Flexitarianism, also known as semi-vegetarianism, is a vegetarian dietary style that focuses predominantly on consumption of plant-based foods, while allowing the occasional consumption of meat and animal-origin products (fish, poultry, and dairy).

Flexitarianism is gaining in popularity worldwide, mostly for its purported health benefits, environmental benefits, and animal welfare benefits.

Studies have shown that high intakes of red meat, and processed meat products have been linked to cardiovascular disease, obesity, and cancers (Pan et al., 2012; Song et al., 2016).

According to research by Derbyshire (2017) “Flexitarian diets may have emerging health benefits in relation to weight loss, metabolic health, and diabetes prevention”.

Long-term adherence to a vegetarian diet has shown to provide a myriad of positive health benefits, such as reduced risk of cardiovascular disease, cancer, diabetes, hypertension, obesity, and reduced mental health disorders.

Society is becoming increasingly more aware of the detrimental impact our dietary habits – meat in particular – have on the environment. With livestock production being a main contributor of greenhouse gas emissions, land and water degradation.

You may be familiar with the phrase “Meatless Monday”, a campaign designed to encourage consumers to reduce their meat intake, for as-little-as one day/meal a week, with the aim of mitigating climate change and encouraging healthy eating habits in the general population.

Flexitarian diets may be a good transitory diet for individuals looking to follow a healthier plant-based diet, that is not as restrictive.

In this article we explain (in plain English!) the conclusions of scientific studies that have looked at flexitarianism. 

Vegetarian diets consist of plant-based foods rich in whole grains, legumes, nuts, seeds, fruits, and vegetables, while avoiding red meat, processed meat products, refined foods, and sweets.

There are several variations of a vegetarian diet:

  • Lacto-vegetarians allow the consumption of low-fat dairy products
  • Ovo-vegetarians allow the consumption of eggs
  • Pescatarians allow the consumption of fish
  • Pollotarians allow lean white meat such as chicken to be consumed.

Benefits of Flexitarianism

In the sections that follow we highlight studies that have linked flexitarianism with health benefits such as:

  • Weight loss
  • Reduced risk of diabetes
  • Improved heart health
  • Reduced risk of all-cause mortality

Weight Loss

Flexitarianism may aid in weight loss and weight control.

A study published in the British Journal of Nutrition, evaluated the effectiveness of various styles of vegetarianism (including flexitarianism, and pescatarianism) and their impact on body weight.

They reported that compared to omnivores, all vegetarian dietary styles resulted in reduced body mass index “All dietary profiles had a lower body mass index (BMI) compared with the omnivores” (Wozniak et al., 2020).

A study published in the journal, Clinical Nutrition Research, investigated the impact of a long-term (20 years) semi-vegetarian diet on body weight parameters of a group of Korean postmenopausal women.

They reported that semi-vegetarianism resulted in reduced body weight compared to non-vegetarians “Compared with the middle-aged women who followed a non-vegetarian diet, the weight, body mass index (BMI), and body fat percentage of those who followed a vegetarian diet were significantly lower” (Kim & Bae, 2015).

Reduced Risk of Diabetes

Flexitarianism may reduce your risk of developing diabetes.

A study conducted by researchers from the Department of Food and Nutrition at the Korea National University of Transportation, investigated the influence of long-term semi-vegetarian diets on insulin resistance levels in postmenopausal women.

Their findings showed that long-term adherence to a semi-vegetarian diet was associated with improved insulin resistance and glucose metabolism, both of which are risk factors for diabetes “The results of this study support the beneficial effect of a long-term semi-vegetarian diet specifically, that it can improve the insulin resistance and glucose metabolism in postmenopausal women” (Kim & Bae, 2015).

Researchers, Agrawal et al. (2014) investigated the risk of diabetes among individuals following a vegetarian diet. They found that compared to omnivores, those following a vegetarian, including semi-vegetarian dietary pattern were at less risk of developing diabetes “semi-vegetarian diets were associated with a lower likelihood of diabetes”.

Improved Heart Health

Flexitarianism may provide protective benefits for your heart.

