While the term “clean eating” is one of the hottest eating-style trends of the past few years, it’s leaving consumers, the media, and dietitians alike confused about what the term really means and the benefits it conveys on health.
The core definition of clean eating that most of its advocates agree on is choosing whole foods as they are closest to nature, or in their least-processed state. From there, different interpretations abound, from Paleo to dairy-free, grain- or gluten-free and vegan. But Wendy Bazilian, DrPH, MA, RD, author of Eat Clean Stay Lean defining the term as such: “Clean eating is about taking steps toward real, wholesome, simpler, minimally-processed foods more often (not absolute or always) and away from highly processed foods.” Let’s take a deeper dive into the science behind this healthy food trend.
What is considered processed food?
Most foods undergo at least some processing. Clean eating advocates question how exactly was the product altered. Foods that have certain components, and with them nutrients, removed or have undesirable ingredients added is where processing can turn food away from healthfulness.
According to Dawn Jackson-Blatner, RD, author of The Superfood Swap, “Clean eating is caring, not obsessing, about ingredient quality and doing your best to cut the C.R.A.P.: chemicals, refined sugar/flour, artificial sweeteners/colors/flavors, and preservatives.”
Sometimes foods have nutrients added to them, a type of food processing called fortification, that can help fill disease-threatening nutritional gaps, like folic acid in bread to prevent neural tube defects in embryos, vitamin D in milk to prevent rickets in children, and iodide in salt to prevent goiterism. Vitamin C added to make a sugar-laden fruity beverage have a more Nutrition Facts Panel? That may be another story.
But you don’t have to abolish all packaged foods to eat clean. The way I like to best define clean eating is: Eat more whole foods. When you eat packaged foods, choose those made with wholesome ingredients you’d use in your own kitchen.
The processed food continuum
Most foods fall on what I like to call a processed food continuum. A whole apple plucked from a tree and soon thereafter eaten is a whole food its truest form. However, ingredients are added to pre-cut, bagged apple slices to prevent browning. Canned apples have the skin removed and usually sugar added to their liquid. Apple juice is free of pulp and skin, resulting in little fiber in the end product. And fruit juice cocktail may contain apple juice, but plenty of added sugar, too.
Rather than avoiding all processed foods, I prefer using the term “highly processed foods” to describe a less desirable food stripped of good nutrients and filled with ingredients that aren’t doing you any favors. There are plenty of other compelling reasons why whole foods are better than highly processed foods. Here are some of my favorites.
Whole grains are better than refined grains
The Dietary Guidelines for Americans 2015-2020 promote that at least half of all grains should be whole, meaning containing the bran and germ, not just the endosperm. However, there is not a single age group meeting this recommendation. In fact, the Guidelines recommend limiting refined grains. The bran and germ contains important nutrients like fiber, iron, zinc, and magnesium, while refined grains are associated with increased triglycerides (the fat in your blood), which may increase heart disease risk.
Metabolic differences between whole and processed foods
One small study sought out to find the metabolic difference between processed and whole foods. Researchers compared a whole-food sandwich made with multi-grain bread and Cheddar cheese to a processed version made with white bread and American cheese. Both sandwiches contained comparable amounts of protein, carbohydrate, and fat. The people who ate the whole-food version burned significantly more calories post-meal than those who ate the processed sandwich due to the thermic effect of food, meaning more calories were burned digesting the whole-food sandwich.
Another study by Tufts University researchers ran a clinical study and found that people who swapped refined grains with whole-grain versions of the same foods lost 100 more calories per day compared to the control group due to burning more calories and absorbing fewer calories from foods eaten with whole grains.
Whole foods contain no added sugar
A key recommendation of the Guidelines advises consuming less than 10% of calories per day from added sugars by particularly avoiding sugar-sweetened foods and drinks. This translates to no more than 200 calories of added sugar for a 2,000-calorie diet, since in order to eat all of the recommended servings from each food group, too much sugar will put a person over their calorie limit, which may lead to weight gain over time.
