The Fat Question: Why fat doesn’t make you fat

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By Margaret Floyd,  NTP HHC CHFS

By Margaret Floyd, NTP HHC CHFS

There’s a big ol’ myth out there that stubbornly refuses to die. It goes something like this: eating fat makes you fat.

From a basic caloric standpoint, this appears to make sense. Fat contains 9 calories per gram, whereas carbohydrates and proteins contain 4 calories per gram. If calories were the only thing to consider, it would stand to reason that if you eat fat, you’re going to gain weight because of the higher caloric load.

Well, first off – let’s clear up the calorie myth. If you haven’t done so already, please read last week’s post on why calorie counting is such a small part of the health and weight puzzle.

So let’s look at exactly what your body is DOING with fat. Is it just about energy storage in the form of chunky thighs and a big belly?

Many are surprised to learn of the vitally important roles of fat in the diet:

  • For one, fat is a structurally integral part of every single cell membrane in our bodies. Read that again. It is structurally essential in EVERY SINGLE CELL in our bodies. That’s a pretty darned important role. We’re not talking just “fat cells”, we’re talking every single cell for every single function in the body.
  • Fats are required in order to properly digest and assimilate those all-important fat-soluble vitamins: A, D, E and K. Conveniently, many foods containing these vitamins also come with the fat required to digest them. For example, the fat in egg yolks allows the body to access the vitamins A and D it’s so abundant in. So maybe Mother Nature had it right after all? This is another reason why pasteurized skim milk fortified with synthetic vitamin D is such a silly idea.
  • Fats are required for the adequate use of protein. So all the egg whites in the world won’t help you out if you’re not eating them with the fats in the yolk to access that protein properly.
  • Fats are a source of energy, and a nice consistent, smooth burning energy at that. In other words, the kind of sustained, even-keeled, constant energy we all long for is right in front of us – in fats. They also slow food absorption, which helps with energy regulation as well.
  • Fats are key players in managing inflammation in your body. Some fats help your body inflame when necessary, other fats help your body anti-inflame. Unfortunately, low-quality fats are in themselves highly inflammatory, but that’s about the processing, not the fat in and of itself.

fat doesn't make you fat |
So we’ve established that fat is an absolutely essential part of our diets and shouldn’t be feared. It’s a big bummer (sorry, couldn’t resist) that we use the same label – “fat” – for this vitally important macro-nutrient as the bodily condition we’re all trying to avoid.

But what about the weight issue? Isn’t dietary fat what resides on my inner thighs?

Here’s something really important to know about fat: it does not trigger the hormonal dance that creates fat storage the way that sugar and other starchy carbohydrates do.

When you eat something sweet, your blood sugar levels increase too quickly, and your pancreas secretes the hormone insulin to take the excess sugar out of your blood. Insulin is a fat storage hormone. It stores that extra sugar first as glycogen, and then as triglycerides (fat) once glycogen stores are full.

When insulin is activated, its partner hormone, glucagon, can’t operate. Glucagon’s job is to mobilize stored sugar back into the blood for energy use. These two hormones are constantly in a dance with each other and cannot be present in the blood at the same time. So either your body is in an energy-burning/mobilizing state (glucagon) or your body is in an energy storage state (insulin).

Sugar mobilizes insulin; fat does not.

It’s that simple. In fact, the fat in a sweet treat will actually help to slow down that sugar spike, and thus reduce the insulin surge, mitigating some of the ill-effects of the sweet. This is why the whole fat-free dessert thing is such a bad idea. Not only are you mobilizing a ton of insulin, you’re also removing the one thing in there that could slow that process down.

Another piece to this puzzle is satiation. The digestion of fats triggers your satiation mechanism. This is why low-fat diets are doomed to fail and such an exercise in fierce willpower. Your body is never satisfied without fat, despite the number of calories (one more reason why calories aren’t the be all and end all).

