How the calorie content in food is determined

You hear about calories all the time. But what are they really? A calorie is technically the amount of energy required to raise the temperature of one gram of water 1 °C, per Merriam-Webster. Confused? No worries. In plain speak, calories provide energy in the food you consume—and when you exercise, you burn calories as fuel.

How many calories should you eat in a day? “Your calorie needs depend on a lot of factors—including your gender, age, activity levels, whether you’re pregnant or nursing, and more,” says Samantha Cassetty, MS, RD, a weight-loss expert in New York City. “You can also factor in whether you want to lose weight, gain weight, or stay steady.” In a nutshell: The smaller you are, the fewer calories you require. This is how many calories are in a pound.

“Generally speaking, men need more calories than women because of their larger body sizes and greater muscle mass,” explains Cassetty. “Men need up to 3,000 calories, while most women need in the range of 1,600 to 2,000 calories per day.” This range is not at all set in stone, and you can always find a registered dietitian in your area at eatright.org who can help you come up with individualized calorie needs based on your specific needs. Whatever you do, don’t eat below 1,200 calories a day unless you’re working with a medical professional—and even then, you won’t want to stay at that total for long. “It would be really difficult to meet your nutrient needs at 1,200 calories, and you might have a hard time feeling satisfied with that few calories,” notes Cassetty.

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11 easy ways to be healthy at the office
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11 easy ways to be healthy at the office

#1: Stock your desk with healthy, low-calorie snacks

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#2: Don’t keep snacks at your desk at all

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#3: Stand up or walk around once every hour

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#4: Take the stairs instead of the elevator

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#5: Bring workout clothes to the office 

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#6: Pack your own lunch instead of buying

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#7: Fill your water bottle or get a glass of water first thing in the morning

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#8: Get sunlight (work by a window or take a quick walk outside)

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#9: Limit your caffeine intake to once a day

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#10: Stay conscious of your posture

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#11: Keep your desk streamlined and organized

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Here’s the history of the calorie

Believe it or not, the term “calorie” wasn’t a mainstay in American vocabulary until the late 1880s. This was when Wilbur O. Atwater defined the calorie as we know it, in Century magazine. The word became better known with the publication of the “1894 USDA Farmer’s Bulletin.” This publication introduced the first American food database that would be used in the emerging field of dietetics. From then on out, the concept of the calorie was discussed in articles and books—a conversation that continues today, especially when it comes to weight management.

How do manufacturers calculate calorie counts?

Two methods are most commonly used by food manufacturers. One is the 4-4-9 method, which outlines that a protein or carbohydrate contains four calories per gram and fat has nine calories per gram. Take a packet of instant oatmeal, for example, that has 5 grams of protein, 27 grams of carbs, and 3 grams of fat. Based on the 4-4-9 method, this food would contain 155 calories.

Another method commonly used is the system that Atwater created. This method takes into account the amount of energy available from specific foods. For instance, in corn grits, a gram of protein has 2.73 calories, a gram of carbohydrates has 4.03 calories, and a gram of fat has 8.37 grams. In an egg, on the other hand, a gram of protein has 4.36 calories, while a gram of carbohydrates has 3.68 calories and a gram of fat has 9.02 calories.

What about carbohydrates that aren’t digested?

When it comes to non-digestible carbs, a third method for determining calories may be used. This is the 4-4-9 method, adjusted with a factor of two calories per gram—versus four calories per gram—used for soluble non-digestible carbohydrates.

Yet another method is utilized when sugar alcohols come into the picture. General calorie factors are assigned for specific sugar alcohols. For instance, isomalt and lactitol have two calories per gram, while sorbitol has 2.6 calories per gram. Erythritol has 0 calories per gram.

Other methods are used, too

A technique called bomb calorimetry may also be used to assess the number of calories in food. This is a process that involves burning the food to see how much heat it releases. This heat is then directly converted to calories.

Calories are rounded up

On a food’s nutrition label, calories are typically rounded. When a food contains up to 50 calories per serving, the number of calories is rounded to the nearest five-calorie increment. And when food has more than 50 calories per serving, it may be rounded in ten-calorie increments.

