) individuals could successfully lose 5% of their body weight with minimal assistance, (ii) weight loss was improved with therapist assistance, and (iii) individuals unsuccessful at losing 5% total body weight during the minimal assistance phase would lose significantly more weight during the BWLP group phase.
A total of 172 individuals inquired about taking part in a weight loss intervention that was advertised in local and regional newspapers. Of the 76 (44.2%) eligible participants, 54 (71.1%) chose to participate. Participants were included if they were (i) overweight/obese (BMI ≥ 27 kg/m2), (ii) nonsmokers; and excluded if they had (i) cardiovascular disease, (ii) musculoskeletal problems preventing moderate physical activity, or (iii) insulin dependent diabetes. All participants received their physician's medical clearance.
Participants' mean age was 46.2 (s.d. = 8.9; TASH: M = 45.6, s.d. = 8.8; SH: M = 46.7, s.d. = 9.4). Annual income exceeded $30,000 per year for ∼85% of the participants (TASH = 92%, SH = 78%, Not reported = 8) and 66% had at least a baccalaureate degree (TASH = 71%, SH = 61%, Not reported = 7). Most participants were white (94%; TASH = 96%, SH = 92%) and women (78%; TASH = 85%, SH = 71%). Mean baseline BMI (kg/m2) was 35.6 (s.d. = 7.3; range = 27.5–64.8; TASH: M = 34.6, s.d. = 8.7; SH: M = 36.5, s.d. = 5.7) and mean weight was 218.5 lb (s.d. = 52.9; range 147–426; TASH: M = 211.4, s.d. = 45.6; SH: M = 225.2, s.d. = 39.8).
Participants were randomly assigned to the SH (N = 28) or TASH (N = 26) condition. Forty-four participants completed the minimal assistance phase (SH: N = 21, stepped-up to BWLP = 10, No BWLP = 11; TASH: N = 23, stepped-up to BWLP = 9, No BWLP = 14). Thirty-nine participants remained following the BWLP group phase. The minimal assistance phase lasted 14 weeks and the BWLP group phase lasted 12 weeks. See Figure 1 for participant flow diagram.
During the minimal assistance phase, participants received a weight loss manual (6), an accelerometer to track energy expenditure, and instructions on how to self-monitor energy intake and physical activity. In addition, TASH participants received two 45-min face-to-face sessions as well as weekly 15–20 min telephone calls with a therapist. The first face-to-face meeting (week one of the program) utilized motivational enhancement principles (7) to sustain and improve weight loss motivation. The second face-to-face meeting (week seven) utilized problem-solving techniques (8) to solve participants' biggest eating or physical activity concern. Weekly telephone calls included a discussion of self-monitoring compliance, a goal check-in, a brief discussion of the assigned readings, and goal setting for the following week.
All participants received a 5% weight loss goal during the minimal assistance phase. If participants were unable to achieve a 5% weight loss during this phase, they were stepped-up to the weekly group-based BWLP (6). If participants were able to maintain a 5% weight loss for at least 6 weeks following the minimal assistance phase (6-week monitoring period), they began a weight maintenance intervention.
The weight loss manual used in the minimal assistance as well as the 3-month BWLP groups was the LEARN program (6). The BWLP group phase consisted of weekly, 75-min sessions, with nine or ten participants per group, led by a licensed clinical health psychologist or master's level clinical psychology doctoral students with experience in leading weight loss interventions. The LEARN program encourages gradual weight loss, progressively increasing physical activity, and decreasing energy and fat intake through permanent lifestyle changes. Through didactic instruction, individual activities, and weekly out-of-class assignments, the program emphasizes (i) self-monitoring, (ii) stimulus control, (iii) physical activity, (iv) nutrition education, (v) cognitive restructuring for negative thoughts associated with dieting and body image, (vi) goal setting, and (vii) relationships. Participants were encouraged to self-monitor energy intake, energy expenditure (i.e., using accelerometers), and physical activity throughout the program.
Body weight was measured using a digital scale to the closest 0.1 lb. Height was measured in inches to the closest 0.5 inch using a height rod on a standard spring scale.
No significant differences in baseline demographics between TASH and SH individuals or between program completers and dropouts (N = 15) emerged. TASH participants averaged 1.9 (s.d. = 0.3) face-to-face sessions and 8.8 (s.d. = 2.7) telephone calls during the minimal assistance phase. During the BWLP group phase, participants attended, on average, 5.9 (s.d. = 3.9; 49%) group sessions.
