Cell-Phone App Doesn't Aid Weight Loss in Obese Youth

Marlene Busko

November 05, 2015

LOS ANGELES — In a randomized controlled trial of overweight and obese 18- to 35-year-olds, two behavior-modification strategies using cell phones did not lead to greater 2-year weight loss compared with "low-tech" written advice.

Specifically, the Cell Phone Interaction for You (CITY) trial randomized close to 400 youth to receive one of three weight-loss strategies: an intervention delivered by interactive smartphone application specifically designed by the research group ("cell-phone" intervention), personal coaching enhanced by smartphone self-monitoring ("personal-coaching" intervention), or simply a three-page handout (control) — all promoting healthy eating and more exercise.

Participants who received the personal-coaching intervention lost a mean of 1.92 kg more than controls at 6 months (P = .003), but not at 12 or 24 months, so the weight-loss effect was not sustained. And those who received the cell-phone intervention with the app (with built-in prompts) did not shed more weight than controls at any of these time points.

"CITY was the longest and largest trial [investigating the use of] cell phones" to try to modify eating and exercise behaviors, and the results "sound a cautionary note," about these weight-loss tools, said Dr Laura P Svetkey from Duke University Medical Center, Durham, North Carolina, presenting the findings at Obesity Week 2015.

The study was also simultaneously published in the November issue of Obesity.

"There is such an incredible rush to [adopt new] technology, with the thought that all these tools are really going to solve the [obesity] problem, but I think…we really need to step back and look at these things carefully before we all rush like lemmings toward them," session moderator and associate editor in chief of Obesity, Dr Donna H Ryan, from Pennington Biomedical Research Center, Baton Rouge, Louisiana, told Medscape Medical News.

Although not successful, this study provided important insights, she added. "It really emphasizes how much we can learn from negative studies."

"Should we be advising people to use commercially available weight-loss apps? I would say no," Dr Svetkey told Medscape Medical News. "A lot of them are free, but still you're investing time and energy, and it's taking you away from other approaches that may be more effective."

However, further research may identify subgroups that may benefit, she added. And perhaps CITY did not have a "sufficiently compelling or individually tailored app design."

Difference Between Cell-Phone and Coaching Arms

About one in three (35%) young adults in the United States is overweight or obese, and weight gain is most rapid at this age, Dr Svetkey explained. Despite this statistic, young adults have not been well-studied in weight-loss trials that adopt comprehensive behavioral approaches — they have primarily included middle-aged adults.

And although commercial mobile-health apps are widely downloaded for weight loss, they "have not been rigorously tested for efficacy or effectiveness," she and her colleagues explain in their paper. "Behavior-change techniques known to produce clinically meaningful weight loss are often absent, calling into question whether apps can have the desired effect."

The CITY study was one of seven trials in the Early Adult Reduction of Weight Through Lifestyle Intervention (EARLY) consortium, sponsored by the US National Heart, Lung, and Blood Institute (NHLBI).

Between 2010 and 2012, the researchers enrolled 365 18- to 35-year-olds who had a body mass index (BMI) >25 but weighed less than 440 pounds (200 kg; the limit of study scales) and used a mobile phone.

Individuals were excluded if they were taking weight-loss medications or corticosteroids, had had weight-loss surgery, or had any condition deemed unsafe for the study. Recruitment occurred primarily by advertising and mass mailings.

Participants were randomized to one of the three groups. The researchers hypothesized that weight change at 24 months (the primary outcome) and at 6 months and 12 months (secondary outcomes) would be better with the cell-phone and personal-coaching interventions.

The two interventions were designed to motivate participants to adopt the DASH healthy diet, do moderate physical activity at least 3 hours a week, limit their alcohol intake, and frequently monitor their weight, diet, and physical activity. Participants in these two study arms received an Android smartphone, reimbursement for their phone bill, and a Bluetooth-enabled scale.

Participants in the control group received three handouts on healthy eating and physical activity, from the Eat Smart Move More NC program but otherwise received no intervention and were not asked to self-monitor.

Weight Loss in Obese Young Adults

The major difference between the cell-phone and personal-coaching arms was the source of intervention delivery and the use of the smartphone.

In the cell-phone group, the smartphone was used for both intervention delivery and self-monitoring, through an investigator-designed app that included goal setting, challenge games, and social support through a "buddy system." Self-management behaviors were regularly and frequently prompted by the app according to a protocol-driven schedule; participants did not have a choice in the timing or frequency of prompts; tailoring occurred mainly via setting personal goals.

In contrast, the personal-coaching intervention was delivered primarily by an interventionist (a dietician) during six weekly group sessions followed by monthly phone contacts. Goal setting, challenges, and social support were delivered through these personal-coaching interactions, with extensive tailoring during the conversations with the interventionist. The smartphone was used exclusively for self-monitoring, with tracking of weight, dietary intake, and physical activity initiated by the participant (ie, without smartphone prompts), transmitted to the interventionist and incorporated by the interventionist into the coaching sessions.

At study entry, the participants had a mean age of 29.4 years, and 69.6% were women. The population was racially diverse (56.2% white, 36.2% black, 5.8% Hispanic). They had a mean BMI of 35.2 (range, 24.9 to 62.4). A quarter (29.9%) were overweight and another quarter were class 3 obese (BMI 40+).

Because commercial apps for weight loss were ubiquitous during the study, the researchers administered a retrospective questionnaire about app usage, which showed that many participants reported use of at least one commercially available app at least some time during the study (30% of the cell-phone group; 50% of the personal-coaching group; and 54% of the control group).

However, there was no evidence that the use of these commercial apps was associated with greater weight loss: the observed mean weight change from baseline to 24 months within the control group was -1.2 kg for users of such apps and -1.8 kg for nonusers, they note.

Great Heterogeneity in Weight Loss; Tailored Approach Needed

Retention was high: 86% of participants returned for a final weight measurement at 24 months.

Current guidelines define a 3% to 5% weight loss as clinically meaningful, and at 24 months 25.5%, 27.5%, and 22.0% of participants in the cell-phone, personal-coaching, and control groups, respectively, lost this amount of weight — which was not significantly different.

Although conclusions can be drawn only about the specific app tested, part of the lack of efficacy of the two interventions at 24 months might be due to the "surprising," better-than-expected weight loss in the control group, Dr Svetkey suggested.

The participants who enrolled in the trial were probably highly motivated to lose weight, she noted.

Overall, there was a great heterogeneity in response—from a loss of 41.3 kg to a gain of 31.8 kg, which suggests a need to develop more tailored interventions.

"Effective weight-loss intervention for young adults that can be implemented efficiently and broadly may require the scalability of mobile technology, the social support and human interaction of personal coaching, adaptive intervention design, and more personally tailored approaches," she and her colleagues conclude.

The CITY study was sponsored by a grant from the National Heart, Lung, and Blood Institute. Dr Svetkey is a consultant to Oregon Center for Applied Science, a health-innovation company that creates self-management programs to improve physical and emotional well-being. Disclosures for the coauthors are listed in the paper.

Obesity. 2015;23:2133-2141. Abstract


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