While most people in Paleo circles agree on the basic premises, some questions are oftentimes the subject of much debate. The question about the optimal amount and ratio of protein, carbohydrate and fat that we should consume is one of them.
I think that many authors fall short in their recommendations and make mistakes that lead people to have wrong ideas about optimal nutrition.
Trying to accurately imitate our ancestors is a recipe for failure and choosing an optimal macronutrient ratio solely based on our observations of the Paleolithic Era can lead to critical mistakes. This is why the question needs to be tackled and answered from different angles.
Adaptability of humans
Biochemical science and anthropology have succeeded together in showing us just how flexible the human body is when it comes to being healthy on different macronutrient ratios; different fuels. The fact that we are so flexible is probably what allowed us to populate and thrive on every corner of the world.
For example, on one side we have the Inuits, healthy on a very high fat and very low carbohydrate diet and the Kitavans also thriving, but on a diet very high in carbohydrates from starchy sources like yams.
It's important to remember though that tolerated doesn't mean optimal and this is why exploring the question of the optimal macronutrient ratios is a very interesting one. Even if the Kitavans and Inuits seemed very healthy, nothing tells us that they wouldn't have been even healthier on a diet with different amounts of each macronutrient.
Very low carb, ketogenic diets
Through the years, very low carbohydrate and zero carbohydrate diets have proven to be therapeutic and helpful for many situations. Those diets are known as ketogenic diets because most of the body's cells start using ketone bodies created from fat for energy when glucose becomes scarce. Some cells do however still need glucose to function properly and that glucose can be made from the glucogenic amino acids in proteins by a process called gluconeogenesis that happens mostly in the liver. Red blood cells and some brain cells are two examples of cells that still need glucose to function.
Ketogenic diets are by nature very high in fat and are actively studied for chronic migraines, seizures, epilepsy and some cancers. In the case of cancer, it's believed that cancer cells thrive on glucose as a source of energy, but aren't able to use ketone bodies very efficiently. Cutting the supply of glucose could then effectively kill the cancerous cells.
There is a flip side to the story though. Long term ketogenic diets can lead to problems where the body thinks its starving and down-regulates thyroid function. Paul and Shou-Ching Jaminet from the Perfect Health Diet also make a good case for the possibility of developing a glucose deficiency. Our brains are very large and need much more glucose than those of other animals and our livers are smaller than those of most animals. The liver is the organ responsible for producing glucose for the brain via gluconeogenesis in the case of a lack from the diet.
Additionally, we have no solid evidence of our ancestors going on extended very low carbohydrate diets. Even Inuits feasted on carbohydrate sources a few times per year, depending on the season. Even if it's tolerable, why not reduce the burden on your liver, which is already heavily taxed by a multitude of things.
The problems of lean meat, high protein Paleo diets
I think some Paleo diet authors have painted themselves in a corner in recommending a diet high in lean meats and low in total carbohydrate. I think that this comes from a background and lingering fear for high fat consumption, but this could lead to failure on the diet in the long term. It's important to understand that fats or carbohydrates are the main sources of energy for our bodies, not proteins. It's perfectly healthy to eat up to 80% of your calories as fat. After all, if you eat a very low or zero carbohydrate diet, are you still going to seek out lean meats?
Fat, especially saturated fat, is the cleanest energy source available to us. Unlike glucose and proteins, the metabolism of saturated fat doesn't create any toxic byproducts that need to be eliminated.
People are led to believe that the fat from grain-fed beef or lamb shouldn't be eaten because of the higher omega-6 levels in the fat tissues. We have to keep in mind though that grain-fed ruminants like beef don't necessarily have more omega-6 fat in their tissues, only less omega-3. Also, the fat in chicken and nuts are much higher in omega-6 fat than any grain-fed ruminant's fat.
Some studies on the composition of the tissues of wild animals show that they are lean most of the time and this is where the idea of eating lean meat comes from. Those studies often fall short in not taking into account fat sources found under the skin, in the bones (marrow, brain) and around vital organs like the kidneys. Also, humans are intelligent and our desire for fat led us to selectively hunt the fattiest animals available depending on the season.
