Confused about which cooking oil is the healthiest? Join the club. Figuring out what type of fat you should eat is like the quantum physics of the food world. We know that trans fat is bad, but aside from that, there's still deafening debate, hundreds of online scare stories, and a ton of questions left unanswered by our tireless Google searches. Is saturated fat totally evil or totally harmless? Does the difference between polyunsaturated fat and monounsaturated fat matter? Are we getting the right ratio of omega-3 fatty acids to omega-6 fatty acids? If we heat our olive oil to a high temperature, is it going to poison us with toxic compounds?  

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We thought it was high time for some hard answers. So we consulted Keri Gans, RD, author of The Small Change Diet, and asked her every single oil-related question we could think of. Here, we present the results. Welcome to our all-inclusive guide to cooking oils:

Let's start with a few basic things to keep in mind when you're choosing an oil:

Remember: There's no cutting calories.
Every oil out there has about 120 calories and 13 grams of fat per tablespoon—there's no variety that's magically lower in calories than all the rest. What really makes cooking oils different is their composition: Each one has a unique ratio of saturated fat to monounsaturated fat (MUFA) to polyunsaturated fat (PUFA). This ratio determines whether the oil is a solid or a liquid, how well it can withstand high temperatures, and what effects it'll have on the human body.

Choose "cold-pressed" and/or "expeller-pressed" when possible.
These terms refer to the way the oil was processed. Cold-pressed oils are pressed at low temperatures, which means they retain all the flavors, aromas, and nutrients that would otherwise be destroyed by heat. Expeller-pressing is another clean way of producing oil: It means that oil was extracted mechanically (i.e., good old fashioned squeezing) instead of chemically.

Pay attention to smoke point.
Smoke point is the temperature at which oils start to break down, lose nutrients, and develop off flavors. (You'll know it's happening if the oil is letting off wisps of smoke.) Some oils have higher smoke points, so they're better for high-heat cooking like deep frying and searing. Other oils have low smoke points, and should probably be reserved for applications like dressing. We've included each oil's smoke point in the list below so you can choose accordingly.

Pick MUFAs for cooking
When you expose oils to heat and oxygen, they go through a process called oxidation. Apply enough heat, and oil forms byproducts called "cooking oil polar compounds." These compounds may be harmful to human health—preliminary research shows they could raise blood pressure, cholesterol, and heart disease risk—but there are still very few human studies.

So don't freak out: You can curb your exposure to these compounds by cooking with oils that are composed mainly of MUFAs rather than PUFAs. Because of their chemical structure, MUFAs are less sensitive to heat and oxidation, and Gans recommends choosing a mostly-MUFA oil (like olive, avocado, canola, sunflower, sesame, soybean, or walnut) for most cooking. But don't worry if you need to make an exception here and there: "Using a PUFA-based oil for cooking every once in a while is perfectly fine," she adds.

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Strive for balanced omegas.
Omega-3 and omega-6 fatty acids are two different types of PUFAs. Why are they important? "A typical Western diet includes far too much omega-6 [found in abundance in packaged foods, many refined plant oils, poultry, eggs, and some nuts and seeds] and far too little omega-3, creating an imbalance that is associated with whole-body inflammation," Gans says. While whole fish and fish oils are arguably the best sources of omega-3s, you can also find them in some cooking oils. "Ideally, it's best to seek out oils with a more favorable ratio of omega-3 to omega-6, like walnut, canola, and flaxseed." But, again, don't freak out: "Ultimately, it comes down to moderation," Gans concludes. "If you use plant-based oils with a higher omega-6 to omega-3 ratio every once in a while, it's not going to be detrimental to your health."

And now, onto our official ranking:

TOP CHOICE: Olive Oil
77 percent MUFA, 9 percent PUFA, 14 percent saturated
Made from: Olives
Smoke point: 375–470F, depending on variety
Pros: It's rich in polyphenols, antioxidant compounds that have anti-inflammatory properties. "Researchers are also looking into how polyphenols can help to prevent cancer, as well as their potential for improving cognitive function and memory," Gans says.
Cons: Has a relatively low smoke point, so it's not always best for high-heat cooking.
Note: Choose Extra Virgin (unrefined) for dressing and low-heat applications so you'll be able to enjoy its robust flavor. Choose Virgin (also unrefined) or Pure (a blend of virgin and refined oils) for pan-frying, roasting, or baking.

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TOP CHOICE: Flaxseed Oil
18 percent MUFA, 73 percent PUFA, 9 percent saturated
Made from: Flaxseeds
Smoke point: Some sources say 225F, but don't use this for cooking
Pros: "Since the oil is more condensed than whole flaxseeds, it provides a greater punch of omega-3s," Gans says. "Flaxseed oil is also a terrific option for individuals suffering from high blood pressure, and studies show that supplementing with flaxseed oil on a daily basis can lower blood pressure and have a cardio protective effect."
Cons: It can go rancid very quickly (even faster if you heat it), so this oil should be stored in the fridge and used for low-temperature applications like dressing salads only.

