Motivations for participation in weight loss clinical trials

Males are under‐represented in weight loss clinical trials, usually comprising fewer than one‐quarter of participants. Our study aimed to investigate people's motivations for participating in weight loss trials and determine any relationship with gender. Eighty individuals from an existing registry for weight loss trials were contacted, of whom 24 (9 males, 15 females) agreed to participate in a 20‐min semi‐structured interview around their expectations and motivations for volunteering. Interviews were audio‐recorded and transcribed in Zoom. A transcript of each interview was uploaded into NVivo for preliminary thematic analysis. Improved health was a common motivation for pursuing weight loss in all subjects regardless of gender. Male recruitment to weight loss trials was often influenced by advice from a healthcare professional to lose weight for the prevention of obesity‐related comorbidities, whereas family and aesthetic expectations (e.g., clothes and fashion) were key elements of female participation. Identification of gender differences in motivations for volunteering in weight loss trials will help improve tailoring of recruitment strategies and interventions to enhance male participation in the future.


| INTRODUCTION
Most of the health research literature makes use of quantitative methods, which are inherently limited in their ability to account for the complexity of unique human experiences. Qualitative approaches are becoming increasingly common in public health research, though subsequent thematic analysis needs to be rigorous and relevant to maintain credibility. 1 In the context of weight loss, qualitative analysis helps us to understand the personal experiences of individuals, 2,3 as well as how 'responders' and 'non-responders' differ in responses to various regimens. 4,5 However, qualitative studies on weight issues are still in their infancy and few have explored motivations for weight loss in individuals living with obesity.
Desires to improve health, as well as influences from family and friends are hypothesised motivators for weight loss. 6,7 While there have been qualitative investigations into weight loss pathways for males [8][9][10] and females [11][12][13] separately, there is a lack of qualitative research assessing differences in motivations for weight loss based on gender. A Spanish study assessing male and female perspectives on weight loss interviewed two focus groups. 14 They found gender differences in obesity prevention strategies, reasons for weight gain and motivations for reducing weight. 14 Males were reported to lose weight for health reasons while females had additional desires for aesthetic outcomes. 14 Another qualitative study that did not have a gender focus still analysed their results separately for males and females because they recognized differences between these biologically different populations. 15 They reported that females demonstrated greater concern about excess weight and were more likely to engage in obesity prevention programs compared to males. Differences between males and females concerning obesity management emphasizes a need to consider these unique perspectives in the development of prevention and treatment strategies.
Semi-structured interviews are the most common approach utilized in qualitative research within healthcare. 16 Key characteristics include a loose flexible structure with iteration, gathering information from individual perspectives and a deep exploration of their thoughts and experiences. 17 The use of open-ended questions with follow-up probes is an effective method of obtaining qualitative data due to its potential to unveil information about personal and sometimes sensitive issues otherwise difficult to obtain. This technique enables a deeper understanding of the intricacies of individual variation.
The concept of 'thematic saturation' (i.e., no new emerging ideas) as described by Glaser and Strauss 18 was previously the accepted norm for ceasing data collection in qualitative research. However, much controversy surrounds its subjective use in defining sample sizes, in particular problems with generalizing findings that arise using a thematic saturation approach. 19 A more recently accepted method for defining sample size is the concept of 'information power,' considered to have greater relevance when selecting participants and sample sizes for a qualitative study. 19 According to information power, the more information a sample holds (relevant for the actual study), the lower the sample size required. This means that studies with narrow aims and a specific population will require a smaller number of participants. 20 Well-conducted qualitative studies with sufficient sample sizes can address gaps in knowledge regarding differences in motivations of males and females who volunteer for weight loss trials. Gaining insight into these nuances will improve recruitment and maximize weight loss outcomes according to the distinct needs of males and females. An improved understanding of motivations to participate in weight loss trials will aid in new intervention designs that are more attractive to all participants.
The purpose of our study was to identify gender differences in motivations of participating in weight loss trials and determine if these explain the unequal representation of males and females. This gender discrepancy is an established research gap in weight loss research, with low male recruitment a recurring issue that needs to be addressed.

| MATERIALS AND METHODS
Semi-structured interviews were conducted between July-August 2022 and involved the following: developing interview guidelines, ethical considerations, planning logistics, identifying participants, conducting interviews, establishing trust and rapport, and finally thematic analysis. Ethical approval was granted by the Sydney Local Health District Ethics Review Committee (RPAH Zone).

