There are countless smartphone health trackers to help you count calories, but do these weight loss apps really work?

Millions of Americans track their daily caloric intake and fitness levels using smartphone apps. But according to new research, using these calorie-counting apps may not necessarily guarantee weight loss.

In the first of its kind, a study published in the Annals of Internal Medicine found that while health tracking apps may help those who want to lose weight, the apps do not produce results by themselves.

"This just shows us again that losing weight is really tough," said lead study author Dr. B. Yoshi Laing from the Martin Luther King Jr. Outpatient Center in Los Angeles. "Apps like this can be a powerful tool for people who are ready to track calories, but it's not for everybody to lose weight.

To test whether or not weight loss apps work, researchers introduced the app MyFitnessPal to overweight adults who   wanted to lose weight at two primary care centers in Los Angeles. 

Laing and colleagues recommended that some patients use MyFitnessPal, one of the most positively reviewed fitness apps with over 50 million users.

"I often think about how we only have 10 to 15 minutes with patients; what can we do to help them be healthy when they're not in front of me?,"Laing asked."I've been thinking about smartphone apps, but also the fact that there are thousands of these apps coming out every day, but we really don't know if they work."

Laing and colleagues asked half of the 212 study participants to use the app, which tracks calories and exercise and allows users to set goals and connect with others on social media. The other half were told about the study, but were told to use their own weight loss method. The name of the app was not disclosed.

After analyzing the patients' data for six months, Laing found that there was no significant difference in weight loss between those who used MyFitnessPal and those who did not.

But the study found a subgroup  of those who stuck with tracking their calories with MyFitnessPal were successful with their weight loss. In fact, the patient who used the app the most was the one to lose the most weight, 30 pounds.

"What we think happened is that the subset that used [the app] a lot, lost a lot of weight, but it seems like most people were really not ready to track calories; to commit that time to track calories," Laing said.

So while these apps may not guarantee weight loss, they still are a helpful tool. "Eighty-eight percent of people who log in for seven days will lose weight," Rebecca Silliman, a spokesperson for MyFitnessPal said. "The more you use it, the more weight you lose." 

Many patients began to stop using the app two months into their weight loss journey. Using weight loss apps is only a tool to make weight loss management easier, but it is not a quick fix. People have to commit to losing weight and increase healthier behaviors to see results. While the apps are effective, people have to be educated on healthy behaviors, on how to use to the app, and be consistent when using the app in order to really see healthy changes.

Just because a user logs food intake every day doesn't necessarily mean they will avoid eating unhealthy foods, but it does make a person more aware of their eating habits. Previous research has found journaling food intake is an effective method of weight loss.

Tracking your health on your smartphone is an easy way to take control of your health, just make sure you enforce healthy habits to make it effective.