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17 healthy foods that are actually dangerous to overeat
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17 healthy foods that are actually dangerous to overeat

Broccoli

First off, it's worth highlighting that most people don't even come close to getting as many vegetables as they should in their daily diet, so don't use this as an excuse to avoid the greens you need. Think of this warning as inspiration to eat the rainbow when it comes to your vegetables. "Broccoli is a superfood that is packed with potent antioxidants known to reduce the risk of cancer and heart disease, but when eaten in very large amounts, broccoli may lead to hypothyroidism (low thyroid)," say the Nutrition Twins, Lyssie Lakatos, RDN, CDN, CFT, and Tammy Lakatos Shames, RDN, CDN, CFT, authors of The Nutrition Twins' Veggie Cure. "This is because they contain thiocyanates, which can make it difficult for your body to absorb iodine. If you're someone who has dealt with thyroid issues in the past, be sure not to consume very large amounts of broccoli." In moderation, though, find out what broccoli can do for your blood sugar.

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Lemon water

The list of health experts and fitness influencers who swear by their morning lemon water is seemingly infinite. "It's a very low-calorie, low-sugar beverage that encourages drinking," explain The Nutrition Twins. "It helps you stay hydrated with its fresh flavor while also providing some immune-boosting vitamin C and antioxidants that may help to protect your cells from damage. However, if you drink a lot of lemon water, the acid from the lemon stays on your teeth and can damage your tooth enamel, which makes your teeth prone to cavities." If you do drink a lot of lemon water, the twins recommend rinsing your mouth afterward and drinking with a straw to minimize contact with your teeth. Here are 12 more potential reasons to love lemon water.

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Almond or plant-based milks

The problem with cow milk alternatives, such as almond, oat, hemp, soy, coconut, and rice milks, is that they're often very processed and have lots of added sugars. In fact, these plant-based milks usually have little of the actual plant, says Keith-Thomas Ayoob, EdD, RD, FAND, associate clinical professor at Albert Einstein College of Medicine. "A glass of the average almond milk, for example, only has about four almonds," he says. Here's why you should stop giving your kids nondairy milks.

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Coconut oil

"More accurately, coconut fat at room temperature is solid owing to its near-total saturated fat content," says Ayoob. Contrary to coconut oil's popularity among the foodie glitterati, there's no actual science to suggest coconut oil is healthy, he says. "Go for extra-virgin olive oil, or canola, grape-seed, or other unsaturated oils as a healthier alternative. And watch out for portion size: No matter the type of oil you're using, they all have lots of calories, so use them sparingly," Ayoob warns. Check out these other compelling reasons to avoid cooking with coconut oil.

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Tuna fish

Tuna is a versatile and inexpensive source of protein, magnesium, zinc, iron, and omega-3 fatty acids. "If, however, you're choosing solid albacore or tuna steaks several times a week, you're likely getting too much mercury, which is a neurotoxin," say the Nutrition Twins. "Mercury poisoning can lead to muscle weakness and vision changes." To avoid any danger, they recommend for the light tuna instead of albacore if you eat tuna regularly. "Pregnant women and children are advised to choose the lowest mercury-containing fish and limit their intake to no more than two times per week." Here's a guide to how much fish you can eat safely.

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Kimchi

Kimchi—a type of pickled cabbage—is a good source of vitamin A, vitamin C, and gut-healthy prebiotic fiber, say the Nutrition Twins. Plus, the kick of flavor is a tasty way to eat your veggies. But it also happens to be high in sodium—the 670 milligrams in a single 100-gram serving translates to almost a third of your recommended maximum sodium intake, they warn. "Combining a few servings of kimchi with the foods you eat in your day and you'll go well beyond the sodium limit, increasing your risk of developing high blood pressure and congestive heart failure," the twins say. That said, kimchi makes the list of 15 foods that nutritionists try to eat every day—in moderation!

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Green tea

Most people can drink green tea with no worries: "It's packed with catechins, powerful antioxidants that help fend off cancer, inflammation, and heart disease," say the Nutrition Twins. "However, the tannins found in green tea can also interfere with the absorption of non-heme iron (iron from plant-based sources), so if you have low iron levels or are at risk for iron deficiency (some athletes, elderly, pregnant women, and vegetarians who don't consume enough iron) avoid drinking green tea with meals and just drink it between them." Look out for these silent signs of an iron deficiency.

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Red wine

Red wine can help boost wellness, but the dose is key. "Red wine can be heart healthy and part of a healthful Mediterranean diet, in modest amounts," says Ayoob. "A modest amount is defined as one five-ounce glass per day for women, two glasses for men." Just don't plan on going dry six days out of the week so that you can guzzle half a dozen glasses of wine on Saturday night. "It's use 'em or lose 'em," says Ayoob. "No saving them up for a big blast on the weekend." And he warns that booze of any kind doesn't mix well with many medications; check with your doctor about the safety of wine with your prescriptions. Learn what happens to your body when you drink a glass of red wine every day.

