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Fat Does Not Make You Fat

Fat Does Not Make You Fat

If you’re feeling completely confused about whether you should cut fat from your diet, you are not alone.  But here’s the bottom line: fat does not make you fat or sick.

So, why do so many people believe that fat is bad for you and causes heart attacks?  This all started in the Dr. Key’s Seven Countries Study decades ago that examined heart risk based on lifestyle and dietary habits.  He found that in the countries where people ate more fat—especially saturated fat—there were more cases of heart disease, and he concluded that the fat caused the disease.  But here’s the problem with this study: correlation is not causation.  Just because both fat intake and heart disease were higher among the same population doesn’t mean the heart disease was caused by the fat consumption.  Here’s another way to look at it: Every day, you wake up and the sun comes up, but although these events happen at the same time, you waking up doesn’t cause the sun to come up.

A study that observed this would show a 100% correlation between these two events, but it would be wrong to conclude that you caused the sun to rise. Because of studies like this, we became sidetracked into believing that saturated fat causes heart disease.  But in fact, we are now learning that sugar is the true culprit, not fat.  A review of all the research on saturated fat published in the American Journal of Clinical Nutrition found there was no correlation between saturated fat and heart disease.  And a recent editorial in the British Journal of Medicine hammers home the same point and shatters the myth that fat causes obesity and heart disease.  Researchers have found that, while it’s true that lowering saturated fat in the diet may lower total cholesterol, it’s actually lowering the good kind of cholesterol, the light, fluffy, buoyant LDL that’s not a problem.

When people eat less fat, they tend to eat more starch or sugar instead, and this actually increases their levels of dangerous cholesterol, the small, dense cholesterol that causes heart attacks. In fact, studies show that 75% of people who end up in the emergency room with a heart attack have normal overall cholesterol levels.  What they do have is pre-diabetes or type 2 diabetes.

So, what’s the conclusion here?  Eating a diet with good quality fat and protein prevents and even reverses diabetes and pre-diabetes (diabesity).  And eating sugar and refined carbs cause diabesity.

So, I encourage you to look at the issue of fat and sugar in a totally different way.  Don’t cut out the fat; enjoy it! Eat good fats. Here are my favorite sources of fat:

  • Avocados
  • Nuts—walnuts, almonds, pecans, macadamia nuts, but not peanuts (one recent study showed a handful of nuts a day reduced death from all causes by 20 percent)
  • Seeds—pumpkin, sesame, chia, hemp
  • Fatty fish, including sardines, mackerel, herring, and wild salmon that are rich in omega-3 fats
  • Extra virgin olive oil (a large study showed that those who consumed 1 liter a week reduced heart attacks by 30 percent)
  • Enjoy grass-fed or sustainably raised animal products (I recommend the Environmental Working Group’s Meat Eater’s Guide to eating good quality animal products that are good for you and good for the planet).
  • You can even eat saturated fat like extra virgin coconut butter, which is a great plant-based source of saturated fat that has many benefits.  It fuels your mitochondria, is anti-inflammatory, and it doesn’t cause problems with your cholesterol.  In fact, it may help resolve them.  I have many diabetic patients whose health improves when I get them on diet that’s higher in fat.

I was just talking to researchers from the Joslin Diabetes Center who told me that the low fat recommendations for diabetics promoted by the American Diabetic Association has in fact been harmful, bad advice making diabetes worse!  Their new research shows that diabetics should be switching to a diet that’s about 30% fat, 30% protein, and about 40% low starch vegetables and fruits (carbohydrates).  That turns their previous advice on its head.

So here’s the take-home message: Fat doesn’t make you fat.  Sugar makes you fat.  Eating good fats can actually help you stay healthy.  So, eat good quality fats and real, whole, fresh food, and don’t worry about it.

Now, I’d like to hear from you.  Send in your comments and share your experiences.  How have you noticed fat and sugar affecting you?  What happened with your cholesterol when you changed your diet?  I encourage you to share this newsletter with your friends and family on Facebook and Twitter.  And submit your questions so that, next week, I may make a House Call to you.

Learn more:

Are You Fat Enough?

Time for an Oil Change

Why Eating a Low-Fat Diet Doesn’t Lead to Weight Loss  

Why Cholesterol May Not Be the Cause Of Heart Disease

How to Lower Your Risk Of Heart Disease Without Using Drugs

Mark Hyman MD is the Medical Director at Cleveland Clinic’s Center for Functional Medicine, the Founder of The UltraWellness Center, and a ten-time #1 New York Times Bestselling author.

