What Happens To Your Body When You Eat Vegetarian During The Week

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If you're considering becoming flexitarian, or eating a meat-free diet at least part of the time, there's good news: it seems to have health benefits. A study in Nutrients in 2014, for instance, found that in comparison to fully omnivorous people, semi-vegetarian people appeared to have a more nutritious diet. If you stick to a meat-free diet during the week and only eat meat over the weekends, for example, you may see some significant changes in your health — but experts tell Bustle that your body's reaction depends very much on how you replace meat during the week, and that it's difficult to predict with 100% accuracy how flexitarianism will affect you.

Whether you're going flexitarian because of health concerns, worries about the impact of meat consumption on the planet, or other reasons, experts say the Mediterranean diet provides a good blueprint to follow. "In general, a diet that is rich in vegetables and sources of healthy oils like nuts and avocados is the best choice," Dr. Nate Favini M.D., the medical lead at virtual primary care organization Forward, tells Bustle. "When it comes to proteins, there are plenty of healthy vegetarian options like beans and tofu." On omnivorous weekends, he suggests fish with lots of omega-4 fatty acids, like salmon. Over time, these changes may cause significant shifts in your body and health.

Here's what eating vegetarian during the week might do to your body.

1. Your Reaction Will Depend On How You Replace Meat

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The health impact of weekday vegetarianism depends on how you replace meat on those five days, experts tell Bustle. "It really matters what specific foods you’re eating; if you’re trading out healthy fish for peanut butter and jelly sandwiches, your health is going to get worse," Favini tells Bustle. "But if you’re swapping red meat for greens, nuts, and avocados, your health is going to improve dramatically."

To make the transition into vegetarianism five days a week, Dawn Jackson Blatner, RDN, a registered dietitian and author of The Flexitarian Diet, tells Bustle that it's important to plan. "The biggest mistake people make is just cutting out meat," she says. "You really need to think of it as a protein swap. For every one ounce of meat, swap in a quarter of a cup of plant protein, such as beans or lentils."

She also recommends taking things slowly. If you're not ready to go vegetarian for a full five days, take it slow, decrease your meat portions, and try at least one new vegetarian recipe a week. "In a year you’ll have tried over 50 new things, and some of those are going be keepers that stay in your rotation," she tells Bustle.

2. You May Reduce Oxidative Stress On Your Body

"Going meat-free during the week or only eating meat on the weekends will definitely increase your plant food intake, which is an all-around good thing," nutritional consultant Stephanie Papadakis, founder of Gut of Integrity, tells Bustle. "Eating more plants, especially cruciferous veggies, which are high in antioxidants, helps reduce oxidative stress."

Oxidative stress is a process that damages the body's cells, and is slowed by antioxidants. It has been found to play a role in diseases we often get as we age, like neurodegenerative illnesses, cardiovascular problems, and liver issues. Studies have found that vegetarians tend to have lower levels of oxidative stress overall.

3. Your Heart Will Likely Thank You

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Being a vegetarian during the week may make your heart happy. Research done by the American Heart Association in 2015, using data from the European Prospective Investigation into Cancer and Nutrition (EPIC) of over 450,000 Europeans, found that cutting down on your meat consumption and going semi-vegetarian may cut your risk of stroke and heart disease by up to 20%. An overview of flexitarianism published in Frontiers in Nutrition in 2016 also found that benefits included better metabolic health and lower blood pressure.

"A plant-based diet has a number of benefits, including a reduction in risk of death from ischemic heart disease — a restriction in blood supply to tissues, causing a shortage of oxygen," Dr. Mahmoud Ghannoum Ph.D., director of the Center for Medical Mycology at Case Western Reserve University and author of Total Gut Balance, tells Bustle.

Part of this benefit, says Favini, is likely due to the fact that flexitarians are eating lower amounts of red meat. "In general, red meat increases the risk of heart disease and should be avoided or eaten as a rare treat," he tells Bustle. New research has indicated that the link between heart disease and red meat may have been overstated, but it's still worth considering making it a smaller part of your diet.

4. You'll Reduce Inflammation

Inflammation is the body's normal reaction to invasive pathogeons like viruses, but it can also be sparked by lifestyle factors, like stress or particular foods, and meat-heavy meals can produce higher levels of inflammation.

"When we take processed foods out of our diets, whether that’s meat, dairy, or shelf-stable store-bought items, it helps to reduce inflammation," Papadakis tells Bustle. A long-term study of vegetarians published in Public Health Nutrition in 2017 found that people who'd been vegetarian for two years or more had lower inflammation markers than meat-eaters, but more work needs to be done to show the impact of part-time vegetarianism on inflammation.

5. You May Ingest More Fiber

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Fiber is a very important part of your everyday diet, and going flexitarian may actually improve your intake during your meat-free days. If you shift to a plant-based diet during the week, Papadakis tells Bustle, it's best to design your meals around fruits, vegetables, nuts and seeds, whole grains, beans, legumes, and extra-virgin olive oil. "These plant foods are very high in antioxidants, vitamins, minerals, and fiber, which are all key components for reducing the risk for chronic disease," she tells Bustle.

