short-term vegetarianism

A healthy, nutritious diet is essential for your physical and mental well-being. 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.

Individuals who follow a mostly animal-based diet (omnivores), and want to move towards a more plant-based diet, may be wondering what the short-term benefits of adopting a vegetarian diet for a day, a week, or a month are.

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

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 Short-Term Vegetarianism

We have looked at numerous studies that have reported the many health benefits of following a vegetarian diet for a short period of time.

The length of time participants in these studies followed a vegetarian diet varied from 4 days to 16 weeks.

In the sections that follow we highlight studies that have linked short-term vegetarianism with health benefits such as:

  • Lowered blood pressure
  • Weight loss
  • Improved heart health
  • Improved gut health
  • Improved bowel habits and lowered stress levels
  • Reduced chronic medication usage
  • Reduced exposure to environmental chemicals

Lowered Blood Pressure

A short-term vegetarian diet may lower your blood pressure.

A study published in the American Journal of Lifestyle Medicine, reported that participants following a 15-day whole-food, plant-based diet rich in vegetables, fruits, and whole grains had a significant reduction in systolic blood pressure “average systolic blood pressure drop was 6.8 points (16.8 points for those with systolic blood pressure >140)” (Friedman et al., 2021).

A study conducted by researchers from the Texas Woman’s University, evaluated the effectiveness of a 4-week raw, plant-based diet consisting of raw fruits, vegetables, seeds, and avocado on hypertension and hypercholesterolemia. Significant reductions in the systolic and diastolic measurements were observed after the 4-week period “Four weeks of a defined, plant-based dietary intervention resulted in clinically significant reductions in systolic blood pressure, diastolic blood pressure, blood pressure medication usage, total medication usage, and serum lipids” (Najjar et al., 2018).

Weight Loss and Improved Heart Health

A short-term vegetarian diet may provide a beneficial impact on your cardiovascular health and weight loss. Cardiometabolic risk factors include: obesity, hypertension, low-density lipoprotein (LDL) cholesterol, and insulin resistance.

A study published in the Journal of the American Nutrition Association, investigated the impact of adopting a vegan or Mediterranean diet for 16 weeks on health parameters such as body weight, and cardiometabolic risk factors. They found that switching to a vegan or Mediterranean diet for a 16-week period improved all health parameters “A low-fat vegan diet improved body weight, lipid concentrations, and insulin sensitivity, both from baseline and compared with a Mediterranean diet. Blood pressure decreased on both diets, more on the Mediterranean diet” (Barnard et al., 2020).

A study published in the journal, Nutrition, investigated the effect of a 12-week whole-food, plant-based diet on cardiovascular health of individuals from Montreal, Canada who had at least one risk factor of cardiovascular disease. A positive improvement in cardiovascular risk parameters such as weight, total cholesterol, and low-density lipoprotein was observed after the 12-week period “The whole-food, plant-based nutrition program improves cardiovascular health in adults” (Morin et al., 2019).

Scientists from the University of Rochester, who conducted an 8-week whole-food, plant-based lifestyle modification program on members of the community reported an improvement in body weight towards a healthier body mass index (BMI), and reduced cholesterol levels “A whole-food plant-based dietary intervention may provide significant short-term benefits for both non-vegetarian, vegetarian, and vegan individuals; participants experienced statistically significant weight loss and reductions in total and LDL cholesterol” (Campbell et al., 2019).

Scientists from the University of Oslo, investigated the effect of a 3-week vegetarian diet and fasting on patients with fibromyalgia. A 3-week vegetarian diet lead to decreased levels of peroxide and plasma fibrinogen levels - high levels of these compounds is linked with heart attack, stroke, and preeclampsia “The results suggest that vegetarian diet/fasting may have a beneficial influence on the concentration of serum peroxides and plasma fibrinogen concentration” (Høstmark et al., 1993).

Improved Gut Health

A short-term vegetarian diet may positively impact your gut health, by providing your gut with an abundance of “good” microbes that produce health promoting compounds, after as little as 4 days.

A study conducted by scientists from the Department of Nutrition at the University of California reported that switching from a fast food diet (high in saturated fats and refined carbohydrates) to a Mediterranean diet (rich in whole grains, fruits, vegetables, and nuts) had a positive impact on gut microbiome composition after just 4 days “Mediterranean diet altered human gut microbiome composition and its metabolites after just 4 days” (Zhu et al., 2020). Participants who followed a Mediterranean diet had more health promoting compounds in their gut “bacterially produced metabolites indole-3-lactic acid and indole-3-propionic acid, which have been shown to confer beneficial effects on neuronal cells, increased after the Mediterranean diet and decreased after the fast food diet”.