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Grapefruit and other citrus fruits

While citrus fruits are healthy for most people, Ayoob points out that grapefruit, tangelos, minneolas, pummelos, and more can interfere with a long list of medications, including some statins and antihistamines. "Interaction varies with the medication, but can result in very high blood levels of the drug, or sometimes decreased absorption of the drug, when taken within 72 hours of consuming these citrus fruits." If you're taking medication, always check with your doctor or pharmacist to make sure you can safely consume citrus fruits. Find out which other 17 "healthy" foods can actually be bad for you.

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High-fiber foods

When it comes to weight loss, fiber—the part of a carbohydrate your body can't digest—is incredibly important. It swells in the stomach to make you feel fuller longer, meaning you can lose weight without hunger. However, if you're not used to plenty of fiber in your diet, eating too much at once can cause gas and bloating. "This is typical but annoying and can be socially awkward," says Ayoob. "You really need to introduce fiber gradually and consistently if you're used to a low-fiber diet." Find out what happens to your body when you start eating more fiber.

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Cabbage, kale, Brussels sprouts

"These are great foods with tons of antioxidants, minerals, and vitamins," says Ayoob. "The problem for people on blood-thinning medications, like warfarin, is that they're high in vitamin K, a nutrient that helps blood to clot." (Here are 17 more medication mistakes that could make you sick.) Unless you're at high risk for blood clots, though, the vegetables are good for you.

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Brown rice

While brown rice can be a source of whole grains, it may have higher levels of inorganic arsenic, depending on where it's grown. "Arsenic is present in water and soil and as a result of polluted runoff that can drain into groundwater," explains Maya Feller, MS, RD, CDN, CLC. "This, in turn, increases the arsenic content of water in some areas where brown rice is grown. Issues arise with frequent and consistent exposure; thus, eating brown rice and products with brown rice derivatives every day can result in higher exposure to arsenic." She advises rinsing your brown rice and varying the type of grains you eat. Don't miss these other high-carb foods that could kill you.

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Juices

You might think drinking juice is just like eating fresh whole fruits, but juices are mostly sugar and they don't have any of the belly-filling fiber you get when you eat real fruit. "Consumers are often confused about this and feel that having juice on a regular basis is a healthy choice," says Feller. "The solution, skip the juice and have the whole fruit." Check out these other 13 healthy swaps that will cut your sugar intake.

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Protein powder

Protein is vital for both losing weight and building lean muscle. The average healthy person needs about 1.75 grams of protein per pound of body weight, depending on age, physical activity level, and other health-related variables, says Feller. Does this mean the average person should start to take a protein powder supplement as a part of their daily routine? "I would advise not," she says. "Most of us can meet our protein needs by following a healthy balanced diet. Excessive protein intake can strain the kidneys." Also, some supplements may be contaminated with heavy metals. Feller recommends that you "get clear guidance from a credentialed professional around protein supplementation." Watch out for these silent signs you're eating too much protein.

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Water

We all need plenty of water—and most Americans don't get enough. In fact, we often confuse our thirst for hunger, warns Feller. "However the other side of the coin is over-hydration," says Feller. "Drinking too much water over a short period of time can disturb electrolyte imbalance and in turn result in dangerously low sodium levels." That said, this usually only occurs, she says, if someone drinks gallons of water over a short period of time. Learn the silent signs that you're drinking too much water.

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Nutmeg

Spices are a healthy, low-calorie alternative to heavy sauces and condiments. But a little goes a long way when it comes to adding flavor. "I'm a huge fan of spices—I just wrote a book on their health benefits," says Melina B. Jampolis, MD, author of Spice Up, Slim Down, and founder of SpiceFit. "They're loaded with antioxidant and anti-inflammatory compounds, but in the case of nutmeg, consuming excessive amounts may have a hallucinatory effect and can lead to nutmeg poisoning due to one of the active chemicals in the seeds called myristicin." If you overdo it, you could experience intense nausea, dizziness, and extreme dry mouth. But you'd need to eat at least a tablespoon before you were at risk of any of those effects, so putting a dash in your eggnog or adding a teaspoon to a recipe is totally safe, says Dr. Jampolis.