It’s quite the opposite with sugar or foods converting to sugar quickly in the blood (starchy carbs like bread, pastas, cereal, potatoes, etc…). These foods inspire overeating and binging in part because they don’t satiate and in part because of the insulin reaction we explained above. After insulin has done its job of storing that extra sugar as fat, guess what happens? Your blood sugar takes a big hit and you now are in a low-blood sugar space. What do you crave now? You got it… more sugar.

This means: eating fat makes you fuller sooner and longer. Eating sugar leads to a sugar crash which makes you hungrier sooner and in a position to crave more sugar. A vicious cycle indeed.

Now, are all fats created equal? Not by any stretch. In fact, industrially processed oils and rancid fats are ubiquitous in the diet and extremely harmful to both our health and our waistlines. But real, unadulterated fat from quality sources used appropriately is a key component of any healthy diet.

Here’s the bottom line: Eating fat doesn’t make you fat. Eating sugar makes you fat.

why fat doesn't make you fat |



Want to switch up your diet so that your body is in fat-burning mode rather than fat-storage mode? Join us for the next group Sugar Control Detox! Get on the list to be the first to find out.


For more reading on fats, check out:

Eat fat, lose weight
The truth about saturated fats
5 Reasons you shouldn’t be afraid of quality fats


  1. Paige


    Great article!

    I’ve started eating unsalted grass fed butter and cut way down on my grains. In addition to losing weight, I feel like I have way more energy!

    The most amazing shift has been that I’m sleeping a lot less. This was never my goal but I’ve gone from having to sleep 10 hours a night to 7.5 hours a night. I wake up with more energy than ever before!

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  3. Chase


    “In fact, industrially processed oils and rancid fats are […] extremely harmful […] our waistlines.”

    Incorrect. In terms of weight loss, a fat is a fat. Your body doesn’t care whether it’s saturated, polyunsaturated and monounsaturated. Now in terms of general health and well-being, yes, it’s relevant. But for weight loss, it’s not.

    Otherwise good articles are invalidated by untruths like this.

    • Actually, Chase, weight loss is about much more than just calories in/calories out. There are many many examples of this, but for one that pertains very specifically to adulterated and rancid fats: these are highly toxic, and our bodies store toxins in fat. No matter how many calories you consume, if you have a toxic burden your body will not allow a certain amount of fat to be shed in order to protect itself, as it will mobilize those toxins into the blood stream and thus endanger organs. So yes, industrially processed oils are very harmful to our health AND our waistlines.

      • sam


        Agree, but more than that. The polyunsaturated oils are toxic and inflammatory in and of themselves. The processing and accompanying rancidity jut makes them worse. Too much Omega-6 in the diet is bad news, no matter how “fresh” and “natural” they may be. Switching to fresh cold-pressed seed oils (which last about two weeks before becoming rancid) wouldn’t solve this problem. PUFAs are toxic and inflammatory merely by being PUFAs.

        • Brianne


          That isn’t true actually. Polyunsaturated fats are very important to overall health. Omega 6 and Omega 3 are polyunsaturated fatty acids, but they are also essential fatty acids. Meaning they serve multiple purposes in the body, but we must ingest them because we cannot synthesize them ourselves. Omega 6 in and of itself is not bad at all. It, in conjunction with Omega 3 play important roles in inflammation management, for example. The problem is that the standard American diet is entirely too high in Omega 6 and too low in Omega 3. For optimal health it is believed these need to be consumed in approximately a 1:1 ratio, but the American diet averages a 10:1 ratio, much too high in Omega 6, not high enough in Omega 3. This imbalance, not the individual oils themselves, leads to increased inflammation and other health problems.

          • Brianne – I agree with you entirely. The imbalance is a critical aspect. Also the quality of the oils – many polyunsaturated vegetable oils (the omega 6s in particular) are extremely over-processed and completely rancid when we eat them and thus very inflammatory regardless of the balance between them and omega 3s. I’m talking specifically about oils like soybean oil, canola, sunflower, safflower, cottonseed – the stuff you see in all processed foods.

