Text messages with financial rewards boost weight loss in obese men, study finds

By Dr. Priyom Bose, Ph.D.Reviewed by Benedette Cuffari, M.Sc.May 16 2024

A recent JAMA Network study investigates whether text messages with or without financial incentives promote weight loss in men with obesity.

Study: Text Messages With Financial Incentives for Men With Obesity: A Randomized Clinical Trial. Image Credit: nada_if / Shutterstock.com

Targeting obesity in men

In the United Kingdom, approximately 26% of adult men are considered obese. Several studies have demonstrated that obesity impacts mobility and increases the risk of type 2 diabetes, cancer, and heart disease.

Men are less likely than women to participate in weight loss programs; therefore, an effective strategy is needed to motivate this group to participate in weight reduction interventions.

A systematic meta-analysis of clinical trials revealed that text messaging-based weight loss interventions could lead to significant weight loss compared to controls. However, most of the clinical trials considered in this meta-analysis included a small cohort of men. 

About the study

Scientists hypothesized that a combination of behavior change methods with financial incentives could be an effective strategy to promote weight loss in obese men. The Game of Stones clinical trial was designed to determine whether the combinational intervention of text messaging with or without financial incentives could promote weight reduction in obese men at a 12-month follow-up visit. 

The current assessor-blind and superiority multicenter trial was conducted in three U.K. regions, including Belfast, Glasgow, and Bristol. Study participants were recruited between July 2021 and May 2022, whereas the final follow-up visit occurred in June 2023.

Eligible candidates were randomly assigned to one of the three groups designed based on three treatments. These treatments included text messaging with financial incentives, only text messaging, and a waiting list (control) for 12 months.

Adult men with body mass index (BMI) values of 30 or more were included in the study. Individuals in either of the intervention groups without any financial incentives received identical texts daily. These texts were mostly related to weight management evidence, self-determination theory, and behavior change techniques based on the Health Action Process Approach. Study participants received text messages within a week of their group allocation.

All study participants assigned to the financial incentives group were told that they would receive £400 at the end of the clinical trial. These participants were also informed that they would not receive the financial incentive if they failed to reach the weight loss goals.

Study participants with a 5% weight loss from baseline at three months and a 10% weight reduction from baseline at six months would receive a financial incentive of £50 and £150, respectively. Furthermore, study participants would receive an additional £200 if they were able to maintain a 10% weight loss at 12 months. 

Study findings

Behavioral text messages combined with financial incentives reduced body weight by 3.2% compared to the control group. Text messaging alone did not significantly impact weight reduction among obese men.

A total of 1,073 men were enrolled in the current study, 585 individuals met the eligbility criteria and were randomized into the three intervention groups. 196 participants were assigned to text messaging with the financial incentives group, 194 to text messaging alone group, and 195 to the control group.

Approximately 75%, 66%, and 78% of participants belonging to text messaging with financial incentives, text messaging alone, and control groups, respectively, completed the study. 

Although 5% weight loss is generally regarded as a clinically meaningful outcome, some studies have shown that weight reduction below 5% could also be clinically significant. Notably, financial incentives attracted obese men from lower-income groups and those from disadvantaged areas to participate and meet each weight reduction goal.

Study limitations

The study cohort was limited to men and did not consider diverse ethnic groups, women, people with low literacy, and those with poor vision, thus limiting the generalizability of the findings. Furthermore, people without a mobile phone were excluded.

The dropout rate among men assigned to the text messaging alone group was significantly greater than that of the other two groups. A follow-up beyond 12 months was also needed, as the possibility of weight gain after weight loss trials is a common occurrence.

Since the trial did not conduct a 2 × 2 factorial design, the authors failed to assess whether the weight loss was due to text messaging with financial incentives or only financial incentives in the study cohort.

Despite these limitations, the current study highlights that a combined intervention of text messages and financial incentives promoted more significant weight loss in obese men than in the control group.