The Effect of Small Wins on Body Fat Loss

This study, which spans 24 weeks (12 treatment, 12 post-treatment), aims to compare the effectiveness of 2 financial incentive structures: smaller rewards for achieving intermediate goals vs. a large reward for achieving an overall goal - on weight loss. Male Singaporeans or Permanent Residents between the ages of 25 and 60 will be recruited. Participants must be healthy and have a body mass index (BMI) of between 23 and 27.5, and own and use a smartphone or tablet. Participants will be given an individual-tailored percentage body fat (PBF) goal and will be blinded from the presence of different treatment conditions and randomly assigned to one of the three conditions for 12 weeks:

1. Control group. Participants will receive only participation fees.
2. One large reward treatment. Participants will be awarded S$X for reaching the PBF goal at the end of 12 weeks.
3. Small wins treatment. Participants in the Small wins treatment condition will also be given 3 triweekly intermediate goals (IGs). Specifically, given the PBF goal, the PBF Loss Target (LT) is the difference between the initial PBF measured at the first visit and the goal, i.e., LT = initial PBF - PBF goal. Then, the IG1 is to achieve 25% of the LT, the IG2 is to achieve 50% of the LT, and the IG3 is to achieve 75% of the LT. The cash rewards that participants will receive are capped by S$X and depend on which IGs participants achieve and whether participants maintain their progress at the end of the 12 weeks.

All participants will be given an individual-tailored 12-week percentage body fat (PBF) goal. The formula for this goal will be set in consultation with medical and fitness professionals (including certified doctors and fitness trainers) to ensure that it is safe, challenging, and achievable. The base formula, which assumes a 5% weight loss as is often defined to be the medically significant level, is:

(P* W - x*5%*W)/(95%*W)

where P is PBF at baseline (week 1), W is body mass in kg at baseline, P*W is their body fat mass at baseline, and x, ranging between 0% and 100%, is the parameter that is set in consultation with professionals. At 100%, it implies that all 5% in weight loss is from fat, vice versa.

Because P and W differ between most persons, the formula tailors a different goal to each research subject. The formula is meant to be flexible toward each individual participant's baseline weight and body fat percent. Leveraging the 5% weight loss target, the investigators determined the expected percentage of this weight that is lost as fat, knowing that weight loss includes not only fat loss but also other components such as water loss. In previous studies, for 1 kg loss in weight, on average, 78.8% came from body fat. Hence, the investigators have targeted 80% of weight loss from the participants to come from body fat.

To examine changes in health, objective measurements will be made during scheduled participant visits on Weeks 1, 12, and 24. Measures include height, weight, waist circumference, and PBF. Each participant will also be given a free digital scale for personal use from home. Their weight and PBF data from the scale will be synchronized to a mobile application. The investigators will retrieve with the participant's consent to examine changes throughout the study's duration.

There are a total of 3 scheduled visits. The first in Week 1 allows baseline measures to be determined. During the first visit, the participants will be provided with a Weight Loss Brochure to warn against the harmful effects of excessive weight loss. The second visit in Week 12 marks the end of the treatment and allows treatment effects to be investigated. The last visit in Week 24 checks for post-treatment effects. During all 3 visits, the participants will also complete a Health Risk Assessment Survey. This survey should take no longer than 10 minutes to complete, and the research team will be physically present to assist the participants with it if so required.

Due to the uncertainty of the pandemic, the investigators may hold the second and/or the third research visits virtually (or at least provide an online option) to avoid large gatherings if necessary. For each virtual research visit, the research team will contact the participants through a video call, during which participants will step on the weighing scales and show the readings to the team. If a research visit is held online, the participation fee/rewards will be sent electronically. The research team will still hold physical meetings for those who experience technical difficulties.

To let the participants track their PBF progress, every participant would be given a digital scale for their keeping even after the research has concluded. Referring to the Health Products Act (HPA), this scale would not be defined as a "medical device." The digital scale serves simply, as would a conventional scale, to inform the user on some bodily metric. It does not attempt to make any medical judgment or recommendation for the user. The research team has done testing on the digital scale and is satisfied with the precision of the device. The participants are expected to weigh-in on the scales weekly from home at their convenience. In the middle of each of the 12 weeks (e.g., Wednesday or Thursday), an automated email will be sent to the participants reminding the participants to do so by the end of the week (Sunday). Non-compliance will not be penalized, but participants are strongly encouraged to weigh-in. The following is the complete list of data that the participants will access from the scale's mobile application. The researchers, with the participants' consent, will also retrieve this data for analysis: 1. Basal metabolism rate; 2. BMI; 3. Bone mass; 4. Metabolic age; 5. Muscle mass; 6. PBF; 7. Skeletal muscle weight ratio; 8. Subcutaneous fat; 9. Total body water; 10. Visceral fat; 11. Weight