Whole foods are free of added salt
The Guidelines recommend consuming less than 2300 milligrams of sodium per day, or about 1 teaspoon salt. I find that when cooking with whole foods, using a moderate amount of salt like 1/4 teaspoon still keeps the sodium levels reasonable while boosting taste. And the evidence shows its not homemade meals that are catapulting American’s sodium intake to 3,440-milligrams per day. The offender is commercially processed foods. It’s important to note, however, that some whole cuts of meat and poultry have sodium solution added for moisture, so read the label.
Whole and expeller-pressed fats versus highly refined oils
Whole foods like nuts, seeds, olives, and avocados offer the good fats monounsaturated and polyunsaturated, plus fiber, potassium, and antioxidants. Even significant protein, in the case of nuts and seeds. When foods are expeller-pressed into oil, many beneficial nutrients still remain — as is the case with extra-virgin olive oil. Oils still remaining in the food go on to be extracted by heat or chemicals and these more refined oils are sold as bottled oil or used in other packaged foods. Sure, they can withstand higher cooking temperatures and endure a longer shelf life, but some nutrients diminish, like fewer polyphenols in “pure” or refined olive oil.
Partially hydrogenated oils, a highly processed oil, contains trans fats, which should be kept as low as possible in the diet, according to the Guidelines, since numerous studies have found an association between these fats and increased risk of cardiovascular disease, partly due to increasing the bad blood cholesterol. Watch out for trans fats in highly processed snacks, sweets, shortening, and fast food, though. Many manufacturers are now using palm and palm kernel oils in its place, which are high in saturated fat.
The unsaturated fats in liquid plant oils, like olive, are still better for your heart than coconut oil due to coconut’s high saturated fat content.
Whole meats and poultry
Whole meats, poultry, and seafood contain more of the nutrients you want, like protein, iron, potassium, and B vitamins — and none of the added stuff you don’t, like salt, sugar, refined flour and refined fats. Saturated fats can be found in whole foods, too, so no matter the level of processing, it’s up to you to choose leaner cuts and trim excess fat.
The two things to watch out for with packaged fruit are added sugar and the removed of fiber. Oftentimes, dried and canned fruits and fruit juices contain added sugar, so being a savvy label reader is important. Canned fruits have the peel removed, reducing the fiber content.
As an apple travels down the processed-food continuum, calories, carbohydrates, sugar and potassium go largely unchanged, yet fiber and vitamin C decrease significantly in unfortified juice. Vitamin C is highly unstable, with more processing deteriorating this water-soluble nutrient.
Full-fat versus low-fat dairy
While full-fat dairy is closest to a whole food, the fact remains that low-fat dairy is recommended by the Guidelines versus whole-milk varieties due to the saturated fat content. Other essential nutrients remain unchanged.
Whole-milk dairy is surging in popularity, however, and there are a few good reasons to favor higher-fat versions. Full-fat yogurt, for example, may not need as much added sugar as non-fat yogurt to become palatable, which may be favorable to heart health since dairy fat may not pose the same threat as added sugars. Full-fat dairy may slow down lactose absorption and decrease blood sugars due to the fat content slowing the absorption of carbohydrate, which could be helpful to diabetics.
It’s important to look at the total context of the diet, though. Dairy fat is considered easier on the arteries compared to the saturated fat in red meat, so choose your foods wisely if you prefer to enjoy the taste of whole-milk dairy while not sacrificing on heart health.
Eat your veggies — any veggies
Not a single age group in America eats the recommended servings of total vegetables per week. In this case, more is more…as in eat more vegetables, however you can get them.
Fresh and plain frozen vegetables are obvious good choices, as well as reduced-sodium canned. Since potatoes (and yes French fries) count as a vegetable, you’re best off with baked, boiled, or oven-roasted at home, versus highly processed versions fried in refined oils.
The bottom line: Whenever possible, cook from scratch at home using whole foods so you’ll have more control over the calories, salt, added sugar, and types of fats you’re eating.
Michelle Dudash is a registered dietitian nutritionist, Cordon Bleu-certified chef consultant, author of Clean Eating for Busy Families, and the creator of Clean Eating Cooking School: Monthly Meal Plans Made Simple.
*This article was written and/or reviewed by an independent registered dietitian nutritionist.