Your body needs dietary fats. NEEDS. A non-negotiable. The human body could not sustain life without fat in our diets.
What is Fat?
At a basic level, you consume dietary fat. Your body breaks it down into fatty acids, which enter the bloodstream. Your body then uses these fatty acids to make fat that is in a usable form that it needs for vital bodily functions.
Fats are necessary for:
absorption of certain nutrients
production of important hormones
protection for organs
regulation of body temperature
Like carbs and proteins, some fat sources are healthier than others and they affect the body in different ways. Quality always matters.
There are two main types of dietary fat:
(these terms describe the chemical makeup)
*most foods contain a combination of both.
Saturated Fats: mostly solid at room temperature like butter, meats, and dairy. Most animal products contain high saturated fat, except fish. These are considered the "bad" fats, as they are associated with increased bad cholesterol (LDL), heart disease, and stroke.
The American Heart Association recommends only 5-6% of daily calories come from saturated fats.
Unsaturated Fats: mostly liquid at room temperature like vegetable oils as well as nuts and fish. These are considered "good" fats, as they're linked to higher good cholesterol (HDL) and better blood sugar control.
There are also 2 main categories of unsaturated fats:
Monounsaturated Fats: many plants and plant oils like avocados, nuts, seeds, olive oil, and canola oil. These foods contain mostly monounsaturated fats and are low in saturated fats.
Omega-6: oils such as soybean, sunflower, peanut
Omega-3: fish such as salmon and tuna, walnuts, flax and chia seeds, soy beans
Trans fats (technically "trans-unsaturated fatty acids") are a type of unsaturated fat, too. Trans fat in very small amounts does occur naturally in some animal products, but for the most part, they're artificially crated and added to processed foods.
Companies likely choose to use trans fats due to their low cost and extended shelf life. In the last few decades, more research has been conducted to show that trans fats have adverse health effects and should be avoided.
We can't talk about good fat vs. bad fat without having the cholesterol conversation.
Cholesterol is a type of fat (like how fiber is a type of carbohydrate). Cholesterol is a complicated molecule that is vital to sustain human life, as it makes digestion possible, makes up hormones like estrogen and testosterone, and builds the membranes of our body's 37+ million cells.
There is a difference between dietary cholesterol (what we eat) and serum cholesterol (cholesterol that shows up in your blood tests). Eating dietary cholesterol doesn't necessarily mean your serum cholesterol will increase.
It's so much more complicated than simply saying the consumption of dietary cholesterol causes high blood cholesterol. However, it is pretty clear that consumption of saturated fats leads to increased levels of LDL (the "bad" cholesterol) in our bodies.
If you don't follow a specific diet (such as the ketogenic diet), a good goal for daily dietary fat intake is around 25-35% of your total daily calories. If you're massively restricting calories, it's still essential to incorporate enough fat in your diet. Talk to your qualified health professional for specific recommendations.
A good rule of thumb it to:
eat mostly unsaturated fats
minimize consumption of saturated fats
exchange butter for plant-based oils for cooking
eat oily fish
choose lean, skinless meats
limit processed foods
Fat and Body Weight
Each gram of fat has 9 calories, which might be a reason why it gets a bad rap when it comes to maintaining a healthy weight. It is the most calorically dense macronutrient (compared to protein and carbohydrates at 4 calories per gram). While it's true consuming high calories can lead to weight gain, it's not the fat itself, it's the overconsumption of calories in general. To maintain weight, one must balance the total calories from all foods eaten with daily caloric expenditure.
Fat is a satiating macronutrient, meaning it is likely to make you feel fuller for longer. Because of this, it could lead to easier maintenance of weight.
Side effects of undereating dietary fats:
Infrequent/irregular bowel movements
Weak immune system
*consult with your qualified healthcare professional before making changes to your diet.