Protein Toxicity

Protein Toxicity | The Paleo Diet

Hi Professor Cordain!

My name is Chloe and your book has truly changed my life… All three, to be exact. I love them all! Since adopting the Paleo diet (and following your guidelines in particular) I have lost 30 pounds and reversed PCOS and Hypothyroidism. I am particularly grateful for the Paleo Physicians Network you set up for it lead me to a wonderful doctor who has has helped me progress every step of the way, implementing your wisdom all along.

That said, I am wondering about the protein toxicity you speak of in your book. As I understand the body can only handle 200-300 grams of protein- or 30-40% of calories. Is the 30-40% with regards to a 2,000 or higher calorie diet? I ask because I am on a medically supervised plan where I eat less than that and thus my high protein intake (which feels tremendously great) can make up as much as 50-60%  of my daily calories (on a 1200-1500 calorie plan, consuming 100-150grams of protein/day)

Is this “safe” since caloric intake is lower? Foods are balanced out with ample vegetables, fruits and some healthy fats….

I thank you for work and brilliance and look forward to hearing from you!



Dr. Cordain’s Response:

Hi Chloe,

Thanks for your kind words about the Paleo Diet and congratulations upon your health and weight loss successes.

Protein toxicity can be calculated by using pre-determined figures for maximal urea synthesis in the liver.  These values are expressed as milligrams/Nitrogen/hour/kilogram body weight ^0.75.  Using another equation, it is then possible to calculate a range of values for the maximal protein ceiling in grams per day.  For example from the spreadsheet I have developed to do these calculations, a 60 kg (132 lb) person would have a maximal protein ceiling ranging from 178 g to 245 g whereas a 75 kg (165 lb) person would have a range of 210 to 290 g of protein per day.

To answer your question directly, because you are consuming a hypocaloric diet (calorically restricted) of 1200 to 1500 calories per day then your protein intake could easily reach 50-60 % of your daily energy (600 to 750 kcal and 720 to 900 kcal).  A gram of protein = 4 kcal, so 600 kcal of protein would be 150 grams of protein and 900 kcal of protein would be 225 grams of protein.  You didnt provide me with your current weight, but you should be easily able to ingest 100 to 150 grams of protein without coming close to your protein ceiling.

Best wishes,

Loren Cordain, Ph.D., Professor Emeritus

About The Paleo Diet Team

The Paleo Diet TeamThe Paleo Diet, the world’s healthiest diet, is based upon the fundamental concept that the optimal diet is the one to which we are genetically adapted. The therapeutic effect of The Paleo Diet is supported by both randomized controlled human trials and real-life success stories.

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“4” Comments

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  6. I am hypothyroid and I’ve done so much research on diets for hypothyroid. I am so glad I got to read this I cannot wait to try this diet. I will be buying the book today.

  7. I have Hypothyroidism as well, Hashimotos actually, and everything I did to lose weight didn't work, nothing. I have always preferred bread to meat for any meal and I got to the point where I was eating and eating and still hungry and my weight went so high, I can't even say how much. Despite all my eating though, it was as if my body was starving.
    Paleo has helped me lose 40lbs and I have no more hypo aches and pains in my body and I have far more energy too. I thank you so much for your work and for Paleo and my trainer who introduced me to it. It really is a life changer.
    I thought she was crazy to think I could do a diet like this, being that I loved bread and rarely ate red meat but after giving it a try it's certainly been worth it and I don't crave sugar and carbs like I used to, in fact most things seem too sweet to me now. I have to make everything from scratch.
    I do think I was obsessively hungry because my body was starving nutritionally. Whatever the case, it has been the only thing to work for me.

  8. Hello Loren,
    regarding the Protein Toxicity information that you have provided:

    Does the "Body weight" measurement refer to lean body mass?

    (I assume body fat has little effect on the maximal urea synthesis in a healthy liver?)
    Many thanks

    Rob Lawrence

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