The idea that fats make you fat might be the single most well-known, best advertised lie in all of nutritional marketing.
Not long ago, you'd reach towards the "low-fat" peanut butter, salad dressing, cookies, bread, etc. It was common knowledge that high saturated fats lead to cardiovascular disease and so a trend began. In compliance with "evidence" that saturated fat was bad, food companies reduced the fat in their products and added sugar as not to compromise taste. That left the world consuming higher carbohydrate and sugary diets. Not long after, sugar addiction and obesity epidemics followed.
So, what's the REAL skinny on fat?
Fast forward to 2000's where compiling evidence debunked myths that suggested that high saturated fat diets lead to weight gain and increased cardiovascular disease. It's been a difficult transition for the general public to switch gears- focus less on low fat, low calorie foods and put more emphasis on the exact opposite- higher fats and less concern over calories as a whole.
Fats provide a lot of nutrients and physiological functions that our bodies need for survival.
First and foremost, fats are a source of energy. They are actually the preferred source of energy. Carbs possess this same function, but you're body is only able to store X amount of calories from carbs before it has to be converted and stored as fat. I'm sure you've noticed, but there is no limit on how much fat a person can store, making it a better energy source. So, if you depend on fat for fuel, you can go on for hours and hours without having a dip in energy levels. The idea behind runners training in low heart rate zones, is so they burn fat instead of carbs and therefore can sustain their energy for longer runs. The downfall of relying on excess carbohydrates for your energy needs, is that your metabolism burns through your carbs and if completely depleted leaves you feeling dizzy, hangry, light-headed and reaching for the next carb turning into a vicious cycle.
Have you ever heard of the necessity of pregnant or nursing moms getting enough DHA and EFA? These healthy fats provide the nutrients needed for nerve and brain development. Myelin (sheath surrounding nerves) is made up of essential fatty acids to promote electrical nerve impulses that send messages to your brain and essentially allow you to do EVERYTHING that you can do, like walk. Protect you're most important asset, your mind, and eat healthy fats!
Fats are also the precursor to many hormones made in the body. Without essential fats, hormones can't be made, and normal bodily function is at stake. From getting pregnant, to sex drive, to building muscle and losing fat, etc, an imbalance in hormones can be extremely detrimental!
Fats help to make up the backbones of the membranes in our cells. We have them to thank for maintaining healthy skin and tissues.
What Fats Are The Good Fats?
Saturated Fat: Fatty acids with single bonds. These are the fats that come from animal products such as cheese, milk, eggs and meat. While originally thought to provoke heart disease, current studies found that this was not necessarily the case.
Unsaturated Fat: can be broken down into monounsaturated fat and polyunsaturated fat.
Monounsaturated fat- olive oil, nuts, avocados.
Polyunsaturated fat- walnuts, flaxseed, fish, algae, etc. Your body is unable to make these fats and therefore, must be obtained from your diet. They are ESSENTIAL to health (remember those myelin sheath's we talked about for nerve and brain function?).
Science is constantly researching more and more, but the current verdict is that fats (saturated, monounsaturated and polyunsaturated) are good and should be included in your diet. Some evidence suggests putting more emphasis on unsaturated fats, but eliminating saturated fats is NOT necessary and could be detrimental! Transfats are artificial fats created through industrial process and provide no nutritional benefit and should be avoided. You will find these in packaged foods and often times hiding in labels as "partially hydrogenated oils".
With all that being said, I do want to bring light to the fact that while fats ARE NOT bad, fats are higher in calories than protein and carbs. One gram of fat is 9 calories, where as one gram of carb or protein is 4 calories. While all calories are not created equal, it is still important that you are not taking in more calories than you are burning. A healthy balance between carbs, fats and protein is ideal. Based on specific body types, some people may do better on a higher carb diet and others might do well on higher fat diet. The important thing is to never cut out a food group entirely, as they all provide vital functions to sustaining a healthy life!
If you're interested in learning more about eating scaled to your body type, check out Precision Nutrition's blog post covering the topic.