An upcoming trial will implement a weight loss program for couples to investigate how individuals affect their partner’s weight loss.
Weight loss studies up to date have focused on the individuals within a couple, but couples as a whole engage in the same dietary and physical activity habits and thus share a similar obesity risk. This social component to weight loss led researchers to examine the potential of a weight loss program for couples based on the Self-Determination Theory. This theory states that environments suited to supporting the needs of an individual foster the growth of autonomous, competent individuals. In a study protocol recently published in BMC Public Health, researchers discuss that they will apply this theory to cohabiting couples to examine the influence individuals have on their partner’s weight loss.
To obtain participants, the researchers plan to advertise in the local media, then screen individuals via a phone interview. Those eligible for participation must be couples aged 18-70 years, with a BMI measurement of 25-45kg/m2 who live together. Participants cannot be engaged in efforts targeting weight loss such as special programs or taking supplements, cannot be pregnant, lactating, have certain cardiovascular issues, abuse substances, or be undergoing treatment for cancer.
Researchers will then randomly assign couples to one of two groups: the Self-Determination Theory-Weight Loss (SDT-WL) group and the Behavioural Weight Loss (BWL) group. Those in the SDT-WL group attend weight loss meetings every week for six months, receive basic information about healthy eating and exercise, as well as training on how to support their partner by reinforcing partnership, using supportive language, and overall acknowledging and responding to their partner’s needs. The BWL group will also attend weekly weight loss group meetings for six months and receive basic nutrition and physical activity information, but will not have training on partner support.
For the trial, participants will reduce their dietary fat intake by 30%, but maintain caloric standards. In order to do so, all groups will receive a sample meal plan, nutrition guidebook, and links to online resources. Additionally, researchers will encourage the gradual increase of physical activity until participants are engaging in 50 minutes of moderate intensity exercise 5 days per week. Dietary choices and exercise will be tracked either in the provided diary or a preferred online application or website. A variety of self-reported questionnaires and scales such as the Important Other Climate Questionnaire, Sallis Support Scale, Quality Marriage Index and Revised Dyadic Adjustment Scale will be used to measure and assess how well each individual feels their needs are met by their partner and how they feel about the dynamics of their relationship during the trial.