| Participant recruitment
Participants were eligible if they resided in Australia, were 18 years or older, and provided their details to the Boden Clinical Trials Register at the Charles Perkins Centre, University of Sydney, by expressing interest in volunteering for a weight loss trial. Another requirement for the registry was that volunteers had to have a body mass index (BMI) of more than 25 kg/m 2 .
Participants were invited to the study via email. An information sheet was provided along with the researchers' email addresses to address any questions or concerns. Recruitment was conducted in two phases ( Figure 1). Forty individuals were invited in bulk from the registry on two separate occasions, equating to a total of 80 people (41 males, 39 females). A total of 24 individuals agreed to be interviewed. Those who declined were not contacted again.
Reasons for non-participation included lack of time, no personal benefit, or satisfaction with another weight loss regimen. Of the 24 volunteers, 9 identified as male and 15 identified as female (including one transgender female). Participants in this study were not paid an honorarium.

| Definition of gender
We acknowledge that gender is a tenuous social construct. In this study, we defined gender according to how the participants chose to identify themselves, which may or may not be the same as their biological sex.

| Planning logistical aspects
Interviews were conducted using Zoom using the in-built audiorecording and transcription mechanism. Testing of recording equipment was carried out prior to the interviews. We used one interviewer throughout to ensure consistency. All interviews were carried out in a quiet, private location to avoid interruptions, scheduled at a time determined by the participants.
Verbal consent was obtained before interview commencement, with opportunities to express concerns or ask questions. Participants were informed that the interview would be audio-recorded and reminded that they could refuse to answer any question and withdraw at any time.

| Establishing trust and rapport
The interviewer's approach was friendly and non-judgemental, with use of a warm, conversational tone to ensure participant comfort.
Non-verbal cues such as pauses, silences while listening, and smiles and nods where appropriate, were used to encourage further elaboration. Where possible, the interviewer repeated language used by the participants to encourage them to share as much as possible in their own words.
Audio-recording was necessary for the interviewer to concentrate on building rapport rather than being distracted by note taking. The interviewer used video to aid in active listening. While video was not mandatory for interviewees, those who opted to keep their camera on provided helpful social and non-verbal cues of body language and gestures to the interviewer.

| Thematic analysis
Thematic analysis is a common approach for identifying patterns or themes present in qualitative data. [21][22][23] The process of thematic analysis is flexible because it is not bound by any theoretical or epidemiological views. 22 We utilized an inductive approach using NVivo software to initially identify low-level key themes (initial codes), followed by manual coding of higher-level themes, in accordance with Braun and Clarke methodology. 22 Our coding included themes specific for each interview question. After stratifying the transcripts by gender, we identified common themes based on a COM-B framework of behavioural change. 24 The COM-B model states that an individual must be physically and psychologically able (C) and given an opportunity (O) to exhibit desire (M). 24 Researcher positionality was managed reflexively, using personal experiences and values to make sense of the data. This approach ensures accountability, trustworthiness, clarity and personal growth in thematic analysis.

| Generating interest in weight loss clinical trials
Participants described various ways they found out about the weight loss trial registry, which included their general practitioner, advertisements on Facebook, flyers at the pharmacy or general searches conducted online. Some were uncertain how they discovered the trial  After hearing about participants' weight loss journeys, an emerging theme was the impact of COVID-19. Many mentioned experiencing substantial weight gain during the pandemic, alongside unsuccessful attempts to lose weight during lockdowns and difficulty to maintain a healthy diet and exercise regime afterwards. One person said, 'I've definitely put on more weight the past few years, due to lockdowns and things'.

| Support of family and friends
Most participants did not inform their family and friends the registry.
These individuals explained they would share this information with their family and friends after confirmation of the trial. For those who discussed the registry with their family, it involved a female mentioning it to her partner, rather than a male mentioning it to his partner.

