Activity Monitors Provide No Improvement in Fitness Study

A two-year-long randomized trial has found that wearable monitors that track activity and vital signs — which are obviously designed to help people achieve their fitness goals — actually hindered weight-loss efforts in young adults with body mass indexes (BMIs) between 25 and 40.

The trial is among the first to test the long-term impact of such devices, which have become popular enough to inspire some hope that they might reverse the steady rise of both obesity and type 2 diabetes.

Investigators assigned 471 participants aged 18 to 35 years old to a standard program of diet and exercise, randomizing whether or not they’d be accompanied by technology designed to help track their activity and motivate them to achieve daily exercise goals.

Members of the standard intervention group no technology) began the trial with the mean weight of 95.2 kg (just under 210 lbs) (95% confidence interval [CI], 93.0 kg to 97.3 kg) and ended it with a mean weigh 89.3 kg (just under 197 lbs) (95% CI, 87.1 kg to 91.5 kg). Members of the enhanced intervention program began the study with a mean weight of 96.3 kg (about 212 lbs) (95% CI, 94.2 kg to 98.5 kg) and ended it with a mean weight of 92.8 kg (about 205 lbs) (95% CI, 90.6 kg to 95.0 kg).

The members of both groups had significant improvements in body composition, fitness, physical activity levels, and diet. The members of both groups also lost a significant amount of weight. However, the members of the standard intervention group lost significantly more than the members of the “enhanced” intervention group (5.9 kg [95% CI, 5.0 kg - 6.8 kg] vs. 3.5 kg [95% CI, 2.6 kg - 4.5kg]).

The results of the trial were hard to explain — not because it was inconceivable that technology would fail to inspire greater program adherence but because both groups adhered about equally to the weight loss program and yet lost significantly different amounts of weight.

Lesser weight loss for technology users “may be a result of the technology not being as effective for changing diet or physical activity behaviors compared with what was achieved with the standard intervention,” the study authors wrote in JAMA. “However, the study found no significant difference in these measures between the standard intervention and enhanced intervention groups. Thus, the reason for this difference in weight loss between the standard intervention and enhanced intervention groups warrants further investigation.”

Members of both groups received customized calorie prescriptions based upon their initial body weight. Dietary fat was prescribed at 20% to 30% of total calorie intake, and sample meal plans were provided to make it easier for participants to stick with the diet. Participants in the standard intervention group reported their food intake to investigators. Participants in the enhanced group self-monitored.

Members of both groups were also given exercise programs that began at 100 minutes of moderate-to-vigorous physical activity per week and increased at four-week intervals until they reached 300 minutes per week. Again, members of the standard group reported to investigators while members of the enhanced group self-monitored.

Both the standard intervention group and the enhanced intervention group received regular support: weekly group sessions for the first six months and then weekly text messages and monthly phone calls for the rest of the trial period.

Members of the enhanced group used a system from BodyMedia that combines a sensor worn around the wrist and software for tracking activity.

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