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  7. Christina


    Good read 🙂

    Concerning your comment to Chase, how would someone mobilize toxic fat stores?

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  9. leon


    Denovo lipogenesis has been researched and it’s generally accepted that the body turns sugar to fat only when excess amounts of sugar are routinely ingested ie constant overeating of sugar. Even then the cost of conversion from sugar to fat is 30% of the calories consumed. (Hellerstein. Denovo lipogenesis in humans. 1999/Acheson et al. Glycogen storage & denovo lipogenesis during massive carb overfeeding.1988)

  10. sal


    Here are my macroeconomic and caloric intake this past week. Proteins 291 grams, fats 106 grams, and carbs at 120 grams with at least 36 grams of fiber per day. Granted I love to work out lifting and running but I have been resting the past three days. I have been trying to lose weight and get a nice, ripped figure. The bottom line, I was just too heavy. I was stuck at 208 pounds for months, once I changed my diet to all protein and fat, within weeks I am now 194 and dropping fast. I have figured out this, if I can bring my carbohydrate intake below 100, I will be a furnace burning machine. Granted, all my fats came from Avocados and almonds, which are high in fat. I eat whole eggs in the morning, about three to one egg white. 18 grams of fat. Of course chicken breast. It works. All my carbs come from nutrient densed foods only. Nuts/protein bars or shakes/vegetables/fruits/greek yogurt/. I stopped eating legumes, I love lentils, but I stopped. I feel better. No bread,sugar,cakes,candy,soft drinks. A great tip, I juiced vegetables and pour some into my blender with protein shakes. I love it. I firmly believe I will reach my goal weight of 177 pounds, muscle and ripped two months tops. Here is the kicker. I can workout on any workout program, it all works. Sal

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  12. Khoi


    I’ve been researching around the web for a paper but haven’t got the answer to this question: where exactly does fat go after you eat them?
    I know the stored fat and cholesterol in your blood stream are converted from excess glucose, but what happens to the dietary fats????
    I’ve heard talks of its use as a slow energy source? what’s the process and how does it work?

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  14. Harsh


    Margaret is having 150g of olive oil per day bad for you?

    • Clark


      150g of olive oil = 1350 calories of olive oil. Depending on your exercise habits, that probably about half of your daily calories. While you’re going to get calories from the olive oil, it’s void of fiber and micro nutrients. So ya, while those fat calories won’t spike your blood sugar, it’s still not a good idea to consume that many calories of straight up fat.. I mean you would almost be drinking it lol.

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  16. TJ


    In depth article. Sugar, especially added sugar is definitely the worst thing to digest frequently. It’s surprising to see what sugar can actually cause health wise. I’m not a heavy sugar taker but I’ll definitely have to find an alternative for hot drinks!

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  18. George


    What a brilliant article!!
    I have been sharing this for weeks since I found it! So many clients I have who are looking to lose weight and get healthy live off low fat things and wonder why they’re not slimming down.

    Fat is an essential part of our diets and while we should try to reduce the consumption of certain fats and to a degree fat in general (from a calorie point of view), it is important that you have an adequate amount of fats and that you try and get them from things such as animal produce ie. meat, milk, butter, cheese etc. I can’t stand people who come to me and say “I only eat low fat things such as margarine etc. because there’s no fat in it and is therefore healthier for me”.

    This article should be shared everywhere!

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  21. Mike


    I have a question.
    We humans store fat in cells known as adipocytes. My question is, the fat that is stored there exclusively the fat that our body generates out of sugars, or is there also non-human-made fat stored there?

    • @Mike. I’m not sure what you mean by “non-human-made” fat? This might help: our bodies break everything we eat down into its constituent parts and then our body uses it for what it needs – there are many roles for fat in our bodies. Eating fat doesn’t necessarily turn into fat storage. If you eat ANYTHING in excess – sugars, proteins, or fats – it will ultimately be converted into adipose tissue as fat storage. In our fat-phobic culture, it’s usually the excess carbohydrates that get converted to fat storage first. Does that help?

