The overall goals of this project are to evaluate the feasibility of web-based nurse-led motivational interviewing and educational interventions to promote healthy behaviours for obesity prevention and maintenance of healthy weight and behaviours among young adults attending university (age 18-29) in Hamilton, Ontario. A secondary goal is to evaluate if the intervention is more successful among people at higher risk of obesity (a risk stratification approach). A pilot randomized controlled trial will be conducted. Young adults will be randomized to receive a tailored behavioural intervention through motivational interviewing sessions with a nurse combined with educational materials, or control (educational materials only). Both groups will be followed for 6 months and their weight at baseline and end of the study will be measured. Outcomes related to the feasibility of the intervention and participants' experiences in the study will also be measured.

Obesity is an established risk factor for many cancer types, including colon, endometrial, breast, and pancreatic. Obesity is complex and treatment is challenging. Thus, primary prevention of obesity is important. This is particularly important now since the COVID-19 pandemic had a profound impact on many obesity risk factors, such as chronic stress, overeating, and physical inactivity. Early adulthood is a key period in obesity development and a critical period for prevention interventions. Young adulthood is a period when Canadians may be highly amenable to healthy behaviour change, develop lifelong healthy behaviours and the primary prevention of obesity may be feasible. Interventions in early adulthood have the potential for primordial cancer prevention (i.e., stopping cancer risk factors before they develop). Despite the known impact of obesity on cancer, there have been few attempts to implement tailored population-based obesity prevention interventions. Obesity interventions must be flexible to address the complex causes of obesity and motivational interviewing may be a successful strategy.

Primary Objective:

1. To determine the feasibility (enrollment, retention, data completion, satisfaction) of a 6-month behavioural and educational intervention to promote healthy behaviours for obesity prevention among young adults.

   Secondary objectives:

2. To determine the effects of the 6-month behavioural and educational intervention, compared to an educational intervention only, on change in BMI, health behaviours (nutrition, physical activity and sedentary time) and mental health (depression and anxiety)

3. To explore whether obesity risk stratification tools identify young adults who may be more successful in an obesity intervention.

Methods: A pilot randomized controlled trial will be conducted. Young adults (age 18-29) attending McMaster University will be recruited and randomized to either the intervention or control. The intervention will include individual motivational interviewing sessions (online or in-person) with a trained public health nurse plus educational materials (based on Canada's food guide and physical activity recommendations). The control group will receive educational materials only. The primary feasibility outcomes that will be evaluated as part of this pilot study include enrollment, retention (≥80%), data completion (≥80% of weights measured, and surveys completed), and participant satisfaction. Clinical outcomes will include weight change from baseline to 6-months, physical activity, nutrition risk, and mental health. Outcomes will be measured remotely using 'smart' electronic scales, activity trackers, and online questionnaires at baseline and every 2 months. Risk stratification will be applied at baseline to identify participants at high risk of obesity (e.g., due to family or personal history). Exit questionnaires will collect data on how participants felt about the study and cost analysis will be conducted.

Our proposed evaluation of the feasibility of an obesity prevention intervention in early adulthood will inform future larger RCTs for obesity prevention. The results of this study have the potential to directly contribute to the primary prevention of several types of cancer by testing an intervention that could be scalable to public health, post-secondary education, or primary care settings.

Inclusion Criteria:

• English speaking, and capable of providing informed consent
• McMaster University students 18-29 years of age
• Body mass index of at least 18.5

Exclusion Criteria:

• Physical and mental health conditions that would be contraindicated for a weight management intervention, including eating disorders, pregnancy, cancer, or medications that affect body weight

For this pilot study, individual data will not be available.

A total of 101 participants were randomized (52 to the Motivational Interviewing group, 49 to the No Motivational Interviewing group). One participant withdrew from the No Motivational Interviewing group before completing baseline characteristics, resulting in 100 participants. analyzed at baseline. For race/ethnicity participants were permitted to select "all that apply".

6 months

Any untoward or unfavorable medical occurrence in a participant, including any abnormal sign (for example, abnormal physical exam or laboratory finding), symptom, or disease, temporally associated with the participant's participation in the research, whether or not considered related to the participant's participation in the research.