Lifestyle and exercise

Fitness trackers 'don't help you lose weight'

"Fitness trackers may not help weight loss," reports Sky News on a new trial which investigated whether using wearable technology helped people lose more weight compared to standard weight-loss programmes.

Researchers tracked 470 overweight or obese people aged 18 to 35, for 24 months. Everyone in the study was put on a low-calorie diet, given an exercise plan and invited to regular group counselling sessions.

After six months, half the group was given a wearable device to track activity and feed it into a computer programme that also allows people to record their diet.

The other half were simply told to continue the weight loss programme and monitor their exercise and diet by themselves.

The group using the Fit Core tracker lost an average of 3.5kg over two years, compared with an average 5.9kg in the self-monitored group.

The spread of obesity across the globe has been increasing rapidly in recent years and public health bodies continue to struggle with tackling the issue.

Along with the usual weight-loss diets, the use of wearable technologies promoting fitness, such as FitBit and Jawbone, is also on the rise.

The study authors say there are many possible explanations for their surprising finding but, as yet, no proof.

BBC News quotes lead researcher Dr John Jakicic saying: "People have a tendency to use gadgets like these for a while and then lose interest with time as the novelty wears off.

"And we did see a drop off in the usage data as the study went on."

Although the study's findings are interesting, it may be the case that the use of fitness trackers and other devices may be more effective for some people than others.

Until more conclusive research is available, the best advice for losing weight is to follow a calorie-controlled diet combined with regular exercise.

Where did the story come from?

The study was carried out by researchers from the University of Pittsburgh in the US. It was funded by a grant from the National Institutes of Health and the National Heart, Lung and Blood Institute.

Interestingly, the researchers were affiliated with Weight Watchers International.

The findings from the trial were published in the peer-reviewed medical journal JAMA. It is free to read online.

Generally, media coverage around this topic was accurate.

What kind of research was this?

This was a randomised controlled trial (RCT) which aimed to compare the effectiveness of a wearable technology weight loss intervention (fitness tracker) with standard weight loss strategies to see which would result in greater weight loss.

RCTs such as this are one of the best ways to investigate the effectiveness of public health interventions.

In such trials there is the possibility that the individuals' knowledge of being monitored by the wearable technology could influence their diet, activity and weight loss. This is known as being non-blinded to the intervention group, which can normally be a potential source of study bias. However, in this case it's probably just part of the way the intervention was intended to work.

What did the research involve?

The 24-month Innovative Approaches to Diet, Exercise and Activity (IDEA) randomised controlled trial at the University of Pittsburgh recruited 471 participants (aged 18-35) with a body mass index (BMI) between 25.0 and 40.0.

Participants were randomised to one of two treatment groups: a standard behavioural weight loss intervention and a weight loss intervention enhanced by using wearable technology.

For the first six months both groups received the same behavioural weight loss intervention and were instructed to self-monitor dietary intake and their physical activity in diaries. This information was given to the study staff who offered feedback.

At six months, the standard behavioural weight loss group started self-monitoring their diet and physical activity via an website designed for the trial. No feedback was given. At this time, the enhanced intervention group were given their wearable technology device which had access to education materials via a web-based interface (BodyMedia FIT Core). This monitored their diet and physical activity.

During months 7-24, both groups also received telephone counselling sessions, text message prompts and access to online study materials.

The main outcome of the study was to assess weight change at 24 months. Participants were also assessed at months 0, 6, 12 and 18, and received monetary compensation for completing each assessment. The researchers analysed the findings between both treatment groups.

What were the basic results?

Overall, there was significant weight change over time in both treatment groups. However, there was greater weight loss in the standard behavioural intervention group compared with the technology-enhanced intervention.

  • The average weight loss between baseline and 24 months in the standard behavioural intervention group was 5.9kg (95% confidence interval (CI): 5.0 to 6.8).
  • In the technology-enhanced intervention group, the average weight loss over the same time was 3.5kg (95% CI: 2.7 to 4.5).
  • The difference between the two groups was 2.4kg (95% CI: 1.0 to 3.7).

Additionally, there was a greater decrease in body fat (%) in the standard behavioural intervention group compared with the technology-enhanced intervention.

  • The average loss of body fat (%) between baseline and 24 months in the standard intervention was 3.5% (95% CI: -4.0 to –3.0).
  • The enhanced intervention group lost on average 2.4% body fat (95% CI: -3.0 to -1.9).
  • The difference between the two groups was -1.1% in body fat (95% CI: -1.9 to -0.3).

How did the researchers interpret the results?

Researchers concluded: "Among young adults with a BMI between 25 and less than 40, the addition of a wearable technology device to a standard behavioural intervention resulted in less weight loss over 24 months. Devices that monitor and provide feedback on physical activity may not offer an advantage over standard behavioural weight loss approaches."


This trial aimed to compare the effectiveness of a wearable technology weight loss intervention (fitness tracker) with standard weight loss strategies to see which would result in greater weight loss at the end of 24 months.

It found the addition of a wearable technology device did not aid weight loss, and participants in the standard behavioural intervention group lost more weight when compared to the technology group.

This was an interesting study with a reliable study design. However there are a few things to note:

  • As the authors mention, the participants were all young adults (mean age 30) and 77.2% were women so these findings are not representative of the general population.
  • Although this trial showed weight loss over a 24 month period, the greatest weight loss was achieved in the first six months and this was not fully sustained over the long-term. Therefore, the challenges of maintaining weight loss continue to exist.
  • The adoption of the wearable technology device was started six months into the intervention so the findings may have been different had the participants started using them at baseline.

NHS Attribution