Once upon a time, I ate a virtually fat-free diet.
And I had so many newfangled “food-like products” to help me maintain this diet:
- Fat-free “cheese product” (what a sin)
- Fat-free hotdogs (no words)
- Fat-free potato chips (the bag warned that a main ingredient may cause the runs… yummy!)
- Fat-free nutrition shakes (“nutrition”… oh, sweet irony)
- And of course, diet soda
The real kicker is: I thought I was being so healthy.
After all, everywhere I looked, I was being told that fat was bad and fat-free was good. That fat would make me obese and fat-free would make me thin. That fat would give me heart disease and fat-free would keep my arteries clear. This message is unfortunately still being promoted by many, and chances are you too fell for the low-fat dogma (er… BS) at one point or another.
But low-fat diets are unnatural and extremely unhealthy.
Since the beginning of mankind, fat has been a key component of the human diet. Fat-free “cheese product”, hot-dogs, diet soda, etc. on the other hand? Those didn’t enter our diets until about the last century.
When you look through the data, it’s clear that our nation’s decreased intake of natural, healthy, unadulterated fats (like butter and lard) and increased intake of packaged “food-like products”, sugar, and processed fats (like margarine and vegetable oils) correspond directly to our failing health.
A review coauthored by Walter Willett, chair of the department of nutrition at Harvard School of Public Health, sums this very unfortunate situation up perfectly:
It is now increasingly recognized that the low-fat campaign has been based on little scientific evidence and may have caused unintended consequences.
This is because fat plays a number of vital roles in the body.
Fat provides a concentrated source of energy in the diet, keeping you feeling fuller for longer.
Fat is the body’s preferred and most reliable form of energy. Fat is digested very slowly, steadily broken down to provide a long-lasting stream of energy. Carbohydrates, on the other hand, are digested very quickly, causing a spike in blood sugar levels and leaving you hungry (even though I just ate that huge bowl of pasta! You know the feeling…). This is why low-fat diets leave us feeling constantly deprived, and can lead to overeating and ultimately undesired weight gain.
Fat also stimulates the release of cholecystokinin (CCK), a hormone that assists the digestion of fat and protein and is a regulator of appetite. CCK sends a message to your brain that says “Mmmm, we’re satiated.” A non-fat diet, however, will not stimulate the release of CCK nor send this message to the brain, and so, again, can lead to overeating and ultimately undesired weight gain.
It is for these reasons that fat can actually help you lose weight, contrary to popular belief.
Fat is a key component of cell membranes.
You know, cells… those tiny little things of which our bodies are made. We essentially ARE cells — a collection of 60-90 trillion cells — and properly functioning cell membranes are vital for the proper functioning of the body. Cell membranes protect and organize cells, as well as regulate what comes in and out of cells (like nutrients and toxins).
When it comes down to it, healthy cell membranes = healthy cells = healthy body, and we simply can’t have healthy cell membranes without fat.
Fat is necessary for the body’s healing process.
Prostaglandins are hormone-like substances that are responsible for inflammation and anti-inflammation — both of which are necessary for the healing process — and fatty acids are a necessary co-factor in the creation of prostaglandins. The essential fatty acids (omega-3 and omega-6) in particular are responsible for the anti-inflammation process. These fatty acids are considered “essential” since the body cannot create them and they must be obtained through the diet. So if we are eating a low- or non-fat diet and are deficient in these fatty acids, the body will not be able to anti-inflame appropriately and inflammation can get out of control. This can lead to the dreaded chronic inflammation, which is a precursor to many chronic Western diseases.
Fat plays a vital role in hormone regulation.
Hormones regulate almost every function of the body, and fats are a building-block of hormones.
Fats play an especially important role in the formation of the sex hormones. This is one of the reasons extremely thin teen female athletes experience delayed puberty or do not menstruate regularly. Similarly, traditional “fertility diets” contained very high amounts of fat, particularly cholesterol-rich animal fats like eggs, butter, and fish roe.
Fat is needed for the absorption of the fat-soluble vitamins A, D, E, and K.
If we do not have adequate fat in the diet, we won’t be able to properly absorb these vitamins — even if we’re eating above and beyond the RDA of each — and they will simply be excreted, putting you at risk for deficiency.
This is a bit of a problem, since each of these fat-soluble vitamins is necessary for basic life-sustaining processes. For example, vitamin A is required for a healthy immune system, vision, growth, and reproduction; vitamin D regulates mineral balance in the body, which is necessary for building strong teeth and bones; vitamin E is an important antioxidant; and vitamin K is required for blood clotting. Of course, this is just the tip of the iceberg when it comes to these critical vitamins.
Fat is necessary for healthy liver and gallbladder function.
We need fat in our diets to keep bile healthy and flowing. Bile is made by the liver and stored in the gallbladder, and breaks down and emulsifies fats.
When there is an appropriate amount of fat in the diet, bile will consistently be used to digest fat and the bile ducts and gallbladder will be flushed regularly. But with a low- or non-fat diet, less bile is needed and so it just lingers (so to speak) in the gallbladder where it eventually form gallstones. For this reason, it has been shown that people who eat a high-carb, low-fat diet have an increased risk of gallstones.
Now there are 2 reasons we want to avoid stagnant bile: 1) gallstones are an extremely painful experience! And 2) in addition to digesting fats, bile is a primary mechanism through which the body eliminates toxins. For this reason, stagnant bile also affects the liver — when bile is stagnant, the toxins aren’t eliminated quickly enough and this can lead to a congested liver (and a number of other issues as a result).
So how much fat should be included in a healthy diet?
Around 30% of our daily caloric intake should come from healthy fats, 30% from protein, and the final 40% from low-glycemic carbohydrates (like fruits and vegetables).
Of course, everyone’s body is different, so some may do better with less fat while others may do better with more (I personally am one of the latter). Listen to your body — looks for signs like healthy digestion (regularity, lack of gas and bloating), good energy levels, healthy skin, and positive emotional health. When things are working well, you will know it.
But not all fats are created equally…
Some fats are extremely nourishing while others are downright toxic. Unfortunately, there is a lot of misinformation about fats promulgated by the food industry, conventional nutritionists and dietitians, doctors, and even the government. I seek to set everything straight in this post → Which Fats are Healthy?
Sources and Further Reading:
- 6 Graphs That Show Why The “War” on Fat Was a Huge Mistake, Authority Nutrition
- The Questionable Link Between Saturated Fat and Heart Disease, The Wall Street Journal
- Fat, Not Glucose, is the Preferred Fuel for Your Body, Dr. Mercola
- A Metabolic Paradigm Shift, or Why Fat is the Preferred Fuel for Human Metabolism, Mark’s Daily Apple
- Gallstones and Low Carb, Diet Doctor
- Fat Doesn’t Make Your Fat, Dr. Mark Hyman
- Know Your Fats, Dr. Mary Enig
- Nourishing Traditions, Sally Fallon
- Eat The Yolks, Liz Wolfe
- Put Your Heart In Your Mouth, Dr. Natasha Campbell-McBride
- 9 Steps to Perfect Health – #2: Nourish Your Body, Chris Kresser