F I G U R E 2 Script including semi-structured interview questions and follow-up prompts.
Females responded saying, 'as long as I'm happy, he's happy' and 'if I want to do something he's fine with that'.
All interviewees were sure their family and friends would be supportive of them engaging in a weight loss trial, conveying these feelings through use of words like 'definitely' and 'certainly' with a strong affirmative tone.

| Expectations from participation in clinical trials
The most common expectation from volunteering in a weight loss trial was health-related benefits, expressed unanimously by both genders.
However, the way these expectations were expressed differed for males and females. Whilst some females specified a weight loss goal, this was less frequently reported compared to males. Many females hoped losing weight would help them keep up with their children. Other females expected that weight loss would allow them to achieve healthy pregnancies in the future.

| Perceived benefits of weight loss trials
The majority of participants said a perceived benefit of weight loss was to 'feel better' about themselves. However, the meaning of these responses differed for males and females.

| DISCUSSION
This qualitative study demonstrates a range of gender differences in motivations for volunteering in weight loss trials. Current literature regarding weight loss is primarily female focussed, which could be because they are considered to have greater weight concerns. 16 Perpetual under-representation of males in weight loss clinical trials is another likely contributor, as most research has been performed in predominantly female cohorts. Negative attitudes towards weight have been correlated with lower levels of self-perception for both genders, but this relationship is reported as significantly stronger for females than males. 25 In our study, Facebook advertisements were more effective in female recruitment to the registry compared to males. This might be because females access social media more frequently than males. 26 Therefore, targeted approaches towards males should utilize other measures and not limit advertising to social media. This could involve advertisements in areas males tend to visit more frequently, such as fitness gyms or the walls of public bathrooms. Photos of healthy and achievable masculine body physiques as part of these advertisements may assist in making weight loss trials more desirable and relatable for males.
The females in this study more frequently shared information with their partners about volunteering for a weight loss trial than their male counterparts. Improving information exchange for males with their partners could generate greater support and encouragement towards weight loss. For example, the DIRECT-Spouse study 27 showed that males whose partners participated in group support sessions lost significantly more weight over 6 months than those whose partners did not. Evidence from family studies shows benefits when weight loss strategies are taught to both parents and children. 28 Future weight loss trials could invite participants' family and friends to attend group support sessions, which might enhance motivation and accountability for the individual's weight loss journey.
This study showed that in general, males are motivated by individual weight and BMI goals (often recommended by their doctor), whereas females tend to be more family oriented. The SHED-IT pilot study 29 which exclusively targeted males suggested they value simple messages with a clear focus on weight loss. Shorter messages with an emphasis on weight-related goals could be more relatable for males and increase their chances of being recruited to weight loss trials.
Additionally, it has been shown that doctors' empathy towards the family circumstances of female patients results in greater weight loss. 30 In this study, females desired aesthetically driven goals such as more clothing and fashion choices. The association of being slimmer and feeling more confident in clothing is well-established. 31 Therefore, a focus on family and aesthetic outcomes is likely the best strategy for acquiring female volunteers, though females are already well represented.
There are some limitations to this study. We invited more males than females to participate yet recruited a greater number of females (n = 15) compared to males (n = 9). This outcome mirrors other studies that report females as more likely to join weight loss trials. 32 Our sample size (n = 24) was modest, but according to the concept of information power, still sufficient for our answering our research question. 19,20 Our sample is probably representative of a middle-aged working population or retirees since these groups are more likely to be exposed to advertising or have sufficient time for volunteering in a weight loss trial. However, this is not backed by evidence since the exact age of our interviewees was unknown. Therefore, there may or may not be an age bias in our sample, and if this is the case our findings may not necessarily be transferrable to a general population.
However, the sample we interviewed is likely to represent the demographic that tends to volunteer in weight loss trials.

Strengths of this study included the open-ended questions with
follow-up prompts that facilitated depth of participants' responses, whilst avoiding a longer interview duration that would likely deter voluntary participation. The use of Zoom meant interviewees could dial in at a time and place convenient for them, which may have assisted with obtaining genuine, authentic responses. 26 An unexpected benefit from this study was participants' renewed motivation for weight loss. Therefore, this first point of contact appears to be a key steppingstone towards facilitating effective future engagement. It was encouraging that every participant expressed willingness, excitement, and eagerness towards a future clinical trial after discussing their weight loss goals during the interview.
This qualitative study reveals key differences in motivations behind male and female participation in weight loss trials. Of importance is the need for improved recruitment strategies to engage males in weight loss programs as females are already well targeted. Moving forward, researchers and healthcare professionals should seek to develop more tailored approaches that relate and appeal better to male interests so that a more equal representation of both genders in future weight loss clinical trials can be achieved.