There is more confusion about macronutrients than ever before. I will clear up the informational mess and give you the best macronutrient ratio for long-term health. It is intended as a starting point for the average person, individual differences aside.
There are numerous diet books and organizations promoting almost every conceivable macronutrient ratio out there. However, they tend to fall into one of five categories:
1. Government Guidelines
- High Carb, Low Protein, Mid Fat (55:15:30)
- All western governments and traditional medical bodies recommend the same diet. For the last 70 years, this has been largely unchanged.
- It was originally based on the lipid hypothesis and Ancel Key’s research which led to the belief that fat, saturated fat and animals foods caused heart disease and were unhealthy.
- Since the research has overturned this outdated view the fat percentage has slightly increased.
2. Vegetarian, Vegan, and Raw Food Diets
- High Carb, Low Protein, Low Fat (70:10:20)
- In recent years, veganism and raw food diets have risen in popularity. They are based on the idea eating animal foods is unhealthy supported by research such as The China Study. In addition, some also claim eating animal foods is unethical and unsustainable.
- Due to the emphasis on plant foods, they omit the major sources of fat and protein (meat, fish, eggs, dairy), and are therefore usually high carb.
- The raw food diet comes from the idea that enzymes contained within raw foods prevent disease, and cooking destroys these. This theory originates from Dr. Edward Howell.
3. BodyBuilder Diets
- High-Mid Carb, High Protein, Low Fat (50:30:20)
- Bodybuilding rose to popularity in the 1970s and they adopted the standard nutritional advice at the time (high carb, low fat).
- These diets are still promoted through bodybuilding classics such as Arnold Schwarzenegger’s modern bodybuilding encyclopedia.
- High protein diets have also risen in popularity. Both carbs and fat have been demonized, therefore protein is the only ‘acceptable’ macronutrient left.
4. Low Carb and Ketogenic Diets
- Low Carb, Mid Protein, High Fat (20:25:55)
- Dr. Atkin’s Diet Revolution is the best selling diet book of all time and started off the modern low-carb trend. It was popular for one reason: it worked!
- Paleo and Primal diets have become popular in recent years and are typically low carb diets.
- Currently, the ketogenic diet is popular which is a very low carb diet (10:70:20). Dave Asprey’s Bulletproof Diet is a well-known version of this.
5. Zone and Other Moderate Diets
- Mid Carb, Mid Protein, Mid Fat (40:30:30)
- The zone diet and other moderate diets attempt to strike a sweet spot between the government guidelines and low carb diets.
- The diets are often designed to reduce inflammation and stabilize blood sugar.
All of these diets are based on outdated research and selectively try to address one or two issues. None of them takes into account the latest research and looks at it with an objective viewpoint. This is exactly what I will do, to find the best macronutrient ratio.
Epistemology: The PURE Study
Perhaps the best population study on health is the PURE study (1). The study covered 18 countries for 10 years and measured total mortality against different macronutrient ratios. Total mortality is the best indicator of long-term health, since it incorporates a vast amount of data about health, including all serious disease.
The study clearly showed the more carbohydrate and less fat one ate the higher their risk of mortality. The macronutrient ratio with the lowest mortality was 47% carb, 17% protein, 36% fat.
This study has attracted some criticism, likely because it rebuts years of nutritional dogma. There are 2 main ones:
- The study included many subjects from China and South Asia, who have a high carb, low fat, but high trans-fat diet. This may have skewed the results and made high carb diets look bad. However, the researchers also examined mortality findings in Asian countries only, and still found the same associations.
- The study did not track sugar intake, therefore high sugar intakes could have made high carb diets look bad. However, the context of sugar consumption is also important: wholefood vs. refined. Sugar may be detrimental only in regards to its glycemic index – how fast it raises blood sugar. A dessert after a large meal will do so less, compared to sweets eaten alone. Really, this criticism is asking for detail the study cannot provide. The study did not measure a lot of things and it would be wrong to single out sugar.
Diet Comparison Studies
Let’s now look at controlled trials which give us a shorter term, but more precise view of macronutrient ratios. The best available data to answer our question is head-to-head diet trials, of which there are 2 key studies (2,3). Both trials ran for 12 months however, subjects reported they adhered most to the diets during the first 2 months. Therefore, I have summarised the 2-month results of these trials in the tables below.
*points assigned to placing for each biomarker (4 for 1st, 3 for 2nd, 2 for 3rd, 1 for 4th), calories not included.
As we can see the clear loser is the Ornish diet, a low fat, high carb, vegetarian diet. Whereas, the winner in both studies is the Atkins diet, the original low carb diet. The Zone diet performed well, in contrast to the LEARN and Weight Watchers diets, the most similar to standard government guidelines. Speaking broadly, these 2 studies show that high fat, low carb diets are better than low fat, high carb diets.