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TOP CHOICE: Canola Oil
61 percent MUFA, 32 percent PUFA, 7 percent saturated
Made from: The seeds of the canola plant, a crossbreed of the rapeseed plant that's lower in potentially dangerous erucic acid
Smoke point: 400F
Pros: This oil has it all: It's higher in omega-3s than most other plant oils; it's composed of mostly MUFAs, so it's more resistant to heat-related breakdown; and it has a relatively high smoke point, so it's great for all-around cooking.
Cons: Almost all canola grown in the US is genetically modified, so choose organic if you want to avoid GMOs.
Note: Non-organic canola oil is also usually processed using a chemical solvent called hexane, but the trace amounts of hexane found in the finished product are not a threat to your health, Gans says. Still, if you really want to avoid it, choose organic (hexane is not allowed in organic production), cold-pressed, or expeller-pressed canola.

TOP CHOICE: Avocado Oil
71 percent MUFA, 13 percent PUFA, 12 percent saturated
Made from: Avocados
Smoke point: 400F
Pros: This is another oil that's high in MUFAs with a high smoke point, so it's great for cooking. "It's also loaded with vitamin E, which may help to strengthen our skin and immune system," Gans says.
Cons: It can be really expensive.

TOP CHOICE: Walnut Oil
23 percent MUFA, 63 percent PUFA, 9 percent saturated
Made from: Walnuts
Smoke point: 160–200F
Pros: It's one of the plant oils that will give you a healthy omega-6 to omega-3 ratio.
Cons: Its high PUFA content makes it prone to rancidity, and its low smoke point means it's not great for cooking.

SECOND CHOICE: Sesame Oil
39.7 percent MUFA, 42 percent PUFA, 14 percent saturated
Made from: Sesame seeds
Smoke point: 350–410F
Pros: It's got a relatively high smoke point.
Cons: It's doesn't have much by way of nutrients, and it's has an unfavorably high ratio of omega-6 to omega-3.

SECOND CHOICE: Peanut Oil
48 percent MUFA, 34 percent PUFA, 18 percent saturated
Made from: Peanuts
Smoke point: 450F
Pros: The super high smoke point means peanut oil is a great choice for deep-frying.
Cons: It can sometimes be chemically extracted. Pick varieties labeled "roasted," "toasted," or "expeller-pressed" to avoid this, Gans says.

SECOND CHOICE: Sunflower Oil
16 percent MUFA, 72 percent PUFA, 12 percent saturated
Made from: Sunflower seeds
Smoke point: 440F
Pros: This oil has both a high smoke point and a neutral flavor that lends itself well to lots of dishes.Cons: It's comprised of almost entirely omega-6 fatty acids.

SECOND CHOICE: Palm Fruit Oil
39 percent MUFA, 11 percent PUFA, 50 percent saturated
Made from: The fruit (not the seeds) of the oil palm tree
Smoke point: 450F
Pros: It's got nutrients like vitamin E and the antioxidant beta-carotene—even more so if you buy the unrefined version, usually called Red Palm Fruit Oil. It's also known for its long shelf life.
Cons: It's got a higher percentage of saturated fat than most other plant oils—still a red flag according to most nutrition experts.

THINK TWICE: Grapeseed Oil
16 percent MUFA, 70 percent PUFA, 10 percent saturated
Made from: Grape seeds discarded after winemaking
Smoke point: 390F
Pros: It has a relatively high smoke point.
Cons: It's another oil high in omega-6 fatty acids with basically no omega-3s. Plus, there's a small toxicity concern: "Grapeseed oil can occasionally have dangerous levels of harmful compounds called (polycyclic aromatic hydrocarbons (PAHs) due to the drying process, which involves direct contact with combustion gases" says Gans. "Whenever possible, buy organic grapeseed oil, as this means it is produced without any chemical substances."
Note: PAHs are not unique to grapeseed oil—you can be exposed to them by eating charred foods, too. Don't fear grapeseed as a lone source of these compounds.

THINK TWICE: Coconut Oil
6 percent MUFA, 2 percent PUFA, 92 percent saturated,
Made from: The meat of mature coconuts
Smoke point: 350F
Pros: Coconut oil is composed of a special kind of saturated fat called a medium-chain fatty acid (MCFA). MCFAs are burned rapidly by the liver and used for energy instead of being stored as fat. Coconut oil, like palm fruit oil, also has a long shelf life.
Cons: Gans says we shouldn't leap onto the coconut oil bandwagon with abandon just yet. "While the newest research suggests that not all saturated fats are created equal, and coconut oil may be a better option than butter, from a heart health perspective, it still can't compete with unsaturated fats like olive oil," she says.

THINK TWICE: Soybean Oil (& Vegetable Oil)
24 percent MUFA, 61 percent PUFA, 15 percent saturated
Made from: Soybeans. While vegetable oil blends sometimes contain oils from seeds, like canola or safflower, they're usually composed largely of soybean.
Smoke point: 450F
Pros: It's cheap and widely available.
Cons: Just about everything else—in fact, Gans calls this oil one of the worst. "It's almost always refined, and it's typically found in processed foods and snack items," she says. Plus, it's usually genetically modified, and new research shows it may be even more harmful than sugar.

THINK TWICE: Corn Oil
25 percent MUFA, 62 percent PUFA, 13 percent saturated
Made from: Corn germ (the innermost part of the grain)
Smoke point: 450F
Pros: Its high smoke point. Plus, one study found that corn oil was more effective at lowering LDL cholesterol than olive oil.
Cons: "Reduction of LDL cholesterol alone does not mean your heart disease risk is reduced," says Gans. "Also, keep in mind that corn oil has an omega-6 to omega-3 ratio of 49:1. The optimal ratio? 4:1." You probably also know that almost all corn grown in the US is genetically modified, so the corn oil will be, too (unless you buy organic).