If there's a food group that has been debated for decades, it's fat. First demonized by governments in the 1950s as the cause of diet-related diseases, such as heart disease, fat was everyone's favorite scapegoat, until recently. But what is dietary fat, and what is the truth about it?
Today we're going to have a look at dietary fat, and how it might not actually be the root of your body fat struggles.
What is fat?
One of the reasons that people demonize fat so much is because they don't actually understand what fat is, or why it's essential for health and well-being.
Fat is one of the three main macronutrients consumed as part of the human diet. On a chemical level, it's made up of triglycerides, consisting of three fatty acids combined with glycerol.
From a dietary perspective, there are four main types of fats.
Polyunsaturated fats are liquid at room temperature and in the fridge. Common polyunsaturated fat sources include seed oils, such as sunflower and sesame oils.
Monounsaturated fats are usually liquid at room temperature but solidify in the fridge. Common sources include avocados, olive oil and peanut oil.
Saturated fats are solid at room temperature, and have to be quite warm to liquefy. The most popular saturated fat source at the moment is coconut oil, but it can also be found in meats.
Trans-fats occur in trace amounts in natural fats, but generally speaking, they are artificially created. Trans-fats are created when polyunsaturated fats are altered so that they are solid at room temperature. The most common trans-fat is margarine, but it is also commonly used in many baked goods and junk foods.
Why do we need fat?
Fat is an essential part of the human diet for a number of reasons.
By itself, fat is needed for the cell membranes in every cell throughout the body. The brain in particular is mostly fat, and so for optimal brain function, plenty of good fats are needed.
It's also a major source of energy, supplying more calories per gram than any other macro-nutrient. The extra calories that aren't burned are stored in adipose, or fat, tissue. This is an essential function for protecting us from malnourishment and insulates the body.
Fat provides a number of nutrients that the human body needs, including fat-soluble vitamins A, E, D and K. Without fat to help us absorb them, we would be severely depleted in these nutrients that play various roles in eye, skin, immune, skeletal, circulatory and hormonal health, just to list a few.
It is also the number one source of the essential fatty acids, including omega-3 and omega-6 fatty acids. These are required for a number of functions and structures throughout the body, and we can't produce them internally, so they must be consumed through the diet.
Omega-3, in particular, provides a lot of health benefits needed to reverse the damage that disease and injury can cause. It is a potent anti-inflammatory, and it can protect against everything from diabetes to heart disease and can even alleviate pain. Including sufficient fats high in omega-3s is one thing that health experts will agree on.
As well as all of these essential nutrients, fat also plays a role in satiety, keeping you feeling fuller for longer and keeping blood sugars steady. It adds flavor to foods and dishes that could otherwise be bland. While it may not be physically necessary, this is definitely a reason why it's included in our diet.
What is a good fat?
The exact definitions can vary on what a good fat is, but the research supports that a good fat is one that is whole and natural. Good fat will act as a carrier for fat-soluble nutrients and fatty acids that bestow good health.
If we go off this definition, good fats can include avocado, nuts and seeds, oily fish, egg yolks and minimally processed oils such as avocado oil, walnut oil, olive oil, flaxseed oil and coconut oil.
Even fats from animal products can be healthy, particularly if they are grass-fed or pasture raised. These feeding practices usually means that there are more omega-3 fatty acids, which are essential for well-being.
What is a bad fat?
So what is a bad fat then? This is where artificial fats come in—highly processed or chemically altered fats with minimal to no additional health benefits.
Trans-fats in particular are of concern, including fats that have been chemically altered in a way that can cause health issues in the long term. These are often recognizable as vegetable oils that are solid, such as in margarine.
Canola oil is also highly processed, due to it being sourced from a plant that would generally be toxic if not altered.
Palm oil, if from unsustainable sources, can also be considered a bad fat, simply because it is environmentally damaging due to the farming methods that destroy habitats.
Is low fat the way?
So, will you lose weight and lower your disease risk by reducing fat? Not really. While it is definitely beneficial to eliminate artificial fats and fats that come along with junk foods, research suggests that natural fats can be healthy.
Recent studies show that even saturated fat, thought of as the 'bad' fat until recently, is not associated with a higher risk of cardiovascular disease as previously thought—that in fact, it is the excess sugar consumed that can cause real issues with health.
How to include fat in your diet
The best way to include fat in your diet is to include whole, healthy forms of fat, in a level that works best for your body. Some people do feel better in the lower range of fat intake, whereas others are best with higher fat and fewer carbohydrates to keep calories optimal.
For satiety, you're best off including some form of fat at every meal, whether it be a handful of nuts and seeds over your breakfast, some avocado slices in your lunch-time salad, and some oily salmon at dinner will give you a good dose of healthy fats.
References
http://press.endocrine.org/doi/full/10.1210/jc.2002-021480
http://www.onlinepcd.com/article/S0033-0620(15)30025-6/abstract
http://www.bmj.com/content/347/bmj.f6340.full
http://extension.illinois.edu/diabetes2/subsection.cfm?SubSectionID=46