Eating only lean meats and limiting saturated fat can lead to protein consumption in dangerous levels. Over time, excess protein can lead to unhealthy amounts of ammonia, higher cortisol levels and depleted vitamin A stores. Our protein needs are very low comparatively to what most people think, but this doesn't mean that periods of higher protein consumption can't be beneficial. In fact, extra protein can be advantageous in periods of growth or to gain muscle mass or help repair an injury.
Excess protein during pregnancy can be very damaging to the fetus. Traditional cultures understood the importance of fat and reserved some of the most prized fatty foods for pregnant or lactating mothers. They understood instinctively that protein was not the macronutrient to prioritize during that part of life for a woman.
Benefits of protein restriction
In addition to the potential dangers of excess protein, there are also benefits to protein restriction. For example, reduced protein diets promote autophagy, which is a crucially important mechanism used by the immune system to kill pathogens and to recycle junk proteins.
Everything is cyclical, so our diets should be
As there can be advantages and negative consequence to both higher carb consumption and long-term ketogenic states as well as higher protein consumption and protein restriction, only one sound solution to the dissonance seems adequate to solve the puzzle.
To quote a famous song by the band The Byrds:
To everything - turn, turn, turn
There is a season - turn, turn, turn
And a time for every purpose under heaven
A time to be born, a time to die
A time to plant, a time to reap
A time to kill, a time to heal
A time to laugh, a time to weep
Most natural phenomena on earth happen in a cyclical fashion. Here are just a few examples: the hormonal cycles, the seasons, the water cycle, sleep cycles, circadian rhythm, menstrual cycles, lunar cycles, life and death. These are just common examples, but if you look closely at a natural phenomenon, you'll likely find that there is some sort of cycling happening. Oftentimes, this cycling is crucial for the well functioning of the system. Things would go haywire for example if it rained 100% of the time or 0% of the time and this is why the water cycle is so important.
In terms of work and productivity, humans perform much better and are much happier when working on tasks in short and intense bursts than when working long consecutive hours on the same tasks. The same thing happens for resistance training.
Modern society taught us to see most things in a linear and constant fashion mostly to the benefit of industrialization where people are encouraged to act like machines and be constant and predictive. In thinking in those terms, we lost sight of how the body really works and even most people in the Paleo community often try to define what an ideal and constant macronutrient ratio would be.
The human body is always cycling between growth and repair modes. Muscle building is a perfect example of this growth and repair cycle where muscle is broken down to then be repaired and made stronger. We benefit greatly from constantly cycling through different macronutrient ratios and through periods of fasting and feasting. It also places the body in constant guess work where it's forced to stay sharp and prevent any waste.
Earlier in this article, we established that periods of higher protein consumption can be detrimental, but also beneficial in some cases. We also established that a ketosis state has many benefits, but can backfire if followed for a prolonged period of time, especially if the gluconeogenesis machinery is not working well and the brain becomes glucose deprived. The only reasonable solution in this case is through cycling between many macronutrient ratios to experience all the benefits without the pitfalls.
This is also true for periods of intermittent fasting and intermittent feasting. Intermittent fasting, either implemented as a concentrated feeding window during the day or as a complete fasting day once in a while, is well known for its benefits in prolonging lifespan, enhancing immunity and recycling junk proteins. A less popular concept though is intermittent feasting. In such periods, large amounts of fat and carbohydrates can be consumed and benefits are seen in the up-regulation of many hormones, especially hormones produced by the thyroid gland. In other words, feasting once in a while is a therapeutic way to tell the body that you aren't starving, that there is an abundance of food and that all your metabolic systems can work on full speed.
It also makes perfect sense on an anthropological level. It's nearly impossible that our ancestors of the Palaeolithic constantly ate the same ratio of protein, carbohydrates and fat throughout the seasons, hunts and periods of their lives.
The best macronutrient ratio to default on
Between beneficial fasting and overfeeding periods, between periods of protein restriction and periods of extra protein consumption, one might wonder about the optimal macronutrient ratios to fall back on.
Those who bring the most sound and logical evidence for an optimal macronutrient ratio are Paul and Shou-Ching Jaminet from the Perfect Health Diet.
