Interview with plant-based nutritionist: How climate-friendly diets benefit your health
Updated: May 26
Recently I had the pleasure of chatting with plant-based nutritionist Callum Weir from Yumfu. Callum is a certified nutritionist, educational speaker, and host of Plant-Fuelled Podcast. He helps people transition healthily to a plant-based diet with evidence-based advice and recipes.
Eating more plant-based food as part of a climate-friendly diet can bring up many health questions: Is it safe for my health conditions and fitness goals? Can plants give me all the nutrients and protein I need? Are there any surprise health benefits of eating plant-based food? We spoke to Callum for answers.
Speaking to Callum was absolutely fascinating. He exudes passion for science and making it as simple as possible to eat more plants. He's also kindly shared two nutritious and sustainable recipes for you and tips to create healthy, balanced meals yourself.
Founder of Yumfu
🎙 Listen to the Plant-Fuelled Podcast
Here's our conversation. You can read the questions that Callum had for me about climate-friendly eating, too.
Why did you decide to become a plant-based nutritionist?
For me, I always wanted to go on that route of being vegan. I was vegetarian once and then pescatarian. And I always, kind of, didn't know whether it was the right thing to go vegan because you hear all these horror stories being like: "Are you gonna get the right nutrients? Are you gonna be able to thrive and get all the protein and iron?" Everybody's asking, "are you gonna get these" and it kind of it's a bit detrimental to how you're gonna feel in yourself. So I was like, you know what, I'm gonna go research this myself, just so I know what I'm doing is to the best of my ability. Before [...] the nutrition research came out, I switched over for the animals. Whether it's good for my health or not, this is where I'm going. And it just so happens that the nutrition came with it. I delved straight into nutrition and was like, "let's find out what you're taught in schools and what you're taught in the media", and just see how it differs. And then you go into plant-based nutrition, and you realise everything that you've probably been taught is very biased towards the meat industry.
So I was kind of like, "Oh, I need to delve more and more into this". And years later, I'm still delving now. There are still bits and pieces I'm finding out daily. It was one of those things that I needed for my own mindset: to know the nutrition and to make sure I was thriving to the best of my ability. And then, I could help other people as well. The thing is, the information is out there. It is readily available, but it's just sifting through everything to find it. This is kind of why I've gone into nutrition myself, into a business, so I can sift through the information for other people and make it easily accessible and easily readable.
You don't want the scientific lingo because nobody's going to understand it; I hardly understand it! So [making] sure everybody can read it, we can start making impactful changes throughout the world.
It sounds kind of a similar journey to us. There's a lot of information out there. You just want to make it easy to understand and digestible.
That's the thing. There is so much evidence out there and so much misinformation as well that people will take what they see first and not take any of our information. So you need to get it as easily as possible in front of people for them to understand.
One of the things you've talked about is protein. We know that reducing the amount of meat on our plates is an easy way to reduce the carbon footprint of your food.
But many people who are reducing meat in their diet might be worried about not getting enough protein. Is this something that we should worry about?
Not many people realise that protein actually originates in plants. Every plant on this planet has protein. So, animals then feed on these plants to get protein, [and] then we consume the animal and get protein. But it's recycled and built up over time.
I go straight to the source. I get my protein from a whole foods plant-based source. Other people go for vegan processed foods, and that's fine as well.
What we need to realise is that there are 20 amino acids altogether, which are the building blocks of our body and which count as proteins. 11 of those [amino acids that] we need, we don't need to get from our diet as they get made by our body. Nine we have to get from our diet. You can get any of these nine amino acids from various plants.
Sometimes people say, "Oh, it's not a complete protein". The thing with complete protein is that an incomplete protein doesn't mean it's missing any amino acids. They're just in various quantities, just like vitamins and minerals.
If you were to eat something like kale, it would have more calcium than it would iron. And it's the same with protein.
Let's say, hypothetically, you ate something like a carrot. There are nine amino acids, and eight of them might be 100% of what you need, and one of them might be at 80%. That's then classed as an incomplete protein. There are still amino acids in there; it's just a lower quantity.
But obviously, we're not just eating that food on its own. We're mixing it with other food as well.
So let's say I mix the carrot with mushrooms. Mushroom is an absolute powerhouse for protein, and the amino acids at 100% would get topped up. Then ones that are are at 80% would also get topped up to become 100% or more. Then you've created a complete protein together.
If you're coming from a very meat-oriented diet, working around these ratios may feel a bit iffy at first because you're not too sure where to get these protein requirements. But they're very easily sourced, and – to be fair – if you're getting enough calories in your diet, you're getting enough protein.
Most people are eating more protein than is required for their bodies. Our bodies only need your body weight in kilograms x 0.0009. If somebody weighs 11 stone [~69kg], that's around 60 grams of protein per day.
In three meals, that is very easily done, especially if you have oats in the morning. A cup of oats has 11 grams of protein; then you're adding everything else like seeds, nuts, peanut butter, etc. So you don't really need to worry about protein unless you're looking specifically to become someone like a bodybuilder.
