We clear up all your misconceptions about fats, break down which ones are the most nutritious, and reveal how they impact your weight and heart health.

Fats have been making a nutritional comeback in recent years. Gone are the days of low-fat diets, and even saturated fats like butter and bacon are seeing a revival among the health conscious. We know that fats are important to our brain health, they help us absorb nutrients and they keep our skin looking supple. But with new and conflicting information about fats popping up in headlines all the time, how do we know which ones to choose?

Here are seven things you need to know to make healthy decisions when it comes to eating fats and oils.

1. You shouldn't get more than two to three tablespoons of fats a day.
In recent years, we've heard so much good news about embracing fats in our diets that this Canada's Food Guide recommendation seems to have been lost amidst our enthusiasm for butter. But Health Canada is clear that two to three tablespoons should be the limit and that unsaturated fats are strongly preferred. Nutritionist Rose Reisman points out that there's good reason for this limit: Each tablespoon is 120 calories, so eating too much can quickly lead to weight gain. And although Health Canada is referring to things like cooking oil, salad dressings and margarine in that recommendation, Reisman suggests that other sources of fat you eat—say, that greasy bacon or heavy gravy—should also be taken into account when calculating your daily intake.

2. Fats can be important to weight loss.
Though fats have long been accused of causing weight gain, largely because they offer nine calories per gram (compared to the four calories found in one gram of carbohydrate or protein), cutting them out entirely can actually backfire on your weight-loss goals. "Sometimes I notice if I cut down fat too much, I'm hungry during the day," says Reisman. That's because fat actually slows down digestion and decreases appetite, so it can help you feel full for longer. Just keep the above recommendation in mind so you don't overdo it.

3. Some fats can actually improve your cholesterol levels.
You've likely heard that certain fats can raise bad cholesterol levels, possibly leading to heart problems down the road. But did you know that eating other fats can improve cholesterol levels? Monounsaturated fats (which include canola oil, olive oil and peanut oil) can actually boost your HDL (healthy) cholesterol levels and reduce your LDL (lousy) cholesterol. Polyunsaturated fats (such as soybean oil, corn oil and sunflower oil) can also lower LDL levels. To give your heart an extra boost, omega-3 fats (found in flaxseed, chia seeds, hemp and walnuts) help fight inflammation, potentially reducing your risk for heart disease.

4. Saturated fats might not be bad, but that doesn't mean they're good.
By now, you've likely heard some headlines announcing the return of bacon, as new research suggests that saturated fat might not increase heart disease in the way we once thought. But before you start slathering butter on everything you eat, here are some things to keep in mind: While saturated fats may not kill you, they aren't doing you any favours either. Research shows that, even if they don't cause heart disease, replacing them with unsaturated fats can still reduce your risk of heart disease. Just be sure that you aren't cutting out saturated fats for sugar and other simple carbs. Those carry their own risks for your heart health.

5. Margarine can be healthy—just read the label.
There are some misconceptions that all margarines contain unhealthy trans-fats, but this simply isn't true, says Reisman. For example, Becel is mostly made of heart-healthy canola and sunflower oils, with a small amount of palm oil to stabilize it and some buttermilk powder and salt. You could actually mix up your own margarine with these ingredients at home in your own blender or ice cream maker if you wanted. If you're choosing a margarine, read the label to ensure there are no hydrogenated oils and be wary of hard margarines (or stick margarines), which are typically the ones that contain trans-fats.

6. Some oils that sound healthy really aren't.
Have you ever bought light olive oil thinking it was lower in calories or fat? Unfortunately, that's not what "light" means in this case. "You have to be careful of what I like to call 'health washing,'" says Reisman. Light olive oil actually refers to an oil that is more refined or processed, so it's lighter in taste. If you're looking for oils with the most health benefits, you should be looking for "virgin" or "extra-virgin" on the label. These terms mean the oils haven't been processed so they still contain their natural polyphenols (beneficial compounds that have antioxidant properties).

7. Oils are only as healthy as your cooking method.
Unfortunately, you could be buying the healthiest extra-virgin oils, but if you're cooking them at temperatures that exceed their smoke points, you're doing yourself more harm than good. When an oil is heated past its smoke point, the fat begins to break down and produce free-radicals—molecules that can damage cells. Oils from different sources have different smoke points and, in general, more refined oils have higher smoke points than virgin oils (so that extra-virgin oil might be health, but not in a stir-fry). Reisman recommends using canola, grapeseed and peanut oil for their high smoke points, but she says, if you always cook on a medium heat, you should be safe to use your olive oil.

Interested in introducing some new oils into your cooking? Check out these seven healthy culinary oils.