Comments (55)

  • Very sound advice Dr. H. Since the late 90s in while living in NY, I started to substitute American Bison for beef whenever possible. Generally available in natural foods markets although I once had a supplier directly adjacent to the ranch. Bison are impressive animals. The grass fed meat is free of hormones and additives. It tastes richer than beef with both higher protein and lower fat content. Try some. Note one can get a sample burger in some Fudruckers,

  • In Keys’ 7 countries study, wasn’t there many more countries that were conveniently left out, and when you included all the countries, it was hard to make a correlation to fat causing heart disease?

    Thank you for getting out the word!

  • Thanks for adding your voice to the growing awareness about “good fats.” About 15 years ago, as I researched and then experimented with foods in my daily diet containing good fats, it became very clear that my overall general wellness (health, weight, etc.) moved to a new, higher level … and was quite stable at that level.

    To this day, my regular food choices include olive oil, avocados, nuts, coconut, and other wonderful and tasty whole foods with “good fat.” For example, I have a fabulous “Chocolate Mousse” recipe that is made with avocados … and you’d never know it! Sometimes, I even have a spoonful for breakfast! It’s a hit at parties, too! … and that’s just the tip of the iceberg …. 🙂

  • What are your thoughts on Chestnuts? I certainly just ate my weight in them, ha!

  • My husband and I changed our nutrition a year and a half ago; we’re basically eating low-carb with no sugar or grains (mostly veggies, meat, eggs, cheese, cream, nuts). It has made us both feel and sleep better. He has virtually no sinus headaches now and sleeps like a baby (he used to lie awake nights feeling overheated and stressed about not sleeping). Our cholesterol levels are coming back well within normal range and better than they were when we ate a typical Western diet. We both lost over 20 lbs in the first six months and have maintained that while eating eggs, cheese, butter, nuts… and we never count calories. Overall, this seems to us a way of life that makes sense and we encourage others to try it but people think we’re nuts and that we’re just wrong about it. Or they tell us that it’s fine for us but they could NEVER give up eating sweets, breads, etc. We wonder what will happen as they continue to gain weight, become diabetic and get all kinds of other problems; some of them already have and still refuse to consider changing.

  • Hi, Dr. Hyman! I think that this is incredibly important information for people to read. I have so many people in my family who believe in eating low-fat foods, but when I look at the ingredients of the foods they are eating, they’re packed with soybean oil, chemicals, and things that are just not good for their health. I always tell them to go for full-fat, whole foods, but no one seems to listen. I’ll share this article and hope that the message will sink in sometime. I’m working as a Holistic Health Coach (I graduated from the Institute for Integrative Nutrition) and I love all of the articles, tips, and advice that you share. Thank you for your work.

  • are you saying no sugar at all for a non diabetic? is that possible? well anything is possible i guess. how much sugar a day if any can a non diabetic or pre diabetic have?

    • Sugar is not good for anyone! In fact studies are beginning to show that it is sugar and starches that convert to sugar that is the cause of Alzheimer’s disease and other cognitive disorders. The only sugars I allow are those in a few fruits and berries. Otherwise none. I was diabetic and reversed through a grain free, sugar free diet.

    • Lowcarb (no sugar and less starch) is best for diabetes. is a Swedish doctor who treates diabetes with LCHF (lowcarb – hi fat). I dont have diabetes my self but lost 20Kg in 18 Months by cutting down on carbs.

  • I originally started a diet of about 40% carbs 30% protein and 30% fat and although it was better than a diet in the 50-60% carb range I found that blood sugar remained in the diabetic range with ann A1C of 6.8- 7.5% without medication. I am now on ketogenic diet of 70% fat, 20% protein and 5% carbs and I have had normal fasting and post meal blood sugars for a year. Although I agree with most of this article I have to say that I did not see normal blood sugar numbers at carb levels of 40%. For myself and many others fat must be at 60% and carbs at less than 10% to actually see normal non-diabetic blood sugar. Many doctors like Dr. Richard Bernstein and Dr Eric Westman of Duke University Medical Center agree with the ketogenic type of diet for the treatment of type 2 diabetes.

  • This is very interesting. I have a question for next week house call.
    Can you please share some tips to correct hormonal imbalance( special focus on PCOS, hypothyroid, obesity).

    • PCOS can be triggered by stress as the raw materials that make your stress hormones are the same as the raw materials that make your estrogen and testosterone. When you are stressed for long periods of time, the production of stress hormones “steals” production away from sex hormones and you can get imbalances.

