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Why Fat Won't Make You Fat

The word “fat” can stir up a number of not-so-pleasant emotions, especially for those who are trying to lose weight. After all, eating fat makes you fat, right? 

This whole idea was born around 1984 when the National Heart, Lung and Blood Institute started promoting low fat diets. Saturated fat became the enemy and people turned to margarine and fat-free products in the hopes of losing weight. 

Yet somehow, the promotion of low-fat diets corresponded to an increase in obesity and diabetes rather than weight loss and better heart health. So, what’s the deal? 

First Thing’s First…  

The logic behind limiting fat intake for weight loss is that fats are so calorie-dense that they should be avoided. The first part of this sentence is true; fat packs more than double the calories as carbohydrates or proteins. While one gram of carbohydrates and proteins contains four calories, one gram of fat has nine. 

But the second part of that sentence couldn’t be further from the truth, and here’s why… 

We Need Fat  

Your brain is 60% fat. SIXTY. That’s huge! Fat isn’t just an incredibly brain-friendly nutrient; it’s needed for many other bodily functions including:

- Transporting fat-soluble nutrients like vitamins A, D, E, and K

- Building cell membranes 

- Protecting our organs from trauma and cold

- Keeping us warm (there's a reason why skinny people are constantly cold!) 

- Allowing for communication processes between cells, specifically for our nervous system

- Providing fuel to your body during times of reduced energy intake — or when you’re not relying on carbs for energy (think low-carb diets) 

With the exception of trans fat, we need all types of fats to live, including saturated, monounsaturated, and polyunsaturated fats.

Why Fat Won’t Make You Fat

  1. It stops you from loading on sugar

  • Some people who choose to cut fat out of their diet end up replacing those calories with carbohydrates. But carbohydrates in their simplest form are just sugar, so eating too much can wreak havoc on your bodily functioning. If people aren’t eating the right kinds of carbs either, the problem is only exacerbated. 

2. Fats keep you fuller, longer 

  • Since breaking down carbohydrates into smaller molecules actually starts in your mouth, you can imagine the overall process of digestion doesn’t take long. Of all the macronutrients — carbohydrates, proteins, and fats — carbs are digested the fastest. 

  • Fats take the longest time to break down. Since they don’t mix with water — and our digestive system is a water-based environment — fat molecules need some extra help being broken down. That’s where bile & enzymes come in. Made by the liver and stored in the gallbladder, bile breaks those big fat blobs into tinier drops in the same way that dish soap cuts through the grease on your pan, while enzymes help with additional breakdown. This process takes awhile, meaning you feel fuller for longer. 

3. Fat can be very satisfying 

  • Some hypothesize that cholecystokinin — a hormone released whenever you eat a fat or protein — helps you feel more more satisfied while keeping you fuller for longer. Support for this theory is mixed among researchers, but I can say anecdotally that I usually feel more satisfied when I add some type of fat to my meals! 

4. Low-fat diets are unsuccessful 

  • In 1993, the Women’s Health Initiative Dietary Modification Trial began, which involved asking around 19,500 women between 50 and 79 years of age to lower their fat intake from 38% a day to 20%. Simultaneously, around 29,300 women were asked to follow their usual diet and keep their fat intake the same. After eight years, the researchers found that there were no benefits to the low-fat diet. These women didn’t receive any protection from breast cancer, colorectal cancer, or cardiovascular disease and their weights were generally the same as the women following their usual diet.

  • Another study published in Clinical Nutrition revealed that people who got less than 15% of their calories from fat each day were at a higher risk of metabolic syndrome, likely because most of their calories were coming from carbohydrates. 

​The Bottom Line

Fat is our friend! In fact, refined carbohydrates are associated with more negative repercussions than healthy fats. That being said, too much of anything is bad for us, and that’s the case with fats, too. While we absolutely need it in our diet, I’m not suggesting you gorge down on the stuff all day long. Remember: it packs twice as many calories as carbs or protein. Be mindful of portion sizes or else calories in could easily exceed calories out, leading to weight gain. 

You Tell Me! 

Have a no-carb recipe to share to celebrate the benefits of fat today? Share in the comments below!


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