You’re probably throwing away those leftovers. Here’s why eating them is good for you and the environment.

Between 30% and 40% of America’s food supply is wasted—literally, thrown away—each year, according to the USDA’s Department of Agriculture (USDA). Some of the parts of food that we assume to be junk are not only edible but also nutritious. From peels to stalks to peels and more, sometimes what we assume are leftovers are actually as or more nutrient-dense than the parts we normally eat. If Earth Day has the environment on your mind, using them will benefit you and help reduce the amount of methane, one of the most harmful greenhouse gases released into the air by rotting food in landfills.

Here’s what you need to know.

eat the skins

It’s surprising to me that people peel things, PK Newby, nutrition scientist and founder of Food Matters Media, tells Yahoo Life. He says the skins of many fruits and vegetables, such as carrots, apples, potatoes, eggplants and sweet potatoes, are perfectly edible and are where you get much of the nutritional value.

Newby notes that many peels are rich in fiber, vitamins and minerals. They are also where vegetables and fruits, including nuts, store their protective phytochemicals, which are part of the plant’s immune system and provide similar effects to humans who eat them, according to the University of California, Los Angeles (UCLA). Phytochemicals help prevent cell damage, which means they even protect against the development of cancer.

As a general rule, whatever the plant does for itself, it will do for you when you eat it, Newby says. For example, eggplant is a great vegetable that has the most fiber, and then its rich purple color is bursting with what’s called nasunin, which is a powerful plant chemical, and you’re only going to get that on your skin, he explains. . Nasunin has anti-cancer properties and helps prevent damage to brain cells and slows down the signs of aging. Plants have beautiful bright colors, in part, to attract or ward off pests or different species, so that same benefit goes to the person who eats it.

Similarly, the skin of an apple is the most nutrient-dense part of the fruit. An unpeeled apple has higher amounts of vitamins A, C and K than a peeled apple, and is also richer in calcium and potassium, according to the USDA. The statistics are similar for an unpeeled potato, which contains more vitamin C, potassium, folate, magnesium and phosphate than a peeled potato, according to the USDA.

If you’re concerned about pesticides, don’t sweat it, Newby says. The health benefits of skins outweigh the risk of pesticides, he says. Although removing pesticides from the environment is important to avoid contamination of water, soil and animals, the risk to human health from pesticides on produce is quite minimal, according to the Environmental Protection Agency (EPA). Most pesticide residues that are strictly regulated will be removed simply by washing the produce. Concerns about pesticides in the shells are often misplaced, Newby says. They miss the forest for the trees.

Cook the roots, leaves and stems

The outer leaves, the stems, the whole cauliflower is edible, Newby says, adding that you can roast and eat the entire cauliflower or broccoli plant. That’s where you can save some money and get more nutritional value and less food waste, he says.

Not only do you get more nutrients when you eat a whole fruit or vegetable, you also get more diverse nutrients. Newby says that leaves and roots of the same plant species will differ in their nutrient content. Because plants grow from their roots, that’s where they store energy in carbohydrates in both starch and sugar, Newby explains. Leaves, however, are responsible for photosynthesis, which is made possible by a large amount of vitamins and minerals, including potassium, calcium, phosphorus, magnesium and zinc, according to the Smithsonian Center for Environmental Research, along with the disease-fighting phytochemicals.

The leaves tend to be more nutritious than the roots, simply because they have a better balance of vitamins and minerals, Newby says. In addition, there is also a good dose of fiber in most green leafy vegetables.

He especially likes to roast unpeeled beets along with their leaves. You can also use the whole carrot, but since the greens can be a bit bitter, Newby suggests using them to make a pesto (she likes to say: You can do this with many vegetables that you or your loved ones might not immediately like your family).

Make a nutritious stock

If you’re not sure you can eat a piece of food whole, you can probably still use it to make a hearty and nutritious vegetable broth, advises Newby. Keep a bag in the freezer to collect leftovers like parsley stalks, carrot tops, and the ends of celery, potato, and parsnip stalks over time. You can even save and make use of parts of fruits and vegetables that would not be edible, such as onion skins.

Quercetin, a powerful antioxidant, is found primarily in the outermost layer of onion skin, Newby explains. Not only is quercetin an antioxidant, meaning it fights cell damage from free radicals, it’s also anti-inflammatory and antiviral, and has properties that may help protect against diabetes, heart disease, cancer, and disease neurodegenerative diseases, according to the Icahn School of Medicine at Mount Sinai.

Instead of eating raw onion skins, which are hard to digest and can cause digestive issues, Newby suggests tossing them into a vegetable stock or tomato sauce along with other leftovers. They will eventually strain out of the stock, but you’ll get all those nutrients and you’ve got a beautiful, salt-free stock and you’ve used all that stuff.

While loading up your stock with nutritious leftovers, you’ll also avoid food waste, like 45% of fruit and vegetables worldwide. Newby advocates composting any food you can’t use, but acknowledges that many people may not have access to collection or compost collection sites. Composting is really after the fact, says Newby, who focuses on using as much as possible of the food he buys. I create so little trash and little compost; Don’t throw things away, you’re reducing what gets thrown away, whether it’s in the trash or the compost bin, by using every bit of your produce, Newby says.