Is a flexitarian diet healthy & environmentally sustainable?


Flexitarianism offers an easy way to achieve fast decarbonisation and has the added benefits of contributing towards improving not only the biophysical health of the planet but also that of its human habitants.”                                                                                      Raphaely & Marinova, 2014

It is no secret that I’m a strong advocate for a whole foods plant-based diet: to me, the evidence pointing to its health and environmental benefits is simply too undeniable to dismiss. However, I’m also a realist: I know that not everyone is willing to give up their animal-based foods – not straight away anyway. After all, diet is so much more than just ‘food’. Indeed, since the beginning of time, humans have felt the desire to be part of a tribe and in 2019, religion aside, the dietary framework that one adopts and follows is often one of the most defining aspects of our identity.

Taking this into account, I’m not at all surprised by the amounts people who decry a dietary framework (vegan) that does not allow for their mother’s homemade lasagna, their friend’s BBQ meat or the milk & cookies they’ve grown up on. It was precisely out of these considerations that a flexitarian diet was born. Designed as a diet “for people who know that vegetarianism is one of the healthiest and smartest ways to eat, but don’t want to sit in the corner at a BBQ with an empty bun”, flexitarianism has been gaining traction in recent years. Flexitarianism allows for individuals to consciously reduce their consumption of animal-based foods without the strict parameters set by other dietary frameworks. Generally, people are drawn to a flexitarian diet because it grants them the flexibility to give up meat for the most part – yet still indulge in it from time to time without any associated guilt. Whatever their motivation, the adoption of this dietary framework generally results in a highly reduced consumption of meat and animal-based foods. Based on this, I think there is a STRONG case for the promotion of a Flexitarian diet to the masses. For those with strong ethical views about animal cruelty, hear me out. Let’s start by defining a Flexitarian diet and then work through why I think the promotion of this diet has merit.

In this article, I will answer: 

  1. What a flexitarian diet is & its origin 
  2. Whether a flexitarian diet is healthy 
  3. Flexitarian diet & climate change impact 
  4. Tips for implementing a best-practice flexitarian diet 
  1. What is a flexitarian diet 

A flexitarian diet, also referred to as a semi-vegetarian diet, had originally been defined as a predominantly vegetarian with the occasional inclusion of meat or fish. The term, first coined in 1998, originally described people who mostly, but don’t always, eat vegetarian foods. Practically, a flexitarian has been described as one who may consume dairy and eggs regularly, with the occasional inclusion of a meat-based dish. 

However, it appears to be that the definition of this dietary framework is also highly flexible and subject to interpretation: in fact, there appears to be little agreement on what a flexitarian diet really is. While the most recent IPCC report quantifies it as a diet which replaces 75% of animal foods with plant-based foods, other studies have defined a flexitarian as one who is completely vegan 2 out of 3 meals each day. This discrepancy, logically, makes it hard to objectively state just how many merits this dietary framework affords in terms of health promotion and climate change mitigation potential. Regardless, the common denominator amongst all definitions is that the consumption of animal-based foods is significantly reduced.  

One thing that is clear, however, is that this dietary framework is no fringe movement: the flexitarian diet is the diet that the EAT-Lancet Commission Report on Healthy Diets From Sustainable Food Systems sees as the one with the most potential for reducing the burden of food-related disease and the food-related environmental burden. In fact, their ‘planetary health diet’ with the potential to save 11 million deaths each year, is one that is largely plant-based but can optionally include modest amounts of fish, meat and dairy foods – in other words, a flexitarian diet. 

The good news here is that while keto, carnivore, and paleo diets may have been making a lot of noise, it appears that flexitarianism has quietly been gaining ground in the background. Research has estimated that 70% of the Dutch population and a third of US Americans and Britons identified as flexitarian. [13] As more and more people realise the impact of meat-heavy diets on their health and that of the environment, coupled with the recent boom in plant-based alternatives that do not compromise on taste, this rise makes total sense. 

2. Is a flexitarian diet healthy? 

While I appreciate the flexibility of this dietary framework and strongly believe it may prove to be an effective tool in reducing the health and environmental burden of our global food choices, I question: just how healthy is the occasional inclusion of animal foods? In other words, how much worse for our health would it be to occasionally include meat, dairy or fish compared to never? 

Long term studies on flexitarian diets and human health are sparse, and the only systematic review I’ve come across that aimed to assess the evidence of this diet on health outcomes was written by the controversial nutritionist Emma Derbyshire (you might remember her from her Choline fear mongering piece which I wrote about here) who received funding by Quorn Foods (the makers of plant-based meat alternatives) for the writing of the paper. Therefore, its findings that a flexitarian diet is a healthy diet with the potential to reduce rates of weight loss, metabolic health, and diabetes prevention must be taken with a pretty large grain of salt.