A study published in the journal, Gut, investigated the effect of an 8-week Mediterranean diet on gut health of participants who usually consumed a low intake of fruit and vegetables, and lead sedentary lifestyles. The results indicated that after the 8-week dietary intervention, participants had a positive improvement in gut health with an increase in diversity and gene richness “Switching subjects to a Mediterranean diet while maintaining their energy intake reduced their blood cholesterol and caused multiple changes in their microbiome and metabolome” (Meslier, 2020).

Reduced Chronic Medication

Short-term vegetarianism may lead to a reduction in chronic medication usage.

Scientists from the University of Rochester, who conducted an 8-week whole-food, plant-based lifestyle modification program on members of the community reported that over a quarter of participants were able to reduce or stop their chronic medication after the 8-week period “Twenty-one (26.9%) participants were able to decrease or stop at least one chronic medication” (Campbell et al., 2019).

A study published in the journal, Clinical Cardiology, reported a reduction in total medication usage after patients adhered to a 4-week raw plant-based diet “A defined plant-based diet can be used as an effective therapeutic approach in the clinical setting in the treatment of hypertension, hypercholesterolemia, and other cardiovascular risk factors while simultaneously reducing overall medication usage” (Najjar et al., 2018).

Improved Bowel Habits and Reduced Stress

Short-term vegetarianism can improve your bowel habits, and reduce stress.

A study published in the journal, Clinical Nutrition Research, evaluated the effectiveness of a 12-week vegetarian diet on stress status and bowel habits in middle school students and teachers. At the end of the 12-week period, the stress levels of the teachers had significantly reduced, and frequency of constipation decreased for both teachers and students “The results of this study confirmed that providing vegetables-focused meal in school improved nutrition status, bowel conditions in students and teachers and reduced the stress levels in teachers” (Lee et al., 2016).

Reduced Symptoms of Osteoarthritis

Short-term vegetarianism may reduce the symptoms of osteoarthritis. Osteoarthritis is one of the most common types of arthritis, and is characterised by degradation of cartilage and bone in joints.

A study conducted by scientists from the Department of Internal Medicine at Michigan University, investigated the effectiveness of a 6-week whole-food, plant-based diet (WFPB) on alleviating symptoms of osteoarthritis “WFPB diet was associated with a significant reduction in pain compared to an ordinary omnivorous diet, with statistically significant pain reduction seen as early as two weeks after initiation of the dietary modification” (Clinton et al., 2015).

6-week Raw Vegan Diet Rapidly Reverses Lupus Nephritis

A study published in the Journal of Disease Reversal and Prevention, investigated the effect of a 6-week raw, whole-food, plant-based diet on patients suffering from symptoms brought on by the autoimmune disease, lupus. After the 6-week diet, a positive improvement in kidney function, energy and joint pain levels was noted, with a 24-year old female no longer requiring a kidney transplant or dialysis “it was determined that she no longer needed dialysis or a kidney transplant. Her energy and joint pain levels also significantly improved” (Goldner, 2019).

Reduced Environmental Chemical Exposure (Antibiotics and Phthalates)

Adhering to a short-term vegetarian diet may lead to reduced levels of environmental chemical exposure to your body.

A study published in the journal, Environmental Research evaluated the influence of a short-term, 5-day vegetarian diet on the amount of environmental chemicals such as antibiotics and phthalates (chemicals used in plastic manufacturing) in the participants urine, they reported that following a vegetarian diet for 5 days lead to a decrease of antibiotics and phthalates in the body “even short-term changes in dietary behaviour may significantly decrease inadvertent exposure to antibiotics and phthalates and hence may reduce oxidative stress levels” (Ji et al., 2010).

Drawbacks of Short-Term Vegetarianism

In the previous sections we have looked at the many health benefits of a short-term vegetarian diet. In the section that follows we will discuss the potential drawbacks of short-term vegetarianism.

Although short-term vegetarianism (rich in whole grains, fruits and vegetables) is linked to positive health outcomes like improved cardiovascular health, improved gut health, weight loss, reduced blood pressure, improved bowel habits, and reduced stress levels; switching back to an omnivorous diet, rich in animal products and refined carbohydrates, could reverse the positive health effects obtained from a vegetarian diet.

