You've probably already been told countless times that fat and sugar are bad for you [1]. You should just omit them from your diet, right? Well, you'd be surprised what the experts think about fat and sugar. One thing is for sure, they are definitely not off the menu for nutritionists. We spoke with Keisha Luke [2], a Toronto-based culinary nutritionist, and her dietary feelings toward fat and sugar may seriously surprise you.

Related:

10 Things You'll Only Understand If You've Gone on a Sugar Detox [3]

The Fat Numbers

First things first: not all sources of fat are created equally. Sure, our bodies need fat, but there are many different sources out there, and what you pick will determine the impact on your body.

Now, not to get all scientific here, but to provide you with a better understanding about fats, you need to know the various kinds. First up are saturated fats, which you'll find primarily in animal proteins, dairy, coconut oil, and butter. Then there are unsaturated fats that are prevalent in plant-based sources like nuts, seeds, and seafood. Trans fats are man-made offerings like margarine, which you should stay away from.

According to Luke, depending on what type of fat you're eating, "[it] may journey through our bodies faster or slower. This is usually broken down into LDL (low density lipoprotein or bad fat) and HDL (high density lipoprotein or good fat.) It's important to understand that our bodies require both, in order to sustain themselves."

But how much does a nutritionist like Luke take in? According to Luke: "Although I am not an advocate of numbers (i.e: calorie counting), I do believe it's important to maintain an adequate amount of good fat in the body without overindulging in the "bad fats." I like to eat anywhere between 15 and 20 percent of good fats — like avocados, olive oil, hemp oil — in my diet daily. This helps to keep my body running optimally."

The Sweet Numbers

The majority of our foods contain sugar in some context or another. Our bodies, and especially our brains, need sugar in order to sustain themselves. Whether we call it galactose, lactose, fructose, or dextrose, sugar is a building block of how our bodies work, and we need it as much as any other vital element. That's why it's crazy to think we should omit it from our diet.

Now before we get too deep, let's address the elephant in the room: sugars are also known as carbs. The difference, according to Luke, is sugar is "a simple carb, which means it runs through the body a lot faster than a complex carb [4], such as a root vegetable like sweet potatoes [5] or yams, which takes longer to process throughout the body." These quick bursts of sugars that provide energy throughout the body are vital to how we live. The quick or simple sugar is the one that gets the most vilification in the dietary world, but it's just as important to have as it gives us an immediate boost of energy.

How much does a nutritionist like Luke suggest eating? Think of the serving size being equivalent to the size of your fist. Keeping this in mind, Luke suggests about two servings of complex carbs daily — especially fruits or veggies. "They assist in the digestive processes, while providing antioxidants in the body," she says. From a measurement perspective, this looks like 20-30 grams of sugar per day.

The key here is to limit your simple sugars and carbs and focus more on the complex varieties, but not to ever completely omit simple, quick energy sugars like Luke suggests. This is about balance. Anyone who tells you that you should completely remove anything as vital as carbs, sugars, or fats from your diet is not looking out for your long-term health.