#293 Is there a Low Carb Diet Mortality Risk? New Study Results

Is there a Low Carb Diet Mortality Risk?

Everyone seemed to think carbs were bad until this new study was published last week.  Is there a way to follow a low carb diet and still live a long life?  In this article, I’ll teach you how to optimize your carbs so that you can avoid the low carb diet mortality risk.

The Dietary Carbohydrate Intake and Mortality Study

In what has to be one of the biggest carbohydrate studies ever done, Harvard University researchers included a total of 447,607 people.  Of these 447,607 people, a total of 46,464 people passed away during the 25-year follow-up of this study.  These Harvard researchers then analyzed their mortality risk based on food questionnaires filled out over the years prior to their deaths.  Here are the results:

1.  If you ate a moderate amount of carbs (40-70% of your total calories) you lived the longest.

2. If you followed a low carb diet (less than 40% of your calories are carbs), you lost about 4 years of life.

3. If you followed a high carb diet (more than 70% of your calories are carbs), you lost around 1 year of life.

How do you explain these results?

As carbs have been blamed for the obesity crisis, diabetes, and just about every other health problem, how can these study results be explained?  The answer is really quite simple.  Just as there are good and bad carbs there are also good and bad proteins and fat.

In the case of this study, people eating the most carbs ate a lot of flour and other processed carbohydrates.  As a result, their lives were cut short.  This fits nicely from what we know from countless other studies.

For the low carb eaters in this study, the problem is that they replaced their carbs with animal proteins and fat.  Indeed, these lost years of life could have been avoided had plant-based proteins and fat replaced their carbs.  Once again, this finding is something that comes up in study after study.

While nutrition studies are hard to do and sometimes reach the wrong conclusion, the results of this study seem believable based on what we already know.  Personally, I really don’t think what percentage of carbs you eat matters provided you are eating a mostly real food plant-based diet.  In other words, if you choose to eat meat it is a very small portion of wild meat.  The bulk of what is on your plate is vegetables and you also have a healthy fat like nuts, seeds, avocado, etc.

How do you find out your carb percentage?

It is really easy to find out what percentage of your calories come from carbs.  Simply download the free version of either Lose It or Cronometer from iTunes or Google play to your smartphone.  If you still use a flip-phone, there is also a free desktop version to both of these apps.

Next, enter in everything you ate today.  Both of these apps will then automatically calculate what percentage of your calories came from carbs.

How to Eat Low Carb and Live a Long Life

Many of my patients swear by the ketogenic diet.  Some of the biggest celebrities in the world are also following the ketogenic diet.  Even my own carbohydrate intake this past week was 40%.  This 40% number was just 1% away from falling into the danger zone according to this new study.

Yes, you can eat low carb and still live a long life according to this study.  The way to do this is to replace your carbs with plant-based fat and protein.

For example, nuts, seeds, avocados, olives, and coconuts are all mostly fat.  Likewise, there is a lot of protein in beans, lentils, and other legumes.

The big take away for me from this study is that unless you want to eat more plant-based you should probably moderate your carbohydrate intake.  If you are trying to lose weight or reverse diabetes with the ketogenic diet, start embracing a much more plant-based way of eating.

Does that mean you have to give up meat and dairy if you want to eat low carb?  Of course not.  However, a 95% plant-based approach is probably optimal. You simply eat a ton of veggies, low-sugar fruit like berries, and replace your other carbs with nuts, seeds, beans, lentils, avocados, olives, and coconuts.  From a mortality perspective, this study argues that this approach is associated with a long life.

Are you trying to cut back on carbs?  Please leave your thoughts and comments below.

Disclaimer Policy: This website is intended to give general information and does not provide medical advice. This website does not create a doctor-patient relationship between you and Dr. John Day. If you have a medical problem, immediately contact your healthcare provider. Information on this website is not intended to diagnose or treat any condition. Dr. John Day is not responsible for any losses, damages or claims that may result from your medical decisions.