A study published in the British Journal of Nutrition, evaluated the effectiveness of various styles of vegetarianism (including Flexitarianism, and pescatarianism) and their impact on cardiovascular health in a Swiss population.

Researchers made use of data from the Swiss Bus Santé study, a cross-sectional population-based study that has gathered data annually since 1993.  Their findings suggest that vegetarian diets, including flexitarianism, provide protective benefits to cardiovascular health “Compared with omnivores, individuals with reduced meat intake generally showed a more favourable profile in terms of cardiovascular risk factors” (Wozniak et al., 2020).

Cardiovascular risk factors include hypertension, high cholesterol, and obesity.

In this study, flexitarians were found to have lower total cholesterol and LDL (bad cholesterol) compared to omnivores “flexitarians had lower values of total cholesterol and LDL”.

Flexitarians were also reported to have reduced blood pressure and were less prone to develop hypertension “Flexitarians and vegetarians had lower rates of hypertension, and all three diets had lower values of blood pressure compared with omnivores” (Wozniak et al., 2020).

Protective Against Inflammatory Bowel Disease Relapse

Inflammatory Bowel Disease, is a medical condition characterised by chronic inflammation of the intestines.

Inflammatory Bowel Disease includes Crohn’s disease and ulcerative colitis.

Flexitarianism may be an effective diet offering protective benefits against inflammatory bowel disease (IBD) relapse.

A study published in the World Journal of Gastroenterology, evaluated the effectiveness of a semi-vegetarian diet on preventing Crohn’s disease relapse in patients who had reached remission. A 2-year clinical trial was performed, with patients in remission from Crohn’s disease instructed to follow a semi-vegetarian diet.

Findings from this study indicate that patients in remission from Crohn’s disease may benefit from a semi-vegetarian diet to avoid a relapse of inflammatory symptoms “a semi-vegetarian diet was highly effective in preventing relapse in Crohn’s disease” (Chiba et al., 2010).

Further research conducted by the same authors, analysed the impact of a high fibre, semi-vegetarian diet on gut inflammation in patients suffering from inflammatory bowel disease.

They found a positive link between a high fibre diet and gut inflammation “We believe a plant-based diet not only is effective for gut inflammation but also promotes the general health of IBD patients” (Chiba et al., 2015).

Reduced Risk of All-Cause Mortality

Flexitarianism may lower your risk of all-cause mortality.

Reduced red meat consumption has been linked to better health outcomes.

Scientists from the Department of Nutrition and Epidemiology, at the Harvard School of Public Health, investigated the influence of diet on all-cause mortality.

Their findings indicate that individuals who reduced their red meat intake and opted for healthier protein alternatives were at less risk of dying from cardiovascular disease, and cancer “Red meat consumption is associated with an increased risk of total, cardiovascular disease, and cancer mortality. Substitution of other healthy protein sources for red meat is associated with a lower mortality risk” (Pan et al., 2012).

Pan et al. (2012) also reported that replacing one serving of red meat for one serving of fish, whole grains, legumes or nuts could reduce your risk of death by 7% to 19% “substitutions of 1 serving per day of other foods (including fish, poultry, nuts, legumes, low-fat dairy, and whole grains) for 1 serving per day of red meat were associated with a 7% to 19% lower mortality risk”.

In another study, scientists from the Loma Linda University, California, investigated the relationship between various vegetarian dietary styles and mortality in the Adventist Health Study 2.

They reported that vegetarian diets, including semi-vegetarian diets are linked to reduced chances of dying from disease “vegetarian diets, or similar diets with reduced meat consumption, may be associated with a lower risk of death” (Orlich et al., 2013).

Another study conducted by scientists from the Department of Public Health, at University of Oxford, analysed various dietary scenarios and their impact on human health and climate change.

They reported that halving your dietary meat and dairy intake and substituting with fruit, vegetables and cereals would lead to over 36 000 less deaths in the UK alone “50% reduction in meat and dairy replaced by fruit, vegetables and cereals: resulted in 36 910 deaths delayed or averted per year” (Scarborough et al., 2012).

Environmental Benefits

Flexitarianism may provide environmental benefits.

Climate change is one of the biggest challenges our planet is facing in the modern-era.