A 2 (SH; TASH) × 2 (baseline; post-minimal assistance phase) repeated-measures ANOVA indicated a significant overall treatment effect for weight (lb), F (1,42) = 36.3, P < 0.001, (M = 10.6; s.d. = 11.5; 5.2% of total body weight). The group by treatment interaction effect was not significant (TASH: M = 11.5, s.d. = 10.9; SH: M = 9.6, s.d. = 12.4). TASH participants were not significantly more likely to reach their 5% weight loss goal than SH participants. Twenty-five participants (56.8%) lost at least 5% total body weight during the minimal assistance phase (11 SH (52.4%); 14 TASH (60.9%)). Among TASH participants, greater therapist contact was positively associated with greater weight loss (r = 0.69, P < 0.001). Although mean and percent body weight loss were modestly diminished when intent to treat analyses were performed (baseline carried forward method), the findings remained unchanged (F(1,52) = 32.6, P < 0.001; see Table 1).
Table 1. Weight loss during minimal assistance phase
For individuals who participated in the BWLP group phase (i.e., <5% weight loss), a 1 × 3 (baseline, post-minimal assistance, post-BWLP group) repeated-measures ANOVA indicated no overall treatment effect for weight loss, F(1,13) = 0.01, P < 0.995 (see Figure 2). There was virtually no weight change from baseline through the end of the BWLP group (baseline: M = 207.2, s.d. = 29.1; post-minimal assistance: M = 207.3, s.d = 30.1, post-BWLP: M = 207.1, s.d. = 33.1). Number of BWLP sessions attended was not associated with weight loss.
For individuals who lost 5% body weight during the minimal assistance phase, a 1 × 3 (baseline, post-minimal assistance, post-monitoring period) repeated-measures ANOVA with paired-sample contrasts indicated a significant treatment effect for weight loss, F(1,23) = 89.4, P < 0.001 (see Figure 2). Although participants continued to lose weight during the 6-week monitoring period, only weight loss during the minimal assistance phase was significant (t(24) = 12.1, P < 0.001; baseline: M = 222.7, s.d. = 65.8; post-minimal assistance: M = 204.0, s.d. = 60.5, postmonitoring M = 203.4, s.d. = 61.5).
During the minimal assistance phase, participants lost, on average, 5.2% of their total body weight, and nearly 60% reached their 5% weight loss goal. However, weight loss was not improved with therapist assistance. In addition, individuals stepped-up to a BWLP group due to their inability to lose 5% body weight during the minimal assistance phase were remarkably unsuccessful at losing weight. During the 12-week BWLP group, participants lost, on average, 0.15 lb.
Concepts articulated in the Transtheoretical Model's stages of change may shed light on the findings from this investigation (9). It is plausible that individuals who are ready and motivated to lose weight, such as those individuals in the late preparation (i.e., ready to take action) or early action (i.e., beginning to make changes) stages of change, may necessitate only minimal assistance to successfully lose weight. Because they are sufficiently motivated, regular contact with a therapist or participation in a BWLP group might not be essential for successful weight loss. However, some individuals in an early stages of change might be aware that a weight problem exists and may even be seriously thinking about losing weight (e.g., contemplation stage), but these individuals have not yet committed themselves to taking action. For individuals without a clear commitment to action, even greater intensity treatment may still prove insufficient to produce weight loss. Alternatively, because treatment content (i.e., LEARN program) in the minimal assistance and BWLP group phases was similar, the BWLP groups may have been viewed as offering little new material to struggling weight loss participants. Also, other medical or behavioral complications, such as binge eating, may have adversely influenced treatment outcomes despite adequate participant motivation (1). Finally, the small sample in this investigation had limited power to detect group differences that did not evidence a large effect size. For example, a small effect size was evident when examining the weight loss difference between the TASH and SH condition (TASH: M = 11.5, s.d. = 10.9; SH: M = 9.6, s.d. = 12.4) during the minimal assistance phase.
Consistent with a stepped-care perspective, it is clear that some individuals can be quite successful at losing weight with a minimally intensive intervention. However, other individuals, who are not adequately engaged by program content, have not yet made a firm commitment to take action, or are experiencing psychological complications that are interfering with treatment, are unlikely to benefit from a greater intensity intervention. Designing specialized interventions that increase readiness for committed action as well as target behavioral complications and individual treatment preferences will be necessary for improving weight loss treatment outcomes and combating the obesity epidemic.