  1. I so want to read your afib book-please self-publish-anything to get it to us ASAP. I am stuck and afraid to travel and haven’t been to see my daughter in Alaska for 3 years because I’m so afraid of having an episode. Will do ANYTHING, any diet/lifestyle changes to get rid of this constant fear. Thank you for all you do. Be blessed.

    • Hi Ann,

      So happy to hear you are interested in this book! Still working on it…unfortunately, a well-written book requires a lot of time. In the meantime, I will continue to blog on important atrial fibrillation topics.

      Stay tuned…


  2. Thank you for the information Dr. Day and your discussion of the results of the study.

    I have read that it is okay to be high carb or high fat but not both as that is the recipe for weight gain. It would appear to be so in terms of calories, and notable plant-based diets such as the Ornish diet or the McDougall diet allow for a high carbohydrate intake but very little fat–in this case monosaturated and polyunsaturated fats.

    Outside of an extreme situation, such as reversing cardiac disease, is it important to restrict fats (mono and poly) when eating a higher carbohydrate, whole food, plant-based diet or to restrict carbohydrates when eating higher, plant-based fats diet?

    In addition, how is “high fat” defined in terms of macros? I have read everything from 10 to 30 percent.

    Thank you for any insight you can provide!

    • Hi Tina,

      All excellent questions. Yes, Ornish in his earlier publications restricted even the plant-based healthy fats. In his later publications he has backed off from this approach.

      If you look at cultures who don’t get heart disease, they eat healthy fats like nuts, seeds, etc. We found that in the people we wrote about in our book, The Longevity Plan. As I have yet to find any compelling evidence that nuts or seeds are bad for you, or for your heart, I continue to recommend these foods to my patients.

      As far as “high fat” goes, many in the ketogenic diet environment say you want to be 70% or more of your calories from fat. From a cardiovascular perspective, there aren’t many studies evaluating the impact of that much fat on the heart. However, with the popularity of the diet I’m sure we will soon start seeing studies.

      Thanks for reading!


    • Hi Ellen,

      That is a great question. If you review the medical studies on the impact of eggs to cardiovascular disease, the results are all over the board. And there are passionate people on each side of the debate who cherry pick the studies they want to support their philosophy on eggs.

      From my personal read of the medical literature, eggs in moderation (1 per day) is probably neutral when it comes to heart disease. In other words, eating an egg a day probably doesn’t help or hurt your heart.

      Personally, my cholesterol numbers (especially LDL) is exceedingly sensitive to any cholesterol in my diet. This is something I have tested repeatedly. As eggs are high in cholesterol, I have chosen not to eat eggs based on what it does to my blood tests.

      Hope this helps!


  3. My take away from this study is that it confirms that it’s the type of carbs eaten that make the difference–not exactly new news–this has been touted for the past several years by many health professionals. To me it’s just confirmation on what I need to keep working on! The type of carbos makes all the difference!
    Than you!

    • Hi Joyce,

      I couldn’t agree more! The carbs from sugar versus the carbs in broccoli or kale couldn’t be more different when it comes to health and longevity.


  4. My own experience mirrored yours. I was very sick eating a lot of carbohydrates and switching to quinoa and brown/wild rice had no effect. I replace all my high starches with vegetables and turned myself around. High carb for me now would be a mini- pumpkin from my garden ( seeds and washed peel included) in my morning smoothie with cinnamon, cardamom, and hemp seeds. My A1c and Crp have both gone down and a huge amount of horrible symptoms disappeared over night. I take better use of all greens now ( pumpkin or broccoli ? greens are quite tasty sautéed) I am sometimes tempted by the smells of foods I used to enjoy but nothing can beat the improvement in my quality of life and there is no arguing with my new lab test results.

    • Hi Loren,

      We all have different genes, different metabolism, etc. The key is to test what you are doing like you have done. Having your Hemoglobin A1C and CRP both go down is an excellent effect.

      Your last point is right on…it is important to remember how good you feel when you have optimized your diet so that you aren’t tempted by the junk.

      Thanks for reading!