      Insulin resistance is a core piece to PCOS, and stress can also aggravates this. This is how some individuals can be actually underweight and fit and still have PCOS, often triggered by things like overexercise.

      So things like caffeine, work stress, spouse stress, nutrition, meal timing, exercise level/intensity/recovery, all play vital roles.

  • I started putting a tablespoon of coconut oil in my coffee every morning about a week ago, I’ve lost 5lbs, and I don’t crave sweets at all. The one day I had to go without my coffee/coconut oil I had a king size twix for breakfast… I couldn’t rationalize not having it at all… and then I felt awful the rest of the day.

  • I totally agree with doctor, I was overweight before , then I changed my eating habits , lost 70 lbs and became to normal weight. It stayed for a while but after my vacation I started to eat sweets , within last 6 months’ time I gained 25-30 pounds because of the sugar I don’t drink any coffee, tea, no meat either, but I think I ate lots of cakes and sweets. Now I know how I gained weight even though I am vegetarian, because of sugar. I am working on it.

  • I have a question. I have very HIGH HDL (86), but also need to get my LDL down (130), according to my doctor. What do you suggest?

  • Would love to throw in coconut oil as a healthy source of fats. The MCTs are thermogenic and may help support healthy weight management. They have less kcalories per gram than other types of saturated fat (~6.8kcal./g as opposed to 9kcal/g), are metabolized into ketones that your brain loves as fuel, and may yield other health benefits such as antiviral/bacterial/fungal benefits in the body.

    Most importantly coconut oil is heat stable when you use it to cook with, and has a shelf-life of 2 years. It’s also great for the skin and hair…gotta love fats! Thanks for the article.

  • In ‘sugars’ do you include the grain based breads and simple carbs that are converted to sugars? I am trying to convince the wife to quit buying these items and focus on purchasing foods that will spoil if we don’t eat them within a few days. Clarification from a Dr. or ‘anyone other than me’ could be very helpful.

  • I started taking hydrochloric acid pills and enzymes… gave up wheat and dairy… and finally, I’m starting to see changes… I’ve had an under-active thyroid for a few years and think the gluten caused this in itself. Since starting the supplements, I’ve noticed my nails getting stronger and my hair thicker!! Thank you!

  • What shocks me is that I’m 36 years old and just heard of this concept for the first time. And I interned for an epidemiologist/internal health doctor when I was in college.

    I’m a 5’10” guy who weighted 180 lbs. I run about once a week and honestly don’t do much else. I cut out beer and all refined sugars (which included a few servings/day of bread and pasta) and lost 15 pounds in 7 weeks.

    I feel like a million bucks. It’s crazy how my legs and arms where there was seemingly no fat all became more defined and skinnier.

    The best part – I make a full packet of bacon every sunday and eat it over the course of the week and I absolutely stuff myself with the good stuff you’re supposed to eat – salted cashews, sweet potato fries, fruits and vegetables etc…

  • Hello, I completely agree with you that eating fat doesnt make you fat, but how much is too much? I have been advised by a gym that we shouldnt have more than 35grams of fat a day. But my numbers are normally up around the 60gram mark, is this too much?

    • Hi Kate,
      The amount of fat that is appropriate for you is very individualized. If you feel your best and maintain a healthy weight at your current fat intake, this is the best guidance in determining how much fat to include in your diet. Be sure to choose healthy plant fats as your primary dietary fat source (olive oil, avocado, nuts, seeds).

      Did you know you can work with Dr. Hyman’s nutritionists virtually? For personalized nutrition coaching where you can receive 1:1 support with Registered Dietitians, please see:
      Wishing you the best of health,
      Dr. Hyman Staff

  • You mentioned in your article that about 30% fat, 30% protein, and about 40% low starch vegetables and fruits (carbohydrates) to be consumed by a diabetic person. Can you elaborate what comes under low starch vegetables and fruits ?

    • As you might imagine high starch vegetables include things like – corn, potatoes, and peas. Non-starchy vegetables contain high water contents and include leafy greens and the like.

  • I would say Dr. Hyman’s advice is right on, except for one thing: animal fats, which are subjected to high cooking temperatures, are NOT good for you, and can play a role in the development of diabetes.

    • Incorrect Tom. Animal fats are extremely healthy. What you said is the same old tired dogma of years past. Animal fat is highly saturated and very good for high heat cooking as this type of fat does not oxidize when heated to high temperatures. The evidence that saturated fat has been debunked and thrown away.