Regardless, as noted above, one of the biggest issues in looking at the totality of the evidence on flexitarian diets is that there simply is no agreed-upon definition of what this diet consists of. For example, a trial carried out by Baines et al. [4] defined a flexitarian diet as one which excluded red meat but included poultry and fish, whereas the trial by Tantamango-Bartley et al. defined it as a diet inclusive of red meat, poultry and fish on occasion with regular consumption of eggs and dairy. [5] These discrepancies make it extremely hard to determine with precision the health implications of including the occasional animal-based meal in one’s diet. Obviously, someone who eats red meat once a month versus someone who eats it once a week or even once a day will have significantly different health outcomes. 

Still, the evidence seems to suggest that any reduction in the consumption of animal-based foods yields a corresponding benefit. In the Adventist Health Study 2 which looked at Vegetarian Dietary Patterns and Mortality in more than 73,000 participants, researchers identified lower rates of mortality in vegans, vegetarians and pescatarians compared to semi-vegetarians (essentially flexitarian) and non-vegetarians. However, it is worth noting the semi-vegetarians had 8% lower risk of premature death than the non-vegetarians, suggesting it is a step in the right direction [6]

These conclusions are consistent with the findings of the study on vegetarian diets and incidence of diabetes in the Adventist Health Study-2. [7] Following more than 41,000 participants, this study carried out by Loma Linda University found that every reduction in animal consumption was associated with a relative drop in rates of diabetes. Even after controlling for BMI and other confounding variables, the incidence of diabetes increased incrementally from vegans, lacto ovo vegetarians (dairy + eggs), pesco vegetarians (fish >1/month + dairy + eggs), semi-vegetarians/flexitarians (dairy + eggs + meat and poultry more than 1/month but less than 1/ week) and to non-vegetarians.

Lastly, an interesting study out of Switzerland recently modelled the health, nutritional and environmental consequences of various dietary frameworks scenarios. [8] According to their modelling, if all Swiss people adopted a vegan diet, 20,986 DALYs (the number of years lost due to ill-health, disability or early death) could be saved. A vegetarian diet yielded a 8049 reduction in DALYs, a pescatarian diet 10,679, and finally, a flexitarian diet (defined as predominantly plant-based with the occasional inclusion of animal products) reduced DALYs by 5259. Interestingly, but unsurprisingly, the protein-oriented and meat-oriented diet scenarios both resulted in a 23,699 and 24,788 INCREASE in DALYs respectively. In other words, the vegan diet yielded the highest reduction in the diet-related burden of disease, followed by the pescatarian, vegetarian and flexitarian – while the protein-rich animal-centred diets performed the worst. 

Overall, I think that in order to answer whether a flexitarian diet is healthy we have to look at it in context: is it healthy, compared to what? For someone coming from a standard western diet rich in dairy, eggs and meat, a flexitarian would naturally be a great improvement. To these individuals, a flexitarian diet may offer a palatable and easy-to-implement transition that would undeniably improve their health while most likely ensuring all nutrients are adequately sourced. But for those who have already successfully removed animal products from their diet –  I see no reason why they should add the occasional animal-based food given that the totality of the evidence supports the health-promoting and disease burden potentials of a plant-based diet (provided they are supplementing correctly and sufficiently).

Despite the confusion generated by the food industry and propagated by the media (and Instagram), we have always known that plant-based whole foods are good for people, and study after study has observed that populations who consume animal-rich diets experience poorer health outcomes.

3. Flexitarian diet & climate change impact

So we’ve established that a flexitarian diet may offer benefits in the reduction of food-related disease burden compared to current dietary patterns – but just how much more environmentally sustainable is the occasional inclusion of animal-based foods? Turns out – quite a lot. 

Research from Johns Hopkins University has recently concluded that a flexitarian diet (defined by them as one that is entirely plant-based 2 out of 3 meals each day) indeed offers more of a climate change mitigation potential than a vegetarian diet inclusive of dairy and eggs. [9] As you can see from the graph below, after a vegan diet, the most sustainable diet was identified to be the flexitarian diet. This is because dairy – which features prominently in most vegetarian diets – still depends on extremely resource-intensive cows. 

Some other interesting findings of their research: If the entire world ate a Western-style diet, global food-related emissions would grow by 135% – but if the entire world went vegan, 70% of food-related global emissions could be cut. [9]  The research also found that a vegan diet supplemented with “low-food chain animals” such as molluscs and insects could achieve a similar reduction in emissions while also providing a more balanced source of protein and micronutrients (although, obviously, good luck convincing the world to eat bugs). Not quite as impressive but still meaningful is the 41% potential reduction in food-related emissions if the world adopted a flexitarian dietary framework.  

These findings have been replicated elsewhere. Research by Springmann et al. concluded that only by adopting a flexitarian (with modest amounts of animal protein but limited red meat) or a vegan diet would climate change be limited to under two degrees. [10] In other words, global implementation of a flexitarian diet is necessary to ensure that we limit our planet’s warming to an acceptable level – although, of course, a vegan diet would be better. 

Bottom line? While more research is needed to assess the exact health benefits a flexitarian diet can confer, there is widespread consensus in the scientific community that a flexitarian diet implemented at a global level would have extremely important effects on mitigating climate change.

