Calorie-counters and workout trackers have become big business in mobile app stores. The weight loss industry is shifting quickly into the new mobile world. However, a new study is showing that these new weight loss apps may need improvement before they are effective at helping people stay slim.

The study, published in the American Journal of Preventive Medicine, shows that most weight loss apps do not implement many evidence-based strategies for changing eating and exercise behaviors. Researchers looked at 30 of the most popular weight loss apps currently available, looking for 20 “evidence-based behavioral strategies” found in the U.S. Centers for Disease Control’s Diabetes Prevention Plan. The strategies include things such as stress reduction, stimulus willpower control, and relapse prevention.

Of the 30 apps, 28 had five or fewer of these evidence-based weight loss strategies. The two that did have more of the strategies were found to implement only 13 of them.

“Apps do include evidence-based behavioral strategies, but only a narrow range,” said Sherry Pagoto, lead author of the study and a behavioral psychologist at the University of Massachusetts Medical School. “Strategies that often were missing are ones that help patients with adherence and motivation.”

While the overall impression of the apps is that they are lacking, the study found that there was no difference between free weight loss apps and paid weight loss apps. Free apps were found to contain as may evidence-based weight loss strategies as the paid ones. The top-rated apps, according to the study, are the paid and free versions of the MyNetDiary app.