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Spinach

Before you cut out Popeye's fuel, remember that most people don't get nearly enough leafy greens, including spinach, in their diet. "This is unfortunate because leafy greens are a terrific low-calorie source of vitamins and minerals including magnesium, lutein, folic acid, and vitamin K," says Dr. Jampolis. "But for people with the most common type of kidney stones, calcium oxalate, too much spinach could be problematic, as it contains high levels of oxalate, which could lead to kidney stones in those at risk." Don't miss these other everyday mistakes that put your kidneys in trouble.

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Zero-calorie foods rarely contain zero calories

If a food has less than five calories per serving, its nutrition label may list zero calories, notes the Electronic Code of Federal Regulations. For example, a food with two calories per serving will be noted as having zero calories.

Inaccuracy is allowed

“Declared nutrient values get a 20 percent tolerance for regulatory compliance because it is unlikely that every analyzed batch will have the exact same values,” notes Lauren Swann, MS, RD, a nutrition strategist in Bensalem, Pennsylvania. This means that if a label says a food contains 300 calories per serving, the food could actually have as much as 360 calories or as little as 240 calories per serving.

Calorie counts do differ

Researchers looked at food label accuracy for common snack foods, in a study in Obesity. They tested candy bars, chips, cereal bars, pastries, cookies, crackers, ice cream, nuts, nut mixes, and yogurt using bomb calorimetry. What they found: The measured calorie amounts surpassed the ones listed on nutrition labels by an average of 8 percent. Most products tested were within the 20 percent margin of error allowed by the FDA.

The Atwater system is not perfect

Atwater factors for nuts especially may be inaccurate. In a study in The American Journal of Clinical Nutrition, researchers found that Atwater factors for almonds were overestimated by 32 percent. When using the Atwater factor for almonds, the nut is determined to have 168 to 170 calories per ounce. However, the study authors found that almonds actually contain 129 calories per ounce. In another study in Food & Function, researchers found that how almonds are processed affects how many calories are actually absorbed. For instance, 25 percent fewer calories from whole unroasted almonds are absorbed than what’s listed on the nutrition label. For whole roasted almonds, 19 percent fewer calories are absorbed, and 17 percent fewer calories from chopped roasted almonds are absorbed. Interestingly, this amount does not differ for almond butter.

Calories may be listed differently on imported foods

Eating food from another country? The nutrition label may look different. In Europe, calories are rounded to the nearest calorie. In Canada, if a food contains less than five calories, it’s rounded to the nearest calorie—unless it meets “free of energy” requirements and is labeled with zero calories.

Are calories the end all of food decisions?

Absolutely not. “It’s important for people to know there is far more to nutrition than the caloric value of a food,” says Maya Feller, RD, a registered dietitian in Brooklyn, New York. “In fact, when thinking about important aspects of food, calories are not always on the top of that list. Going the low-calorie route can leave many people feeling deprived and unsatisfied.”

Cassetty agrees. “I’m less concerned about the calories of a particular food and more concerned about the quality of the food itself,” she says. “Multiple studies have linked overly processed food to weight and health problems. So if you’re just looking at calories, you’re not getting the full picture of a food’s impact on your health or weight.” Get an insider look at healthy food decisions when nutritionists reveal their top healthy-eating secrets.

So what should you look at instead?

“It’s not necessary to focus on calories if you get a few things right,” says Cassetty. “Eat mostly whole foods, embrace generous portions of veggies, and cut way back on overly processed snack foods, refined grains, and foods and drinks with added sugars.” And consider whipping up some of your own easy, healthy meals. Try a vanilla smoothie made with Greek yogurt and plant-based ingredients for breakfast, and go with a Mediterranean vegetable salad for lunch or dinner. Homemade almond butter protein balls make a great snack or dessert! Also, give these 15 grilling recipes under 400 calories a try!

Amy Gorin is a freelance writer, registered dietitian, and owner of Amy Gorin Nutritionin the New York City area. Connect with her on Instagram, Facebook, Twitter, and Pinterest.

The post How the Calorie Content in Food is Determined appeared first on Reader's Digest.

