Men need to lose weight just as much as women do. In fact, men in the U.S. are as likely to have BMIs in the obese range as women, and they are more likely to be obese in the United Kingdom. At the same time, men are less likely than women to participate in weight-loss programs. So more weight-loss interventions targeting men are needed.

A team of researchers in the UK recently ran a study with men they dubbed the Game of Stones, after a unit of measure for weight used there. It showed that adding financial incentives to text messages resulted in moderate but significant weight loss in men with obesity compared to a control group.

The study findings have interesting implications for obesity medicine. “In a field where studies of behavioral outcomes and non-cardiovascular outcome trials typically include majority female study populations, the researchers successfully engaged men,” the authors of an editorial related to the study point out.

Participants could keep the $490 USD if they met all their goals and they actually weighed in at family practice clinics.

Almost 40 percent of the participants lived in UK postal codes with lower socioeconomic status. Including them in decision making about the incentives and text messages may have contributed to the effectiveness of the text messages with financial incentives intervention, said the researchers.

Giving participants money to meet weight-loss goals, rather than using deposit contract incentives, which involve people depositing their own money and earning it back if they succeed at a particular behavior goal — similar to making a bet on oneself — may have encouraged men with lower incomes to enroll in the study, the researchers said.

A group of 585 men from three sites in the UK with a body mass index (BMI) of 30 or more participated in the clinical trial. They were randomly assigned to receive either one year of one behavior-focused text message per day plus financial incentives for meeting weight-loss goals or one year of daily text messages alone. A third control group was placed on a waiting list.

All participants received weight management information and a pedometer when they enrolled in the study.

The average weight loss was 5.7 kilograms for the text messages plus financial incentives group, 3.0 kilograms for the text messages alone group and 1.5 kilograms for the control group.

Men who received text messages and financial incentives had an average weight change of about five percent for the group from baseline to 12 months. For men who received text messaging alone, it was almost three percent for the group. The control group's weight change was one percent over the 12 months.

Compared to the control group, the difference in weight lost was significant for the text message plus financial incentives group but not for the text message-only group.

Fourteen percent of those in the financial incentives group received the full amount.

Those randomized to the financial incentives group were told that $490 USD had been placed in an account for them that they could access at the end of the study. But the money would be lost if their weight-loss goals were not met. These goals were five percent weight loss after three months ($64 USD guaranteed), 10 percent weight loss after six months ($191 USD) and maintaining 10 percent weight loss after 12 months ($254 USD).

Participants could keep the $490 USD if they met all their goals and they actually weighed in at family practice clinics. Additional money was earned for every additional one percent of weight lost between five percent and 10 percent at six and 12 months.

Fourteen percent of those in the financial incentives group received the full amount.

The researchers point out that the design of the study means that its findings may not be generalizable to women, diverse ethnic groups and those without mobile phones and that regaining weight is common after weight loss and could be greater for the financial incentives group. Follow-up information on the men's weight after 12 months is not yet available.

The United Kingdom study, a weight-loss study in the U.S. using a remotely delivered intervention and a related editorial about both are published in JAMA: Journal of the American Medical Association.