Cell Phone Intervention Alone May Not Lead to Sustained Weight Loss

Messaging, phone encounters boost primary care visits in diabetes
Messaging, phone encounters boost primary care visits in diabetes
Despite high engagement, a cell phone intervention did not increase weight loss.

Despite the benefits of mobile technology, effective weight loss interventions for young adults require social support and the human interaction of personal coaching in addition to a smartphone application, findings presented at ObesityWeek 2015 suggest.

These more personally tailored approaches may help obese patients to sustain weight loss, researchers reported.

“The study showed that a cell phone app that we designed based on behavior change principles and practice was not sufficient to promote weight loss over 2 years. A personal coaching intervention led to weight loss at 6 months, but not thereafter,” said study investigator Laura Svetkey MD MHS, who is a professor of medicine/nephrology at Duke University Medical Center in Durham, North Carolina.

Dr Svetkey, who presented the findings at the meeting, and colleagues looked at the effects of 2 mobile technology-based behavioral weight loss interventions in young adults aged 18 to 35 years. They conducted a randomized, controlled comparative effectiveness trial in individuals with a BMI of at least 25.

In the Cell Phone Intervention for You (CITY) study, participants were randomly assigned to 24 months of intervention delivered via interactive smartphone application on a cell phone, personal coaching enhanced by smartphone self-monitoring, or control.

A total of 365 participants (mean baseline BMI, 35) were included in the study.

Final weight was measured in 86% of participants, according to Dr Svetkey.

Interestingly, the researchers found that participants in the personal coaching group lost significantly more weight than control participants at 6 months (net effect, –1.92 kg; P=.003), but not at 12 and 24 months.

The study also demonstrated that the cell phone intervention did not lead to weight loss, whereas personal coaching did not lead to sustained weight loss relative to control, despite high intervention engagement and the inclusion of behavioral principles. 

“The CITY study is the longest and largest comparative effectiveness trial of weight loss intervention using mobile technology in young adults,” Dr Svetkey told Endocrinology Advisor

“Although mobile technology holds great promise for delivering weight control intervention to young adults and others, the approach used in this study was not effective. Mobile interventions probably need to be more intensive, better tailored to individual needs, and their development may need a paradigm shift in how we think about both behavior change and obesity treatment.”

Dr Svetkey also noted that commercial apps intended to promote healthy lifestyle and weight loss are currently very popular. However, behavior change principles are generally missing in most commercial products. 

At present, there are no scientific studies to support the contention that phone apps can help with permanent weight loss, she added. 

Dr Svetkey explained that this current study has significant limitations, and the cell phone intervention may have been ineffective because it involved no human intervention contact. Additionally, the characteristics of the study population may have contributed to the lack of sustained effect.

Also, mean BMI was 35, and 25% of participants had class III obesity. It is possible that the outcomes may have been different in participants who did not have well-established obesity or severe obesity, the researchers pointed out. They noted, however, that severe obesity is not necessarily an obstacle to behavioral weight loss, and baseline BMI did not modify the intervention effect.

“More than 35% of young adults (aged 18 to 35 years) are overweight or obese. Overweight/obesity during young adulthood predicts cardiovascular/metabolic risk factors in later life. This is the time of adult life when weight gain is most rapid. Given the role of mobile technology in this age group, this is also a population in which scalable technology-based treatments may be most useful,” said Dr Svetkey.

She highlighted the need for further studies to determine whether increasing coaching contacts and mobile elements and combining personal coaching and cell phone interventions may lead to sustained weight loss in overweight and obese patients. 


  1. Svetkey L. Obesity Journal Symposium. Cell Phone Intervention for You (CITY): A Randomized Controlled Trial of Behavioral Weight Loss Intervention for Young Adults Using Mobile Technology. Presented at ObesityWeek; November 2-6, 2015; Los Angeles, CA.
  2. Svetkey LP, Batch BC, Lin P-H, et al. Cell phone intervention for you (CITY): A randomized, controlled trial of behavioral weight loss intervention for young adults using mobile technology. Obesity. 2015;23(11):2133-2141.