  1. Tips for implementing a best-practice flexitarian diet 

So – you’re interested in trying out a flexitarian diet or perhaps you’d like to encourage a family member or friend to give it a go. Where do you start – and what’s the best way to do this?

  1. Focus on a more abundant INCLUSION of plants rather than on the REDUCTION of animal-based foods. Make veggies, legumes, fruits and whole grains the stars of your meals, and you’ll find yourself naturally consuming less animal-based foods.
  2. If you’re eating animal foods each meal – try cutting down to only one meal a day. If you’re already eating less than that – try perhaps limiting your animal food consumption to once a week or for special occasions. Find whatever works for you. Long-term, you could aim for around 10-15% of your calories to be sourced from animal foods. 
  3. Take the transition slow to allow time for your gut microbiome to adapt to the increase in fibre that will naturally occur if you’re eating more plant-based foods. This will also give your palate time to adjust to all the new flavours you’ll be experiencing! 
  4. Learn about easy plant-based swaps: plant milk instead of cow’s milk, nutritional yeast instead of parmesan, soy or almond yogurts instead of dairy yogurt, TVP or tempeh to replace the mince in a sauce, and make scrambled eggs with tofu instead. 
  5. Learn how to make some kick-ass plant-based recipes so that you’re invigorated by the endless plant-based culinary opportunities – I have a few recipes here to get you going, but I love recipes from The Minimalist Baker and The Buddhist Chef too. 

Conclusion

As the ill effects of excessive meat consumption on health and the environment continue to surface, flexitarian diets offer a reasonable path for those who may not want to give meat up altogether to improve their health and reduce their environmental footprint. Flexitarianism is a digestible and easy-to-implement shift that affords a guilt-free approach to food consumption. Rather than dictating precisely what to eat and what not to eat, a flexitarian diet simply says: “eat more plants, and less animals”. It also allows for individuals to not be confined by a strict label: in this framework, there is no shame involved in indulging in the occasional slice of cheese pizza.  

As this article has discussed, while it’s hard to quantify just how much healthier a flexitarian diet is compared to the average omnivore diet – there is no question that it is healthier.  As I’ve said elsewhere before – a healthy diet is a spectrum, it isn’t all or nothing. 

But perhaps the strongest argument for a flexitarian diet is the sustainability implications it can afford: because of its approachable and easy-to-implement nature, the possibility of a global uptake of a flexitarian diet could prove to be instrumental in lowering global food-related emissions. 

Therefore, although a plant-based diet would obviously be optimal, ethics aside, I strongly support the uptake of a flexitarian diet for people who are looking to reduce their animal food consumption but aren’t quite happy with entirely removing all animal foods from their diets. The global, collective benefit we can achieve by inspiring people to reduce their consumption of animal foods is arguably stronger in the long term than trying (and failing) to get everyone to completely eliminate all animal foods.

References

[1] Bakker E de, de Bakker E, Dagevos H. Reducing Meat Consumption in Today’s Consumer Society: Questioning the Citizen-Consumer Gap. Journal of Agricultural and Environmental Ethics 2012;25:877–94. doi:10.1007/s10806-011-9345-z.

[2] One third of Americans consider themselves “flexitarian.” New York Post 2018. https://nypost.com/2018/10/26/one-third-of-americans-consider-themselves-flexitarian/ 

[3] Smithers R. Third of Britons have stopped or reduced eating meat – report. The Guardian 2018. http://www.theguardian.com/business/2018/nov/01/third-of-britons-have-stopped-or-reduced-meat-eating-vegan-vegetarian-report 

[4] Baines S, Powers J, Brown WJ. How does the health and well-being of young Australian vegetarian and semi-vegetarian women compare with non-vegetarians? Public Health Nutr 2007;10:436–42.

[5] Tantamango-Bartley Y, Jaceldo-Siegl K, Fan J, Fraser G. Vegetarian Diets and the Incidence of Cancer in a Low-risk Population. Cancer Epidemiology Biomarkers & Prevention 2013;22:286–94. doi:10.1158/1055-9965.epi-12-1060.

[6] Orlich MJ, Singh PN, Sabaté J, Jaceldo-Siegl K, Fan MJ, Knutsen S, et al. Vegetarian Dietary Patterns and Mortality in Adventist Health Study 2. JAMA Intern Med 2013;173:1230.

[7] Tonstad S E al. Vegetarian diets and incidence of diabetes in the Adventist Health Study-2. – PubMed – NCBI n.d. https://www.ncbi.nlm.nih.gov/pubmed/21983060 (accessed October 10, 2019).

[8] Chen C, Chaudhary A, Mathys A. Dietary Change Scenarios and Implications for Environmental, Nutrition, Human Health and Economic Dimensions of Food Sustainability. Nutrients 2019;11. doi:10.3390/nu11040856.

[9] Center for a Livable Future. Center for a Livable Future n.d. https://clf.jhsph.edu/ 

[10] https://www.thelancet.com/journals/lanplh/article/PIIS2542-5196(18)30206-7/fulltext 

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