This is a randomized trial comparing two different interventions for sustainable weight loss. Specifically researchers will compare a current best practice (CBP) intervention that includes standard dietary advice with a new Healthy Weight for Living (HWL) intervention that includes recommendations to eat a diet rich in protein, dietary fiber and low glycemic index carbohydrates. The population will be adult dependents of Active Duty (AD) military personnel or retired military personnel (direct intervention participants) and the AD or retired military personnel they live with (indirect intervention participants). The primary outcome will be weight change from baseline to 1 year in the adult dependents. The objective of this study is to compare the CBP and HWL interventions when delivered to adult dependents of AD or retired military personnel and measure weight loss effects in both the adult dependents and the AD or retired military personnel they live with. The working hypothesis is that that the HWL intervention will result in significantly greater weight loss over 1 year than the CBP intervention in an intent-to-treat analysis in adult dependents, and that the greater weight loss in HWL will be associated with greater management of hunger and greater adherence to the goal of reducing energy intake. Weight change up until the 18-24 month period will be measured as a secondary outcome in a cohort of participants who will reach the 18-24 month milestone in the study on or prior to December, 2018. A per protocol analysis will also be applied for comparison of the two weight loss arms. (In addition, weight change will be measured in the participants' AD or retired military personnel partner to test the hypothesis that there is a ripple effect of benefits from the interventions associated with effects in the primary recipients.) The original study plan was to examine weight change over 2 years but due to slower recruiting than anticipated the hypotheses were revised to allow for 1 year to be the primary outcome, with secondary outcomes in the subgroup followed until 18-24 months.
The researchers plan to test our central hypothesis and accomplish the study objectives with the following technical objectives:
1. Conduct a randomized trial comparing the HWL intervention to the CBP intervention over 1 year in adult dependents of AD or retired military personnel. The primary outcome will be weight change from baseline to 1 year. The working hypothesis is that randomization to the HWL intervention will result in significantly greater weight loss over 1 year than randomization to the CBP intervention, and that greater weight loss in the HWL intervention will be associated with greater adherence to the goals of reducing energy intake and hunger.
2. Compare the change in weight loss of participants in the HWL intervention to the CBP intervention over the 18-24 month timepoints in the subgroup of participants who will reach the 18-24 month milestone on or prior to December, 2018. The working hypothesis is that randomization to the HWL intervention will result in significantly improved weight loss retention compared to randomization to the CBP intervention.
3. Examine the effects of the interventions delivered to adult dependents of AD or retired military personnel on the weight of AD or retired military personnel themselves. The working hypothesis, based on preliminary data, is that there will be a "ripple" effect of program benefits from intervention participants to the AD or retired military personnel they live with; specifically, overweight and obese AD or retired military personnel will lose more weight if their partner is randomized to the HWL intervention compared to the CBP intervention, because the weight loss of AD or retired military personnel indirectly exposed to the intervention will be proportional to the weight loss of their adult dependent who is directly exposed.
4. Compare the effects of the two interventions on changes in cardiometabolic risk factors. The working hypothesis is that there will be significantly greater improvements between baseline and 1 year in key cardiometabolic risk factors in adult dependents enrolled in the HWL intervention compared to the CBP intervention, and differences between groups will be predicted by differences in weight loss. For a select subgroup of participants who reach the 18-24 month timepoint on or prior to December 2018, the working hypothesis is that there will be significantly greater improvements in between baseline and 2 years in key cardiometabolic risk factors in adult dependents enrolled in the HWL compared to the CBP intervention.