We see ready meals and snack bars marketed with 20g of protein in supermarkets. So based on what you've said, is it fair to say, in most cases, that people don't need them?
Yes, you don't overly need them. If you're going to go get a protein bar, for instance, that says 20g of protein, that's great. But if you eat them with three meals that have already consisted of 60g of protein, and you don't have any goals, then there's no reason for it.
Most of these are marketed very well, but when you look into it on the back, these bars have 20g of protein, but most of the calories are coming from fat. You have to look into that more and realise that it's very low in protein compared to the fat ratio.
What tips do you have for someone who's transitioning from a meat-rich diet to eating less meat or eating plant-based?
Do it slowly! Don't jump in and do it straight away. The idea of jumping onto a whole foods plant-based diet overnight is great, but it's not sustainable if you have no idea what you're doing.
If you've researched it beforehand, then, yes, go for it. But if you have no idea and you're just gonna go with it, you need to make those small changes over time.
If you're going from a very meat-oriented diet too, then jump onto vegan junk foods, so it's something similar to what you've had before. They are a middle ground, though; you shouldn't be on those for everyday consumption. Just like you shouldn't be eating red meat every day. There are going to be health risks as well.
So, slowly transition and then veganise the food you love. For instance, [if] you love Chilli con Carne.... in your chilli, you have beans, mince, chopped tomatoes, spices, herbs, whatever else you like. Replace the mince and put lentils in.
Then everything else is exactly the same. There's nothing else different about it, apart from there's no mince and lentils instead. When you simmer [lentils] down, they have a kind of a softer texture, much as you would get with mince. And you've slowly veganised the meal. You could do the same with Shepherd's Pie.
Then just find these alternatives and, after a while, you realise you can be doing this all the time. So, on a Monday, you can have a meat-free Monday. You could do a meat-free Wednesday and then a meat-free Friday until you get the hang of it. Then start transitioning those other days.
Even just changing your breakfast, for instance, is the best way to do it, because breakfast is so easily changed. If you have a bowl of porridge, it's not so different; just change the milk. Everything else is exactly the same because nobody's having meat on their porridge!
Work on those slight transitions, even if it's breakfast first, and then maybe for lunch, have a Buddha Bowl. And just find things that work for you, but don't do it overnight because you'll be in for a hell of a ride when it goes wrong.
We know that a plant-based diet is better for the climate. What are some of the health benefits of going plant-based?
Benefits... I could be here naming them forever! First of all, a lot of people struggle with high cholesterol, or they consume too much cholesterol. Luckily, plants don't have cholesterol.
So, if anything, we're always going to be lowering that high cholesterol, which leads to plaque, which can lead to artery blockages that cause heart attacks and strokes.
You're reducing the risk of heart disease because you're not consuming overly saturated fats. You're not consuming too much iron because, although iron is great for us, our bodies don't know how to stop absorbing haem iron (which is animal iron).
Because we don't know how to stop absorbing it, it then creates an iron overload which clogs up our bodies and creates various issues throughout our arteries, veins, heart, and liver. So, for heart disease, we've lowered that risk on a whole foods plant-based diet.
You're also reducing things like Alzheimer's disease and cancer. Everyone knows somebody who struggled with Alzheimer's or cancer. You're reducing those risks by eating a whole food plant-based diet because you've got all those antioxidants fighting off free radicals inside our bodies.
Antioxidants are the good guys that are helping clear away toxins in your body, and everything is slowly getting better so your heart can beat, your lungs can breathe, and your brain can function to the best of its ability. There are lots of benefits and reasons to try a plant-based diet.
Meat, especially red meat and processed meats, heighten the risk of many different cancers because of their carcinogenic properties. The World Health Organization has red meat as their number one carcinogen, alongside smoking, with attribution to cancers.
Is there evidence to show that a plant-based diet is associated with weight loss too?
There is. When it comes to weight loss, what we're doing here is eating a majority of whole plant-based foods. These are very anti-inflammatory, so we are reducing our body's inflammation properties which will start to cut down our body fat. It's only slightly, and not by much, but that's just the inflammation.
Then we go with calorie density. So, for instance, let's say a chicken breast is 500 calories. We go for plant-based whole foods, which is to say half a cup of black beans, half a cup of broccoli, half a cup of lentils, some chopped tomatoes, some mushrooms, let's say some spinach. That would also accumulate to 500 calories.
The calorie density is a lot lower, so you can eat a substantial amount more, feeling fuller for longer, with fewer calories.
What you could eat in, let's say a steak, rice, and a few other bits, would come to about 1600 calories, at most. With plants, you can get in a whole breakfast, a whole lunch, and a whole dinner with 1600 calories. So you feel fuller for longer, but you've also got fibre which promotes weight loss.
You're also eating water in foods, which promotes weight loss as well. With the whole foods you consume, you're filling that gap inside you as well as feeding your body the nutrients you need so you don't start getting hungry.