The negative effect meat consumption has on our environment is becoming increasingly more apparent “the livestock sector has been shown to be the largest single contributor for greenhouse gas emissions globally” (Raphaely & Marinova, 2014).

A study published in the journal, Renewable Energy, evaluated the effectiveness of a flexitarian, reduced meat diet on mitigating climate change.

Their findings suggest that a shift towards a reduced meat diet would offer benefits to human health and planetary health, by reducing greenhouse gas emissions associated with livestock production “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).

According to a study conducted by researchers from the European Commission, Joint Research Institute in Spain, switching to a flexitarian diet would cut greenhouse gas emissions, specifically ammonia emissions by a third “a shift to plant-based (flexitarian) diets would reduce ammonia emissions by 33% in the European Union (EU), generating significant co-benefits for air quality and human health” (Himics & Perez-Dominguez, 2022).

Drawbacks of Flexitarianism

In the previous sections we have looked at the many health benefits of a flexitarianism diet. In the section that follows we will discuss the potential drawbacks of flexitarianism.

As flexitarian diets are less restrictive, and allow the consumption of meat, nutritional deficiencies such as vitamin B12 are less common.

Although flexitarianism, when compared to non-vegetarian diets, has been linked to positive health outcomes like improved cardiovascular health, weight loss, reduced risk of diabetes, and all-cause mortality; evidence suggests that vegetarian and vegan diets provide greater benefit to health outcomes than a flexitarian diet.

When analysing the scientific evidence in the previous section, the positive benefits were always greater in those following a vegetarian or vegan diet, than a semi-vegetarian diet.

This may be due to the fact that diets containing meat have been linked to cardiovascular disease, obesity, and cancers (Pan et al., 2012; Song et al., 2016), which could negate the positive health benefits of a plant-based diet.

When following a flexitarian diet, it is important to ensure that you are consuming a variety of healthful plant-based foods, avoiding refined, processed foods, and limiting your meat intake where possible.

Wrapping Up

Evidence suggests that a semi-vegetarian diet is capable of positively influencing your health.

Reducing your red meat intake, even for one serving a day, and consuming more healthful plant-based foods has shown to have a positive impact on human health and the health of the planet.


The numerous benefits linked to a flexitarian diet include:

  • Weight loss
  • Reduced risk of diabetes
  • Improved heart health
  • Reduced risk of all-cause mortality
  • Environmental benefits

A well-planned, balanced and varied flexitarian diet rich in healthful plant-based foods such as whole grains, legumes, fruits, vegetables, nuts and seeds, and with the occasional consumption of meat, can provide your body with the nutrition it needs to grow and stay healthy.


Flexitarian diets could be a good transitory diet for individuals looking to follow a healthier lifestyle, that is not as restrictive.


As men are more reluctant to stop eating meat, a flexitarian diet may offer them a way to increase their plant-based dietary habits while still including their meat preferences (Derbyshire, 2017).


Finally, it is advised to always consult with your doctor or dietitian before starting a new diet.

References:

