Wearing activity trackers motivates people to walk up to 40 minutes more each day and resulted in an average weight loss of 1kg (2.2 lbs) over five months, a study has found.
The research counters the scepticism regarding the effectiveness and accuracy of smart watches, such as Fitbits, and whether they fuel obsessive behaviours and eating disorders.
Researchers from the University of South Australia reviewed almost 400 studies involving 164,000 people across the world using wearable activity trackers (WATs) to monitor their physical activity. The findings appear to support a relatively low-cost solution to tackle health conditions caused by a lack of exercise.
"The overall results from the studies we reviewed shows that wearable activity trackers are effective across all age groups and for long periods of time," said lead researcher Ty Ferguson.
"They encourage people to exercise on a regular basis, to make it part of their routine and to set goals to lose weight."
The 1kg weight loss may not seem a lot, but researchers say from a public health perspective it is meaningful.
"Bearing in mind these were not weight loss studies, but lifestyle physical activity studies, so we wouldn't expect dramatic weight loss," said co-author Prof Carol Maher.
"The average person gains about 0.5kg a year in weight creep so losing 1kg over five months is significant."
Between 2014 and 2020, the number of wearable activity trackers shipped worldwide increased by an estimated 1,444%, with around £2.3 billion spent globally on them in 2020.
As well as weight loss, there is evidence fitness trackers help lower blood pressure and cholesterol and conditions partially caused by a lack of exercise including heart disease, stroke, type 2 diabetes and mental illness.
"The other reported benefit is that WATs improved depression and anxiety through an increase in physical activity," said Mr Ferguson.
Previous studies found that wearable activity trackers did little to improve fitness levels because users reverted to previous exercise levels after the novelty wore off - or stopped wearing them altogether.
They also argued that, because activity readings for fitness trackers can vary widely for the same amount of exercise, the data could not be taken seriously for any medical purposes.
Some users have spoken about how activity trackers made them unhealthily obsessive about their levels of exercise.
The report said: "Physical activity outcomes were consistently shown to improve in children, younger adults, adults, and older adults, with similar effect sizes. The beneficial effects for body composition were apparent across a range of populations, including healthy adults and those with obesity."