The reason people feel hungry an hour later after, let's say, a Chinese takeaway, is because that food is taking away the minerals from our bodies. We're then wanting to revitalise. Our body's like, "Oh, we're hungry, we're hungry, we're hungry! We need this! We need more nutrients!". And then we just feed it with something else, let's say cookies.
Whereas with whole foods, for instance, you're just feeding it more and more vitamins and minerals, so it's always been rejuvenated. It's always being looked after, and it's always being vitalised with the nutrients it needs, which will help fill up for longer.
Weight loss has some benefits around links to obesity and the risk factors that are associated with diabetes, too, right?
One of the benefits is cutting Type 2 diabetes. It's virtually impossible to get Type 2 diabetes on a whole foods, plant-based diet. If you have it already, you can reduce and reverse it.
So, when we talk about whole foods, it's the vegetables, not the junk food and substitutes that you can go and get?
I would love to say that these meat substitutes and such are amazing for the body. But you know, an Oreo is vegan, and we all know they're not great for us!
So, as much as most of these things are promoted as the healthy option, there's nothing healthier than eating a plant in its whole form with its fibrous properties.
Is a plant-based diet for everyone? Can you follow it if you have allergies, if you're pregnant, or if you do a lot of exercise?
Yeah, absolutely. There is nothing that I've seen within the research and from speaking to other physicians and dietitians as well... There's nobody on this planet that can't follow a plant-based diet.
If you're an athlete or a bodybuilder, yes, you can go plant-based. There's been shown to be so many benefits for the body going plant-based. This also goes back to protein. There are so many plant-based bodybuilders, so proteins aren't an issue.
The same with athletes. Some of the most active ultra-runners on this planet are entirely plant-based. So, athletes and bodybuilders don't have to worry.
Obviously, for people that are looking to go plant-based that are pregnant, there's gonna be some minor tweaks that you need to make that you wouldn't normally do. You're upping your body to take on nutrients for two people instead of one.
So, things like your iron and folic acid need to be risen. Some supplementation may need to happen for some nutrients. But that's only if you can't fit in when you're hungry.
When you're pregnant, there are things that you're not going to want to eat. There are things that you're going to really love to eat.
So, if you can't fit things in, like if you've eaten a hell of a lot of iron, but you still haven't made it up to the 37 milligrams, which you need when you're pregnant, then an iron supplement might be beneficial.
The same with omega-3. It might be beneficial to take an omega-3 supplement, but it's not always necessary.
But allergy-wise, there are not many allergies that will stop you from eating [a plant-based diet].
Gluten; many foods don't have gluten in them, the majority of plant foods. Let's say you're allergic to a certain vegetable; you don't have to eat it.
If you're allergic to soy, we don't need soy in our diets. We can, but we don't have to. You can happily live a plant-based diet without soy. It's just in a few products like tofu and tempeh.
There's no specific allergy that would stop you from living a plant-based diet, it would just be changing a few bits and pieces around—tweaking to you. Tweaking to your body and your genes.
I guess that someone like you can help people figure out how to make those tweaks in their diet too?
Absolutely. Let's say, for instance, you were allergic to soy, then we can do everything we can to base your diet around not eating or consuming anything like that, but still having a very fulfilled nutritious diet eating various other foods.
When you're creating plant-based recipes, what do you look for? How do you know if they're going to be nutritious or balanced enough?
I start with macros. For instance, I'm making a buddha bowl. I will start with my [carbohydrate] source; sweet potatoes, brown rice, whatever you want it to be.
You need something for your energy – and carbs are energy. Most of the time, those carbs hold various nutrients, so then you're building up those nutrients – minerals and vitamins – throughout the day too.
Then add a protein source. So that may be tofu, tempeh, [or] black beans (which will also kind of count as another carb source). Then you're building up nutrients and vitamins and minerals again.
Then [a] fat source, which might be avocado, it might be a few little nuts or a sprinkle of seeds. Nuts and seeds have an abundance of protein in them, as well as things like selenium, magnesium, and manganese. So you're slowly building these vitamins and minerals we need in our diets.
Now you've got your carbs, your fats, and your protein. Last, we want omegas. You always want a bundle of omegas as well. We don't want to forget those because that is our brain's health and our heart's health.
Again, nuts and seeds are full of omegas for conversion to different omega sources.
Then we've kind of got those into a bowl and realise what we haven't got. Let's say we want some more vitamin C foods because that's going to be good for iron-rich foods like black beans. We have vitamin C in red pepper, for instance, which will help absorb iron.
The main thing is researching where your food is coming from so you know exactly where your minerals and vitamins are coming from. Every single one of my meals has to have at least a small percentage of all vitamins, all minerals, proteins, fats, carbs, and omegas.
If it doesn't contain one of those, I have a snack afterwards like an apple for vitamin C, and I don't have caffeine before or after because it stops the absorption of many minerals and vitamins!
Nutritious and Sustainable Plant-based Recipes
Yumfu's Lentil Bolognese Recipe
Yumfu's Red Cabbage and Potato Soup Recipe
What other questions do you have about a plant-based diet? Let us know in the comments below 👇