What Is a Semi-Vegetarian Diet, and Is It Healthy? We Asked a Nutritionist
This style of eating seems to be catching on big.
The term "semi-vegetarian" has been trending lately, and I'm thrilled. While there is no formal definition of what a semi-vegetarian diet means, it's clear that a significant percentage of Americans are interested in eating more plant-based meals.
According to the Plant Based Foods Association, total plant-based food sales have risen by 31% since 2017, far outpacing overall grocery sales. And during the pandemic, consumers opted for plant-based foods in a big way. Retail sales of plant-based meats spiked by 148% compared to the previous year, and sales of all plant-based foods were up by 90%.
Here's my take as a registered dietitian on why this is a growing movement, and how adopting a semi-vegetarian diet can improve your health—and the health of the planet.
A semi-vegetarian diet can be personalized
Unlike semi-vegetarian, the terms vegan and vegetarian have formal definitions. Veganism excludes all animal products, meaning no meat, poultry, seafood, eggs, dairy, or any ingredients derived from animal sources, including honey and gelatin. Veganism also generally extends to a lifestyle that involves not using any materials derived from animals, including leather, fur, wool, and silk, nor cosmetics or soaps made with or tested on animals.
Vegetarianism generally means that no meat, poultry, or seafood is consumed, but eggs and/or dairy are included, with no specified amount or frequency. Vegetarians also typically consume meat substitutes, which can range from whole foods, like lentils or beans, to faux meats, such as veggie burgers.
A semi-vegetarian diet would theoretically indicate being a part-time vegetarian, meaning following a vegetarian diet some or even most of the time, but not committing to it fully. That may mean allowing eggs and dairy daily or frequently, but limiting meat, poultry, and seafood to whatever feels right for you.
Among my semi-vegetarian private practice clients, some don't eat dairy, but they do want to eat eggs and seafood. Others avoid eggs yet include yogurt or cheese, and they use animal-derived collagen or take a fish oil supplement. A semi-vegetarian diet can technically include any combination of vegetarian and animal-based foods. But the more plant food you have in your diet, the more you'll likely benefit health-wise. For this reason, it may be best to lay out some sort of structure, such as eating vegetarian Monday through Friday, eating two vegetarian meals a day, or making all home cooked meals vegetarian.
Plant-based meals enhance your health
In a Gallup poll, the top reason cited for consuming less meat was health, with nine out of 10 people naming it as a major factor. Trading meat for nutrient-rich, plant-based alternatives more often can indeed play a major role in protecting your health.
A 2019 meta-analysis, published in JAMA Internal Medicine, looked at plant-based eating patterns, which were defined as eating more plant-based foods and fewer animal-based foods, and the incidence of type 2 diabetes. Researchers found that plant-based dietary patterns were linked to a lower risk of type 2 diabetes, even after adjusting for body mass index (BMI), meaning the effect held true regardless of body weight.
In a 2020 study, researchers looked at data in more than 400,000 US men and women over a 16-year period. They found that a higher intake of plant protein was associated with a lower risk of death from all causes. The link particularly held true for heart disease, which remains the number one killer of both men and women in the US, according to the Centers for Disease Control and Prevention (CDC).
In a recent Stanford study, published in the American Journal of Clinical Nutrition, participants were asked to consume two or more servings per day of either animal protein (mainly red meat) or Beyond Meat for two months, while keeping all other foods and drinks as similar as possible. The subjects then consumed the reverse pattern for another eight weeks. Researchers found that compared to meat, Beyond Meat consumption improved heart disease risk factors, including a reduction in "bad" LDL cholesterol, modest weight loss, and lower blood levels of a compound linked to blood vessel inflammation.
The right plant-based foods to eat
With so many plant based products on the market, it's easier than ever to eat meatless meals. However, filling your cart with frozen vegan pizzas and mac and cheese isn't the best way to benefit from a more plant based diet.
One recent study, published in The Journal of Nutrition, followed over 800 people who were either vegans, lacto-ovo vegetarians, semi-vegetarians, and non-vegetarians. Researchers found that vegans had higher levels of healthy fats, antioxidants, and anti-inflammatory compounds in their bodies. But the outcome was likely because vegan consume more whole plant-based foods, including produce, whole grains, nuts, and pulses.
Pulses, the umbrella term for beans, lentils, peas, and chickpeas, are a filling, nutrient-rich, and versatile plant protein option. This food group has been shown to support healthy weight management and fat loss, even without a reduction in calories. Opt for pulse-based entrees like lentil or black bean soup, and bean and veggie chili or stew. Or replace meat, poultry, or seafood with chickpeas or black-eyed peas in salads, grain bowls, and stir frys.
A balanced semi-vegetarian diet should also include about five cups of veggies and two cups of fruit daily, along with whole grains, such as oats, quinoa, and brown or wild rice, and a variety of nuts and seeds. Plant-based goodies, like vegan ice cream and baked goods, are fine as occasional treats, but they shouldn't crowd out whole, nutrient-rich plant foods.
Semi-vegetarianism helps the planet
The climate crisis has become a public health emergency, and eating fewer animal-based foods is part of the solution.
A Harvard report called The EAT-Lancet Commission on Food, Planet, Health, which calls for a primarily plant-based diet, states, "Food is the single strongest lever to optimize human health and environmental sustainability."
The environmental impact of meat consumption includes the production of greenhouse gas emissions from cattle, a greater use of natural resources, including water and fuel compared with plant food sources, and contamination of water, air, and soil.
A 2019 study, published in the journal Sustainability, found that meatless meals have more than a 40% reduction in environmental impacts. These include carbon footprint, water use, resource consumption, health impacts of pollution, and ecosystem quality.
Simply eating one plant-based meal per day can have a significant environmental impact. For example, each time just one person makes this change, it saves approximately 200,000 gallons of water over one year's time, and the carbon equivalent of driving from Los Angeles to New York City.
How to start a semi-vegetarian diet
Semi-vegetarian diets will likely continue to grow in popularity, and the benefits are numerous. If you're just getting started, try this three step approach.
First, create a plan for which animal-based foods you'd like to keep, and which you're willing to give up (even for a 30-day trial), as well as which plant-based alternatives you'd like to eat more often. Next, decide roughly how many vegetarian or entirely plant-based meals you'd like to eat per day or per week. And finally, seek out healthful, go-to options, including recipes, products to try, and takeout, or meal kit and delivery selections. Have fun experimenting, and pay attention to how your body responds. If you have any special dietary needs, such as food allergies, or a medical condition that requires a therapeutic diet, consider consulting with a registered dietitian who can tailor a semi-vegetarian diet to your body's needs.
Cynthia Sass, MPH, RD, is Health's contributing nutrition editor, a New York Times best-selling author, and a private practice performance nutritionist who has consulted for five professional sports teams.
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