Using a smartphone app to monitor weight loss is effective if the user is willing to self-monitor calories, but for most patients, using a health app won't result in a substantial weight change, according to a UCLA study in the Annals of Internal Medicine of 212 primary care patients.

Researchers asked 105 participants to download the MyFitnessPal app, while the other 107 participants, the control group, did not receive any additional assistance. MyFitnessPal assisted in conducting the study, but the company did not fund the research.

"Most patients were simply not ready to commit the time to track calories. It takes several minutes to input everything you eat for each meal," study author Dr. Brian Yoshio Laing said in a statement. "Many patients felt it was too tedious, but some patients enjoy it and like getting the feedback on their daily caloric intake."

Notably, though the control group was blinded to the name of the app,  14 participants (13 percent) in the control group used MyFitnessPal as part of their weight loss regimen as well.

Six months after the trial began, the researchers looked at how much weight participants had lost, which was the primary outcome. The researchers also looked at several secondary outcomes including changes in participants' systolic blood pressure and behaviors, frequency of app use, and satisfaction.

Researchers found that there was no difference between the two groups when measuring weight loss and change in systolic blood pressure. The intervention group had an increased use of setting personal calorie goals, compared with the control group. The intervention group also reported high satisfaction with MyFitnessPal, although the researchers found that logins to the app decreased "sharply" after the first month of use.

"A faster, streamlined interface for entering foods may be a priority," Laing said. "Alternatively, weight-loss apps could assess an individual's readiness for self-monitoring before using the app and could prepare new users for the potential time commitment."

Researchers received funding from the Robert Wood Johnson Foundation Clinical Scholars Program, National Institutes of Health, and the Resource Centers for Minority Aging Research Center for Health Improvement of Minority Elderly under the National Institutes of Health for the study.