Therefore, it is advised to work towards a sustainable long-term vegetarian diet in order to reap the short-term, and long-term health benefits a vegetarian diet can provide.

Wrapping Up

As studies have shown, short-term vegetarianism is capable of positively influencing your health in just a few days.  


Following a plant-based diet, even for a short period of time has numerous benefits to your health including:

  • Lowered blood pressure
  • Weight loss
  • Improved heart health
  • Improved gut health
  • Improved bowel habits and reduced stress levels

A well-planned, balanced and varied vegetarian diet rich in healthful plant-based foods such as whole grains, legumes, fruits, vegetables, nuts and seeds can provide your body with the nutrition it needs to maintain optimal physical and mental health.


If a short-term vegetarian diet can provide our bodies with such positive health changes in such a short period of time, imagine what a long-term vegetarian diet could do for your health and longevity.

References:

  • Barnard, N. D., Alwarith, J., Rembert, E., Brandon, L., Nguyen, M., Goergen, A., ... & Kahleova, H. (2020). A Mediterranean diet and low-fat vegan diet to improve body weight and cardiometabolic risk factors: a randomized, cross-over trial. Journal of the American College of Nutrition, 1-13.
  • Campbell, E. K., Fidahusain, M., & Campbell Ii, T. M. (2019). Evaluation of an eight-week whole-food plant-based lifestyle modification program. Nutrients, 11(9), 2068.
  • Clinton, C. M., O'Brien, S., Law, J., Renier, C. M., & Wendt, M. R. (2015). Whole-foods, plant-based diet alleviates the symptoms of osteoarthritis. Arthritis, 2015.
  • Friedman, S. M., Barnett, C. H., Franki, R., Pollock, B., Garver, B., & Barnett, T. D. (2021). Jumpstarting Health With a 15-Day Whole-Food Plant-Based Program. American Journal of Lifestyle Medicine, 15598276211006349.
  • Goldner, B. (2019). Six week raw vegan nutrition protocol rapidly reverses lupus nephritis: a case series. International Journal of Disease Reversal and Prevention, 1(1).
  • Høstmark, A. T., Lystad, E., Vellar, O. D., Hovi, K., & Berg, J. E. (1993). Reduced plasma fibrinogen, serum peroxides, lipids, and apolipoproteins after a 3-week vegetarian diet. Plant Foods for Human Nutrition, 43(1), 55-61.
  • Ji, K., Kho, Y. L., Park, Y., & Choi, K. (2010). Influence of a five-day vegetarian diet on urinary levels of antibiotics and phthalate metabolites: a pilot study with “Temple Stay” participants. Environmental research, 110(4), 375-382.
  • Lee, B. R., Ko, Y. M., Cho, M. H., Yoon, Y. R., Kye, S. H., & Park, Y. K. (2016). Effects of 12-week vegetarian diet on the nutritional status, stress status and bowel habits in middle school students and teachers. Clinical nutrition research, 5(2), 102-111.
  • Meslier, V., Laiola, M., Roager, H. M., De Filippis, F., Roume, H., Quinquis, B., ... & Ercolini, D. (2020). Mediterranean diet intervention in overweight and obese subjects lowers plasma cholesterol and causes changes in the gut microbiome and metabolome independently of energy intake. Gut, 69(7), 1258-1268.
  • Morin, É., Michaud-Létourneau, I., Couturier, Y., & Roy, M. (2019). A whole-food, plant-based nutrition program: Evaluation of cardiovascular outcomes and exploration of food choices determinants. Nutrition, 66, 54-61.
  • Najjar, R. S., Moore, C. E., & Montgomery, B. D. (2018). A defined, plant‐based diet utilized in an outpatient cardiovascular clinic effectively treats hypercholesterolemia and hypertension and reduces medications. Clinical cardiology, 41(3), 307-313.
  • Zhu, C., Sawrey-Kubicek, L., Beals, E., Rhodes, C. H., Houts, H. E., Sacchi, R., & Zivkovic, A. M. (2020). Human gut microbiome composition and tryptophan metabolites were changed differently by fast food and Mediterranean diet in 4 days: a pilot study. Nutrition Research, 77, 62-72.