Their recommended macronutrient levels for healthy people is at around 20% carbohydrates, 65% fat and 15% protein by caloric intake, not weight. Their reasoning is based around 4 main principles:
- Observations about our ancestors: As stated earlier, observations aren't the best tool to determine something with certitude, but the fact that most of our ancestors ate a diet high in fat, moderate to low in protein and moderate in carbohydrates gives us a good clue to look into. The hunter-gatherer diets for which we have data tend to roam around 20% carbs, 65% fat and 15% proteins by calories. Remember that none of our ancestors ate or favored lean meats other than in periods of scarcity and starvation. Studies about the fatty composition of wild animal tissues who show generally lean tissues doesn't take into account the subcutaneous fat, bone marrow fat and fat found in the brain and around the loin as well as the kidneys.
- Composition of human breast milk: Human breast milk is 39% carbohydrates, 54% fat and 7% protein. The brain is the main organ in the body that needs glucose and infants need much more energy to the brain than adults so this is why the carbohydrate fraction of milk is probably higher than the adult's optimal need. What's interesting in the macronutrient ratios of human milk is the high fat and low protein content.
- Composition of our own tissues: An average lean male is composed of about 30 lbs of fats and 23 lbs of protein (93 lbs of water). If we reserve the portion of carbs used by the brain, it leaves us with a proportion of about 60% fat and 20% protein for the other body tissues. It makes sense to eat foods in the ratio that composes your body so that the body can use those macronutrients to rebuild itself or cannibalize itself in case of need.
- Preference of omnivorous animals for high-fat diets: When given the choice, omnivorous animals instinctively chose foods that are healthiest for them. They all choose to eat a high-fat, low to moderate protein and moderate carbohydrate diet. People from traditional cultures also instinctively go for a similar macronutrient ratio.
The recommendations made by Paul and Shou-Ching take into consideration those four factors together. This is also the ratios I now personally recommend because they come from the most convincing arguments available to us at this time.
It goes without saying that there is definitely room to play around with these ratios depending on your own preferences, activity levels and goals. Those ratios are excellent though to prevent any deficiencies or excess of any macronutrient.
Not making diet a math equation
We already know that counting and restricting calories is very often far from the best way to effectively lose body fat. For example, hormonal imbalances and micronutrient deficiencies can be further exacerbated by calorie restriction, which can stop weight loss or even cause additional weight gain once a person returns to a satiating caloric intake.
Things are similar when it comes to macronutrient ratios. We saw earlier that we can thrive on a very large array of macronutrient intake, but that things are probably optimal at around 20% carbohydrates, 65% fat and 15% protein. Knowing about those optimal ratios isn't a reason to that start calculating and measuring everything though. It's merely an underlining guide. Being overly zealous about food doesn't help at all and can make it hard to stick to healthy habits.
Trying to construct every meal around a specific amount of fat, carbohydrate and protein is a form of unnecessary micromanagement and minutiae and often a source of extra stress.
Therefore, mixing things around and cycling through different macronutrient intakes also help avoid falling into the trap of calculating everything. You'll probably realize over time that in the course of a given period of time (e.g. 1 month) the amount of fat, protein and carbohydrate consumed will be around the optimal range, even if you gorged on meat and fat alone for a few days and enjoyed larger amounts of potatoes or sweet potatoes on other days.
We can easily summarize this article in 4 key points:
- We can't rely solely on anthropological evidence and try to mimic our Palaeolithic ancestors for optimal health. This applies to specific food choices, but also to the macronutrient ratios.
- The optimal default mix of macronutrients is probably at around 20% carbohydrates, 65% fat and 15% protein for most people. This doesn't mean that we should strive for a perfect ratio at every meal.
- Striving to eat a constant amount of fat, carbs and proteins is simplistic and linear thinking while the better approach should be cyclical. Therefore, there are health benefits in:
- Low carb, ketogenic periods;
- Higher carb, protein restricted periods;
- Higher protein periods;
- Feasting periods;
- Fasting periods;
- Specific conditions can require tweaking of the optimal ratios. Metabolic syndrome and neurological disorders are two examples where lower carbohydrate, ketogenic diets can be desirable.