  • Agrawal, S., Millett, C. J., Dhillon, P. K., Subramanian, S. V., & Ebrahim, S. (2014). Type of vegetarian diet, obesity and diabetes in adult Indian population. Nutrition journal, 13(1), 1-18.
  • Chiba, M., Abe, T., Tsuda, H., Sugawara, T., Tsuda, S., Tozawa, H., ... & Imai, H. (2010). Lifestyle-related disease in Crohn’s disease: relapse prevention by a semi-vegetarian diet. World journal of gastroenterology: WJG, 16(20), 2484.
  • Chiba, M., Tsuji, T., Nakane, K., & Komatsu, M. (2015). High amount of dietary fiber not harmful but favorable for Crohn disease. The Permanente Journal, 19(1), 58.
  • Derbyshire, E. J. (2017). Flexitarian diets and health: a review of the evidence-based literature. Frontiers in nutrition, 3, 55.
  • Himics, M., Giannakis, E., Kushta, J., Hristov, J., Sahoo, A., & Perez-Dominguez, I. (2022). Co-benefits of a flexitarian diet for air quality and human health in Europe. Ecological Economics, 191, 107232.
  • Kim, M. H., & Bae, Y. J. (2015). Comparative study of serum leptin and insulin resistance levels between Korean postmenopausal vegetarian and non-vegetarian women. Clinical nutrition research, 4(3), 175-181.
  • Orlich, M. J., Singh, P. N., Sabaté, J., Jaceldo-Siegl, K., Fan, J., Knutsen, S., ... & Fraser, G. E. (2013). Vegetarian dietary patterns and mortality in Adventist Health Study 2. JAMA internal medicine, 173(13), 1230-1238.
  • Pan, A., Sun, Q., Bernstein, A. M., Schulze, M. B., Manson, J. E., Stampfer, M. J., ... & Hu, F. B. (2012). Red meat consumption and mortality: results from 2 prospective cohort studies. Archives of internal medicine, 172(7), 555-563.
  • Raphaely, T., & Marinova, D. (2014). Flexitarianism: Decarbonising through flexible vegetarianism. Renewable Energy, 67, 90-96.
  • Scarborough, P., Allender, S., Clarke, D., Wickramasinghe, K., & Rayner, M. (2012). Modelling the health impact of environmentally sustainable dietary scenarios in the UK. European journal of clinical nutrition, 66(6), 710-715.
  • Song, M., Fung, T. T., Hu, F. B., Willett, W. C., Longo, V. D., Chan, A. T., & Giovannucci, E. L. (2016). Association of animal and plant protein intake with all-cause and cause-specific mortality. JAMA internal medicine, 176(10), 1453-1463.
  • Wozniak, H., Larpin, C., de Mestral, C., Guessous, I., Reny, J. L., & Stringhini, S. (2020). Vegetarian, pescatarian and flexitarian diets: sociodemographic determinants and association with cardiovascular risk factors in a Swiss urban population. British Journal of Nutrition, 124(8), 844-852.

Flexitarianism Studies

Date

Name of Paper

Journal Name

Link to Paper

2022

Co-benefits of a flexitarian diet for air quality and human health in Europe

Ecological Economics

2021

Vitamin B6 Status among Vegetarians: Findings from a Population-Based Survey

Nutrients

2020

Vegetarian, pescatarian and flexitarian diets: sociodemographic determinants and association with cardiovascular risk factors in a Swiss urban population

British Journal of Nutrition

2018

Health and nutritional aspects of sustainable diet strategies and their association with environmental impacts: a global modelling analysis with country-level detail

The Lancet Planetary Health

2018

Global Provisioning of Red Meat for Flexitarian Diets

Frontiers in Nutrition

2017

Flexitarian Diets and Health: A Review of the Evidence-Based Literature

Frontiers in Nutrition

2016

Analysis and valuation of the health and climate change cobenefits of dietary change

Proceedings of the National Academy of Sciences

2014

Flexitarianism: Decarbonising through flexible vegetarianism

Renewable Energy

2014

Flexitarianism: a more moral dietary option

International Journal of Sustainable Society

2014

“Meatless days” or “less but better”? Exploring strategies to adapt Western meat consumption to health and sustainability challenges

Appetite

2013

Flexitarianism (Flexible or Part-Time Vegetarianism): A User-Based Dietary Choice for Improved Wellbeing

International Journal of User-driven Healthcare

2013

Systematic review of reducing population meat consumption to reduce greenhouse gas emissions and obtain health benefits: effectiveness and models assessments

International Journal of Public Health

2013

Nutrient Profiles of Vegetarian and Nonvegetarian Dietary Patterns

Journal of the Academy of Nutrition and Dietetics

2012

Modelling the health impact of environmentally sustainable dietary scenarios in the UK

European Journal of Clinical Nutrition

2012

Impact of a reduced red and processed meat dietary pattern on disease risks and greenhouse gas emissions in the UK: a modelling study

BMJ

2012

Red Meat Consumption and MortalityResults From 2 Prospective Cohort Studies

Arch Intern Med.

2009

Climate benefits of changing diet

Climatic Change

2009

Reducing Meat Consumption Has Multiple Benefits for the World's Health

Arch Intern Med.

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