      Fat does not induce spikes in blood glucose production which would be a good thing if you are a diabetic. Although anecdotal, there are millions of people including diabetics that have completely reversed their condition eating a higher fat diet and restrict their carbohydrate intake. Please do yourself the service of researching those topics that you comment on. It is confusing enough out there. There is plenty of information on the role of fat specifically saturated fat to come to the same conclusion that I have.

  • I also find that sugar is the problem. For instance, I am on a diet with no chocolate, cake, sweets etc but I still have my bacon (which contains fat). This is not a problem at all as I am still losing weight continuously ! Exercise also helps, but remember you need to eat as you need fuel and energy 😉

  • The greatest wealth is health therefore and there are some types of fats which are good and necassary for our body and some types of fats are not good so we should maintain our calories of the day and take only the balanced diet for perfect health.Thanks for sharing this information.

  • I have noticed that I become bloated and gain weight only after eating chocolate, biscuits and cake (All high in sugar). If I eat anything high in fat but with no sugar such as eggs, salmon etc I don’t feel bloated and do not gain weight. In fact when I cut out sugar I lose weight quite quickly. I agree with this article 100%.


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  • Thanks for sharing your knowledge 🙂

    After reading this part:

    “Here are my favorite sources of fat:

    Nuts—walnuts, almonds, pecans, macadamia nuts, but not peanuts…”

    And I am wondering about peanuts – why not them?


    • Hi Arthur!

      Peanuts tend to grow in humid conditions, which predisposes them to mold. While our body can detox some of the mold, the toxic burden after eating too much can be problematic for our systems. Some people become symptomatic due to the inflammation caused by mold and even develop mold allergies. Others have a very acute allergy to peanuts which can be life threatening. Peanuts are actually not a nut, but a legume. For some people legumes can increase an immune response and cause digestive symptoms as well. For this reason and more, Dr. Hyman encourages you to stick to hypoallergenic, nutrient-dense nuts and seeds. Please see Dr. Hyman’s nutrition coaching portal for a personalized plan to help you get the appropriate 1:1 support for learning more about food as medicine.

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  • Body builders have known this since the 1940’s. guys like Steve Reeves talked about low carb/sugar dieting a long time ago. They had impressive physiques and low body fat eating steak, eggs and whole milk. Good to see modern science is finally catching up.

  • I had high cholesterol and was about 10kg overweight. My doctor said to cut down on meat but I didn’t eat much meat anyway, having been vegetarian for many years and now only eating humanely reared meat. I decided to do my own research.

    Looking at the articles on fat cells and insulin on Wikipedia it’s very clear that the ONLY thing that makes you fat is blood glucose from eating sugar and starch. They trigger insulin which make your fat cells grow. If you keep insulin low then your fat cells shrink. The “calories in, calories out” theory is so easily disproved I’m amazed that we’re still being fed that lie.

    Anyway, I started eating more fat and protein, less sugar and starch, and lost 10kg in about 4 weeks. I went back to the doctor for a blood test and my cholesterol was much lower, at a completely normal level. This despite eating more meat, more saturated fat, than I have for years. That suggests the cholesterol is your body’s response to the damage caused by blood glucose, rather than the result of eating saturated fat.

  • I’ve heard about the opinion that fat does not make you fat and I subscribe to this notion. However, I’d like to understand why bears when presented with an abundant supply of salmon, eat only the fattiest parts of the fish, i.e. the skin and discard the rest.

    These bears are trying to pack as much fat to resist the winter during hibernation. It is conceivable bears’ GI systems are different from those of humans and would therefore react differently when consuming fatty foods.

    I would like to hear comments from the experts.

  • If fat does not make you fat then how does the body get rid of excess calories taken in by fat ?

    • Hello Harry,
      Eating healthy fats will help balance your blood sugar and reduce cravings for foods high in sugar and refined carbohydrates. A healthy diet for weight management replaces unhealthy junk foods and excess calories from sugar and carbs with healthy fats. It is still important to avoid over eating even if it is healthy foods.
      Wishing you the best of health,
      Dr. Hyman Staff

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  • I’m competitive Body builder. Have won first in every competition I’ve entered. Have done my entire diet on high fat low carb no sugar diet.
    People freak at what I eat. It’s very difficult to get through to people that fat really does NOT make you fat. I tell people sugar is like a drug. The more u eat the more you want and the hungrier you will become. But even when they see my results they still can’t understand how it works. I came across your Web site and I am forwarding it to people that want help. It’s very informative.
    Thank you.

  • I also would like to add that I compete at 5’6″
    Tall and 136lb body weight on high fat diet with body fat! of only 4%. So I think proof must be in the

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