Many weight loss studies are conducted by academic institutions, amongst people who live in cities – most commonly, people who are middle-class. New research published in Obesity sought to find out what would happen if, in a large-scale study, the weight loss intervention were provided to people who live in more remote areas. At the same time, the authors were curious to understand the effect of different dosages of weight loss counselling, both in terms of weight lost and cost of the intervention.
This study was a single blind, multi site, randomised controlled trial (in research terms, a gold-standard study) to evaluate the effect of three doses of behavioural lifestyle treatment on two-year changes in body weight for obese adults. The intervention was compared to a nutrition education program.
A total of 612 adults (aged between 21 to 75), with a BMI of between 30 and 45, participated in the study. Participants came from rural areas in northern Florida, in regions that were identified as “Health Profession Shortage Areas”.
Participants were divided into two broad groups: those who received the intervention, which was a lifestyle treatment involving weight loss counselling, or the control group, which involved a program of nutrition education.
Low, moderate and high dose lifestyle treatment
Amongst the lifestyle treatment group, participants received low, moderate or high doses of treatment. In phase one, this resulted in a set of 8 weekly group sessions for the low-dose intervention group, 16 weekly group sessions for the moderate dose group, and 24 weekly group sessions for the high dose intervention group.
In the second phase, those people receiving lifestyle treatment participated in a combination of scheduled telephone sessions (to reduce the travel burden for participants) and clusters of “campaign sessions” which were a set of weekly appointments working towards a shorter-term weight loss goal. The number of campaigns was reflective of the overall dose of treatment for each group, so the low-dose intervention group participated in one campaign, the moderate dose group saw two campaigns, and the high dose group participated in three campaigns during the course of the study.
Each group session included between 6 to 15 participants and the treatment included a low calorie eating pattern, increased physical activity and a focus on behaviour modification strategies such as goal setting, self-monitoring and problem solving.
Nutrition education (control group)
The control group participated in an 8-session series of lectures on nutrition, activity or weight control, followed by a group discussion on the topic. The schedule for the control group was identical to the contact schedule for participants in the low-dose lifestyle treatment group.
- Percent change in body weight between month 0 and month 24
- Percentage of participants in each group who achieved 5% or more weight lost by month 24
- The cost and cost effectiveness of each treatment (based on cost per kg lost per participant)
At six months, the proportion of participants who had lost more or equal to 5% of their starting body weight was 45%, 63%, 75% and 81% (for the control, low, moderate, and high-dose intervention groups respectively). At 24 months the proportion of participants who had lost more or equal to 5% of their starting body weight was 40%, 43%, 58% and 58% (again for the control, low, moderate and high-dose intervention groups). What is interesting to note is that the results are positive across all interventions; that between 6 and 24 months some participants re-gained the weight they initially lost (a common result for many weight loss studies), and that after 24 months the effect of the moderate and high-dose interventions yielded identical results with both groups showing 58% of participants maintaining 5% or more of their weight loss.
Based on these results, when costs per kg lost per patient were considered, the moderate dose intervention achieved the most cost-effective results. The total program cost per participant, per kilogram lost was $28 for the control group, $33 for the low-dose intervention group, $22 for the moderate-dose intervention and $25 for the high-dose intervention.
These results show that increasing treatment from 8 to 16 weekly sessions achieves both increased weight loss and improved cost efficiency. However, 24 sessions does not give sufficient increased weight losses to offset the increased cost of the extra treatment. It should also be noted that the control group achieved significant weight loss (but not as much as those participants receiving the lifestyle counselling intervention) – also showing the value of nutrition education to achieve weight loss.
A moderate dose of a community based, lifestyle intervention is an effective mechanism to achieve meaningful reductions in body weight. Additionally, a moderate dose of this type of intervention is lower cost than high-dose treatment but achieves very similar results after 24 months.
Perri, M. G., Limacher, M. C., von Castel-Roberts, K., Daniels, M. J., Durning, P. E., Janicke, D. M., … Martin, A. D. (2014). Comparative effectiveness of three doses of weight-loss counseling: Two-year findings from the rural LITE trial. Obesity, 22(11), 2293–2300.