  22. Sam


    Thank you for this article!!!

  23. Alyssa


    What type of diet would help a Type 1 diabetic loose weight? Is it true that where the insulin is injected, that area becomes more fatty?

  24. Tom CHHC


    Unfortunately fat CAN make you fat, if it is consumed in combination with carbohydrates. This is due to the Glycerol-3-Phosphate enzyme, an unavoidable byproduct of carbohydrate metabolism, that binds to intracellular fatty acids to form triglycerides. In triglyceride form, fat cannot exit cells to be used for energy. With constant intake of carbohydrates, the conversion of triglycerides to fatty acids is blocked, thereby leading to fat accumulation in cells, no matter what the source.

  25. Klewy Jinks


    But basically, eating 100 grams of fat will make you weigh (becuase normal people absorb about 95% of fat) about 95 grams more, so it ‘does’ make you ‘fat’…

    It’s great to learn about the other side of fat, but plz don’t leave out vital information, leaving an opportunity for people on diets to think that it’s okay to eat lots of fat.

    • Klewy, it’s actually a lot more complicated than that. How your body metabolizes and stores energy isn’t a straight calories in, calories stored equation. I ate a diet that was about 70% fat when I was pregnant and didn’t put on a lick of extra weight more than normal, all of which came off completely within a few months of having the baby. This is just one example of many. It’s not about straight volume – it’s about quality, your body’s digestion, macronutrient ratios, your toxic load, and much more. One of the first things I do with clients is get them eating more fat, and reducing sweets and starches, and inevitably they lose weight. By your logic, this wouldn’t/couldn’t happen – but it does.

  26. Noemi


    Hi, I am not sold entirely on the fat story…a diet made only of fat and protein is also very high in calories. Now, if the calories don;t count, do you mean that a diet made of let’s say 2000 calories mainly in fat/protein would make me lose weight vs a more balanced diet of 1400-1500calories made of 45% carbs, 25% protein and 30% fat? Thanks

    • Check out this recent study, Noemi:

      It’s actually showing that even when calories weren’t counted, a higher-fat diet with fewer starches was far more effective than vice versa. I’m not saying only eat fat and protein. That would be very imbalanced. But I’m saying that fat is a very important macronutrient and when we don’t eat enough of it (or good quality fats) health problems ensue. I see it in my practice every day.

    • PT Laroque


      If the high protein and fat diet contained around 20% carbs or less then yes you would lose weight faster despite the higher calories.

      I hate calorie counting! Such a bad approach to nutrition!

  27. Kelley


    I love this post! When I look at nonfat vs. lowfat I’m looking at the nutrition facts and if they’re comparable then I get the lowfat. There usually isn’t much difference between the two. I’ve been working with a wellness coach for the last two months now and my fat percentage is FINALLY going down without working out like a fiend! She believes in 90% diet and 10% exercise to change you body for the better. I get some healthy fats like 4 ounces crumbled feta/goat cheese on salad and reduced fat cheese & avocado on sandwiches (with Ezekiel bread which is lower in calories and higher in fiber than any kind of wheat/white bread). All those problems areas are FINALLY started to get leaner. It’s all about making smarter choices about what we put in our body. 🙂

  28. Vicki


    I agree. I have lost 135lbs by changing my diet. The 2 biggest things that I took out of my diet was sugars and carbs and all fried foods. Added exercise and I have never felt better. I crave vegetables and will never go back to unhealthy eating.

  29. Margaret and James: I appreciate your enthusiasm and also happen to agree that fat, well organic fat, is good for us. But you would make your point better with science based reports or documentation. There are so many people who have the same passion and dedication on endless topics, and many of them are flat out wrong. Just sayin….
    Regards, George

  30. Harry


    Say I eat 10,000 calories worth of fat a day.
    Would the body store the excess as fat or get rid
    of it by other means eg. body heat?

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