Table 1.

Sub-themes and Quotations Within the attitudes component of the Theory of Planned Behaviour.

Sub-theme	Quotation number	Quotations
Awareness of a healthy diet	1	“It is important to have a well-balanced diet because the days that I do not eat well I do feel rubbish about myself, and ill kind of go over what I’m eating and go like ‘oh I’ve not had any fruit or vegetables’” (1,004, female)
	2	“If people are incorporating more plants into their diet then that’s really amazing for their health…I notice a huge change in my mood and energy levels when I do/do not eat in those balanced proportions…I do not function well, and I get anxiety and my mood changes” (1,007, female)
	3	“I’m trying to make a conscious effort of being healthier, em, and yeah just getting fitter and healthier so I think yeah, having a well-balanced diet is key to that” (1,009, female)
	4	“When I eat better I genuinely do feel better” (1,015, female)
	5	“What you eat is basically fuel for your body, and if you eat like really unhealthy things, so like snack a lot, em, for me it tends to affect my mood and how much energy I have, so I think it is quite important for those reasons to have a well-balanced diet” (1,016, female)
Environmental motivations	1	“I think humans and environmental health really goes hand in hand, em, so I see a huge benefit in that” (1,007, female)
	2	“To like reduce meat consumption in general is a good idea, em, I think it is important because it is obviously one of the biggest contributors to greenhouse gases” (1,019, male)
	3	“I think I am motivated obviously by the, like, climate situation and climate emergency at the moment, em, but I am bad myself for just sticking to what I, not necessarily I know because I do, and I have eaten many other alternatives” (1,005, female)
	4	“I’ve seen a lot of stats about how it’s a lot better for the environment to have. Plant-based diet” (1,001, female)
	5	“I also feel quite passionately about its benefits for the planet as well as I think the statistic is that we can reduce our carbon footprint by 73% by going a bit more plant-based” (1,014, female)
Health concerns and distrust	1	“I’ve been hearing of athletes switching to plant-based diets and well, the biggest argument I hear from people against vegan or plant-based diets in general is that it’s not healthy, your lacking certain nutrients” (1,018, male)
	2	“Something I really struggle with in the plant-based world is it just feels like people are spewing out, you know, nutritional info and stats left and right, and I am not convinced that they have a deep understanding of what they are talking about” (1,007, female)
	3	“I’ve heard a lot of cases of taking meat out of a diet and then there’s been health issues associated cause obviously having a well-balanced diet and everything…I would be worried about taking any food group out of my diet without knowing what I need to do in order to replace that so I can still have a healthy diet” (1,009, female)
	4	“I’m weary of plant-based diets because I think there is a lot of disordered eating that the line is very thin there and I think I see a lot of fellow women engaging in plant-based diets and I think sometimes disordered eating is hiding” (1,007, female)
	5	“My dad…he’s always the one telling me to eat less meat…but right now I feel like my goals are different to his, he is thinking more about like longevity and health, where in a way I am thinking more of like performance and like my sports goals that requires eating meat” (1,003, male)
Perception of PBD’s and associated stereotypes	1	“My current understanding of the term is that it’s really just another way of saying vegan” (1,018, male)
	2	“People say it’s just rabbit food and it’s not going to fuel you” (1,013, female)
	3	“The classic stereotype of like a hippie with like long hair or, like does not shave for example, like I think that in some people’s eyes is the stereotype of somebody who follows a plant-based diet” (1,004, female)
	4	“It’s very much ‘you are a tree hugger, or you are a supermodel to get something’, and it’s not just doing it, you know, because you enjoy it” (1,010, female)
	5	“A lot of people have bad stigmas about plant-based diets, like’ oh it’s vegans and vegetarians’” (1,010, female)
Perceived restriction and lack of enjoyment	1	“It just makes me think ew, nah, that’s not for me and I think I would be restricting the types of things I enjoy eating so I decided against it” (1,013, female)
	2	“I’ve not ever really thought of reducing my meat intake because I do really enjoy burgers and curry’s and everything, so yeah, I’ve not really reduced any meat…mainly because I do not want to limit a whole bunch of different options” (1,009, female)
	3	“I also think that you do not want to limit yourself cause there is so much nice food out there to try” (1,006, female)
	4	“Some of the things you can get to fit a plant-based diet does not really taste as good, so I think that is one of the main reasons why I do not like or like I’m not really inclined to switch fully to a plant-based diet” (1,016, female)
	5	“I feel like my dad is punishing himself by following a plant-based diet because I do not think he truly wants to follow one” (1,004, female)
Need for education	1	“At secondary school it’s very much 5 a day and the protein side comes from meat and you never had much else” (1,012, female)
	2	“I definitely think that teaching in schools has a massive impact as it maybe is not like fully understood…I suppose facilitators would be for like government level things that I would think to make plant-based eating and the benefit of it taught about in schools” (1,014, female)
	3	“I think education has a huge part to play as there is a huge stigma around plant-based diets, but it’s also the way that they are done as well, you know, it’s not all peachy” (1,010, female)
	4	“If kids are at a young age and their getting used to seeing things that have non-meat in them…So I definitely think that there should be more advertising and education for more families and children” (1,013, female)