The Macronutrient Ratio of our Ancestors
Human beings have for the majority of our time on earth lived as hunter-gatherers, later branching out into small-scale farming and nomadic livestock farming. Our cereal-based diet is relatively new, only a few thousand years old for most of us. Modern processed foods are even newer, less than 100 years old. In evolutionary terms, this is too short for complete adaptation and is probably contributing to the rise in chronic diseases. The research of Weston A. Price showed groups who had sustained their traditional, preindustrial diets were in excellent health, and free of modern degenerative diseases.
Loren Cordain’s seminal paper estimates the macronutrient ratio of hunter-gatherers to be 22–40% carbohydrate, 19–35% protein, and 28–58% fat (4). There is a wide variation between hunter-gatherer diets, with those in colder climates eating more animal foods and therefore more fat. And those in hotter climates eating more plant foods, and therefore more carbohydrate. However, 73% of groups derived over half their calories from animal foods. So, we can see that hunter-gatherer diets are weighted towards a higher fat, lower carbohydrate diet.
There is currently one meta-analysis of diet comparison studies of hunter-gatherer diets (paleo diet) vs. government guideline diets. This showed that the paleo diet decreased inflammation, insulin resistance, cholesterol and weight, more than government guideline diets (5).
Subjects instructed to eat a paleo diet ending up eating a macronutrient ratio of 30% carb, 25% protein, 45% fat, and subjects instructed to eat a government guidelines diet ate: 46% carb, 20% protein, 34% fat. Again, we can see a higher fat, lower carb diet seems to be superior.
The Maximum Protein Intake
Sometimes I see diets recommending protein intakes over 35%, these are frankly impossible to sustain. Protein intakes above 35% outstrip the liver’s ability to up-regulate enzymes for urea synthesis, this leads to excess ammonia, a byproduct of protein breakdown, which can result in death (hyperammonemia). This is called ‘rabbit starvation’ and was named so by the forest Native Americans who were sometimes forced to survive solely on rabbits. Symptoms include diarrhea, headaches, and fatigue. Explorers like the members of the 1881 artic expedition – the Lady Franklin Bay Expedition, also experienced rabbit starvation and some died as a result.
Optimal Protein Intake: 15-20%
We humans seem to intuitively eat around 15-20% protein. For instance, take the 2nd diet comparison study discussed earlier. Subjects had a mean protein intake of 16.3% before the study, but after 12 months supposedly following the 4 different diets they had an average intake of 19%. The data also shows subjects on the higher protein diets, the Atkins and Zone, initially increased their intake to 26% but afterward slowly reverted to their original, lower intakes. Moreover, subjects in one of the paleo diet trials were instructed to eat 30% protein, but only managed to eat 23% on average.
It seems that humans are designed to seek a 15-20% protein intake, as it is optimal for our needs. Consider the USA’s protein intake, it has remained very stable at 15-17% for (at least) 35 years (6). Also from personal experience, I have found it hard to sustain a high protein diet, there is only so much chicken breast or white fish one can eat.
However most of all, the PURE showed those who had an 11% protein intake had 266% more mortality than those with a 17% intake. You can see from the graph below that mortality rates were lowest at 17%, slightly higher at 15% and 20%, and much higher outside the 15-20% range.
Optimal Fat Intake: 30-40%
Optimal Carb Intake: 40-50%
Now that protein intake is fixed, carb and fat percentages are relative to each other (if one goes up, the other must go down). The data from the PURE study, diet comparison studies, and research on the paleo diet, all indicate that high fat, low carb diets are better. Certainly, the government guidelines are too high carb (55-60%) for a general starting point.
The PURE study is possibly the best data we have for an optimal macronutrient ratio, but the highest fat group stopped at 35.3% and lowest carb group stopped at 46.4%, both had the lowest mortality respectively. Therefore, based on this data alone we cannot justify high-fat intakes.
Cordain’s research on the paleo diet indicated that high-fat diets were more common, however I believe that we have somewhat adapted to our neolithic diets. The 100 or so generations of farming would have naturally selected those best suited to a higher carb, cereal-based diets, even though the adaption is not fully complete.
The Atkins diet was the most superior in the diet trials, however a high-fat diet can be quite unusual to consume for most. It involves eating a lot of cheese, avocados, fatty meat and oils. Moreover, some fatty foods such as cheese are quite nutrient dense, but a diet dominated by them would be less nutrient dense than one including whole food sources of carbs such as fruit, potatoes, and legumes. Also, the long-term effects of low carb diets are relatively unknown and I am hesitant to recommend a very low carb intake.
So a higher fat, lower carb intake than government guideline diets is justified, but there is not enough data to safely recommend very high fat intakes (+40%).
Taking all things into account the estimated optimal macronutrient ratio is 40-50% carb, 15-20% protein, 30-40% fat.
Note: This article does not take into account individual differences, and is only meant as a general starting point.
Note: You may question the relevance of specific macronutrient ratios when nutrition is moving to more of a focus on whole foods. However, the macronutrient ratio you are trying to achieve will determine the types of food you will eat. For instance, a very high carb diet would include little to no animals foods i.e. sources of fat and protein.