A study in The World Journal of Gastroenterology in 2010 found that a semi-vegetarian diet, which included eggs and dairy but only featured fish weekly and meat once every two weeks, proved to be helpful in preventing relapses in people with Crohn's disease, an inflammatory condition of the bowel. The scientists behind the study thought that the moderate amount of fiber in the diet might be partially responsible for symptom reduction. If you have inflammatory bowel disease or a history of gut or digestion issues, it's always a good idea to talk to your doctor before you change your diet.

6. You May Reduce Your Cancer Risk

Plant-based diets have been associated with a decreased risk of some cancers, Ghannoum tells Bustle — but the influence of diet on cancer risk is a very difficult thing to estimate, because genetics and other factors play strong roles, too. Vegetarianism has been linked to a lower risk of colorectal cancer, breast cancer, and prostate cancer in some studies, but other research has found breast cancer isn't affected by vegetarianism at all. There's also not much data on how part-time vegetarianism might affect those outcomes, so it's wise to take any claims that flexitarianism is a cancer-buster with a large grain of salt.

7. Your Gut Microbiome Is Likely To Change

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The gut microbiome, the population of millions of bacteria and microbes that live in our guts, is shaped by our diet — and evidence suggests that cutting back on meat will change it. Going flexitarian can replenish your healthy gut bacteria, Papadakis tells Bustle. Studies have shown that going vegetarian or vegan can substantially change your gut microbiome, though research has tended to focus on people who eat plant-based foods all the time , so it's difficult to know how flexitarianism will affect you in particular.

Switching between vegetarianism and meat-eating doesn't change your gut automatically. "Changing your diet to a meat diet over the weekend may take two to four days to change your microbiome," Ghannoum tells Bustle. "So enjoy some meat at the weekend in moderation. When you switch back to plant-based food, you will hopefully maintain your microbiome gut balance."

The impact of going meat-free during the week is highly individual and depends on how you replace meat on your vegetarian days, but it may be a good way forward if you want to improve your heart health, bowel function, and other health outcomes. Plus, your wallet may thank you. "One of the most underrated benefits of going meat-free for a few days is the reduced cost of food for the week," Papadakis tells Bustle. "Meat is one of the most expensive food products!" Check with your doctor, and see if flexitarianism might be a good way to balance health with a healthy checking account.

Studies cited:

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, 16(20), 2484–2495. doi:10.3748/wjg.v16.i20.2484

Chen, Z., Wang, P.P., Woodrow, J. et al. (2015) Dietary patterns and colorectal cancer: results from a Canadian population-based study. Nutrition Journal. 14, 8. doi:10.1186/1475-2891-14-8

Clarys P., Deliens T., Huybrechts I., Deriemaeker P., Vanaelst B., De Keyzer W., Hebbelinck M., Mullie P. (2014) Comparison of nutritional quality of the vegan, vegetarian, semi-vegetarian, pesco-vegetarian and omnivorous diet. Nutrients. 6, 3. 1318-32. doi: 10.3390/nu6031318.

Derbyshire E. J. (2017). Flexitarian Diets and Health: A Review of the Evidence-Based Literature. Frontiers in Nutrition, 3, 55. doi:10.3389/fnut.2016.00055

Godos J, Bella F, Sciacca S, Galvano F, Grosso G. (2017) Vegetarianism and breast, colorectal and prostate cancer risk: an overview and meta-analysis of cohort studies. Journal of Human Nutrition and Dietetics. 30(3):349-359. doi: 10.1111/jhn.12426

Haghighatdoost F, Bellissimo N, Totosy de Zepetnek JO, Rouhani MH. (2017) Association of vegetarian diet with inflammatory biomarkers: a systematic review and meta-analysis of observational studies. Public Health Nutrition. 20(15), 2713-2721.

Kim MK, Cho SW, Park YK. (2012) Long-term vegetarians have low oxidative stress, body fat, and cholesterol levels. Nutrition Research and Practice. 6(2), 155-61. doi: 10.4162/nrp.2012.6.2.155.

Liguori, I., Russo, G., Curcio, F., Bulli, G., Aran, L., Della-Morte, D., … Abete, P. (2018). Oxidative stress, aging, and diseases. Clinical Interventions in Aging, 13, 757–772. doi:10.2147/CIA.S158513

Penniecook-Sawyers JA, Jaceldo-Siegl K, Fan J, Beeson L, Knutsen S, Herring P, Fraser GE. (2016) Vegetarian dietary patterns and the risk of breast cancer in a low-risk population. British Journal of Nutrition. 115(10):1790-7. doi: 10.1017/S0007114516000751.

Singh, R.K., Chang, H., Yan, D. et al. (2017) Influence of diet on the gut microbiome and implications for human health. Journal of Translational Medicine. 15: 73 doi:10.1186/s12967-017-1175-y

Zimmer J, Lange B, Frick JS, Sauer H, Zimmermann K, Schwiertz A, Rusch K, Klosterhalfen S, Enck P. (2012) A vegan or vegetarian diet substantially alters the human colonic faecal microbiota. European Journal of Clinical Nutrition. 66(1), 53-60. doi: 10.1038/ejcn.2011.141.

Experts:

Dawn Jackson Blatner, RDN, registered dietician and author of The Flexitarian Diet

Dr. Nate Favini, M.D, medical lead at Forward

Dr. Mahmoud Ghannoum, Ph.D., director of the Center for Medical Mycology at Case Western Reserve University and author of Total Gut Balance

Stephanie Papadakis, nutritional consultant and head of Gut of Integrity