Short-Term Vegetarian Studies

Benefits of Short-term Vegetarianism

Date

Name of Paper

Journal Name

Link to Paper

2021

Five-Month Trial of Whole-Food Plant-Based Diet in a Patient With Coexisting Myasthenia Gravis and Lambert-Eaton Myasthenic Syndrome

American Journal of Lifestyle Medicine

2021

Jumpstarting Health With a 15-Day Whole-Food Plant-Based Program

American Journal of Lifestyle Medicine

2021

Implementation of a Plant-Based, Nutrition Program in a Large Integrated Health Care System: Results of a Pilot Program

Journal of Primary Care and Community Health

2021

The Impact of Diet on Urinary Risk Factors for Cystine Stone Formation

Nutrients

2021

A Mediterranean Diet and Low-Fat Vegan Diet to Improve Body Weight and Cardiometabolic Risk Factors: A Randomized, Cross-over Trial

Journal of the American College of Nutrition

2020

Human gut microbiome composition and tryptophan metabolites were changed differently by fast food and Mediterranean diet in 4 days: a pilot study

Nutrition Research

2020

Changes in biochemical parameters by gender and time: Effect of short-term vegan diet adherence

PloS One

2020

Dietary Intakes and Cardiovascular Health of Healthy Adults in Short-, Medium-, and Long-Term Whole-Food Plant-Based Lifestyle Program

Nutrients

2020

Mediterranean diet intervention in overweight and obese subjects lowers plasma cholesterol and causes changes in the gut microbiome and metabolome independently of energy intake

Gut

2019

Evaluation of an Eight-Week Whole-Food Plant-Based Lifestyle Modification Program

Nutrients

2019

A whole-food, plant-based nutrition program: Evaluation of cardiovascular outcomes and exploration of food choices determinants

Nutrition

2019

Six Week Raw Vegan Nutrition Protocol Rapidly Reverses Lupus Nephritis: A Case Series

International Journal of Disease Reversal and Prevention

2018

Impact of a 3-Months Vegetarian Diet on the Gut Microbiota and Immune Repertoire

Frontiers in Immunology

2018

Consumption of a defined, plant-based diet reduces lipoprotein(a), inflammation, and other atherogenic lipoproteins and particles within 4 weeks

Clinical Cardiology

2018

A defined, plant-based diet utilized in an outpatient cardiovascular clinic effectively treats hypercholesterolemia and hypertension and reduces medications

Clinical Cardiology

2017

The BROAD study: A randomised controlled trial using a whole food plant-based diet in the community for obesity, ischaemic heart disease or diabetes

Nutrition and Diabetes

2017

Effects of an Ad Libitum Consumed Low-Fat Plant-Based Diet Supplemented with Plant-Based Meal Replacements on Body Composition Indices

BioMed Research International

2017

A Plant-Based Nutrition Program

American Journal of Nursing

2016

[SHORT TERM EFFECTS ON LIPID PROFILE AND GLYCAEMIA OF A LOW-FAT VEGETARIAN DIET]

Nutricion Hospitalaria

2016

Effects of 12-week Vegetarian Diet on the Nutritional Status, Stress Status and Bowel Habits in Middle School Students and Teachers

Clinical Nutrition Research

2015

Whole-foods, plant-based diets alleviates the symptoms of osteoarthritis

Arthritis

2015

Randomization to plant-based dietary approaches leads to larger short-term improvements in Dietary Inflammatory Index scores and macronutrient intake compared with diets that contain meat

Nutrition Research

2014

Effects of 7 days on an ad libitum low-fat vegan diet: the McDougall Program cohort

Nutrition Journal

2013

A multicenter randomized controlled trial of a plant-based nutrition program to reduce body weight and cardiovascular risk in the corporate setting: the GEICO study

European Journal of Clinical Nutrition

2010

Influence of a five-day vegetarian diet on urinary levels of antibiotics and phthalate metabolites: A pilot study with “Temple Stay” participants

Environmental Research

2006

Effect of a short-term diet and exercise intervention on inflammatory/anti-inflammatory properties of HDL in overweight/obese men with cardiovascular risk factors

Journal of Applied Physiology

2005

The effects of a low-fat, plant-based dietary intervention on body weight, metabolism, and insulin sensitivity

The American Journal of Medicine

1993

Reduced plasma fibrinogen, serum peroxides, lipids, and apolipoproteins after a 3-week vegetarian diet

Plant Foods for Human Nutrition

1991

Controlled trial of fasting and one-year vegetarian diet in rheumatoid arthritis

The Lancet

1983

BLOOD-PRESSURE-LOWERING EFFECT OF A VEGETARIAN DIET: CONTROLLED TRIAL IN NORMOTENSIVE SUBJECTS

The Lancet

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