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Good Eats: 55 healthy lunches
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Good Eats: 55 healthy lunches

California Chicken, Veggie and Avocado Rice Bowls by Half Baked Harvest | Tieghan Gerard

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New Year's Detox Salad by The Healthy Apple | Amie Valpone

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Garlic and Toasted Tomato Sandwiches by Food & Wine

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Chicken Shawarma with Green Beans and Zucchini by Food & Wine 

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Ratatouille Minestrone by Food & Wine

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Greek Salad Pita Sandwiches by bon appetit

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Big Italian Salad by Food & Wine

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Farro-And-Kale Salad With Olives And Pine Nuts by Food & Wine

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Sesame Ginger Chicken Meatballs by Food & Wine

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Broccolini, Mushroom and Sesame Salad by Food & Wine

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Warm Chicken Sandwiches with Mushrooms, Spinach and Cheese by bon appetit

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Curried Carrot Soup with Maple Roasted Chickpeas by Vegetarian Ventures | Shelly

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Celery, Fennel and Apple Salad with Pecorino and Walnuts by Food & Wine

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Blood Orange, Kale and Lentil Salad by PDXfoodlove | Rebekah Hubbard

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Sweet Potato Crust Quiche by Live and Love to Eat | Claire Marshall

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Kickin' Turkey Club Wrap by Philadelphia Cream Cheese

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Brussels Sprouts with Sausage and Cumin by Food & Wine

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Avo Toast by Crazy Sexy Kitchen | Kris Carr with Chef Chad Sarno

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Charred Broccoli and Red Onion Salad by Food & Wine

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Vegetable Summer Rolls with Chile-Lime Dipping Sauce by Food & Wine

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Curried Cauliflower Tartine with Hummus, Scallion and Chili Oil by Brooklyn Vegetarian | Amy Jennings

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Curried Tofu and Avocado Dip with Rosemary Pita Chips by Food & Wine

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Chopped Salad by Crazy Sexy Kitchen | Kris Carr with Chef Chad Sarno

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Red Lentil Dal with Coconut Milk and Kale by Food & Wine

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Tomato, White Bean and Kale Soup by Fork Knife Swoon | Laura Bolton

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Roasted Root Vegetables with Tamari by Food & Wine

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Chicken Chile Soup by Food & Wine

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Roast Chicken Panzanella by Food & Wine

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Vegan Zucchini Sweet Potato Rolls by Lemons and Basil | Kaylee Pauley

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Vegetarian Chili with Barley, Quinoa and Beans by Food & Wine

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Cucumber Mint Salad with Creamy Lemon-Greek Yogurt Vinaigrette by Food & Wine 

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Kitchen Sink Soba Noodles by Food & Wine

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Moroccan Spiced Roasted-Heirloom Cauliflower Salad by  A Couple Cooks | Sonja & Alex

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Quinoa Wraps with Black Beans, Feta and Avocado by Marin Mama Cooks | Jackie Grandy

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Moroccan Red Lentil with Chard by Feed Me Phoebe | Phoebe Lapine

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Asparagus and Red Quinoa Salad by bon appetit

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Lemon Herb Grilled Chicken by Campbell's Kitchen

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Stewed White Beans with Green Chile and Herbs by Food & Wine

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Veggie and Yogurt Sandwich by Haylie Duff

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Vegan Berry Crunch Smoothie Bowl by Domesticate ME! | Serena Wolf

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Korean Sushi Rolls with Walnut-Edamame Crumble by Food & Wine

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Quinoa Fried Rice by Feed Me Phoebe | Phoebe Lapine

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Mediterarnean Vegetable and Bean Salad by Chef Billy Parisi

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Crockpot Quinoa Lentil Tacos by Begin Within Nutrition | Cristina Cavanaugh

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Pork and Pineapple Fried Rice by Food & Wine

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Shrimp and Vegetable Summer Rolls by Food & Wine

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Mashed Avocado and Chickpea Salad by The Skinny Fork | Amanda Plott

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Quinoa Salad with Spring Vegetables by Food & Wine

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Soba Noodle Bowl with Garlic Sesame Ginger Tamari Sauce by Sunday Morning Banana Pancakes | Heather Poire

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Spicy Green Papaya Salad by Food & Wine

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Summer Chopped Salad with Quick Pickled Vegetables by Food & Wine

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Mexican Stuffed Peppers with Quinoa and Black Beans by Love & Lentils | Sophia Zergiotis

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Warm Spaghetti Squash Salad by Food & Wine

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Thai Brussels Sprouts Salad by food & Wine

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Whole Wheat Rigatoni with Roasted Vegetables by Food & Wine

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Turkey and Lettuce Cups by Kitchen Daily Editors

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Shaved Raw Asparagus with Parmesan Dressing by Food & Wine

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Curried Chicken Salad Sandwich by Kitchen Daily Editors

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Sweet Tomatoes, Cucumbers and Cheese with Balsamic Glaze by ragamuffinrecipes | Maura Boylan

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Hummus Deviled Eggs by Food & Wine

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Tuna Niçoise Sandwiches by Campbell's Kitchen

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