Protein, Fat, and Carbohydrate: How Much of Each Should You Eat?

food-pie-chartThere are few topics in nutrition that have been subject to as much debate as the intake of protein, fat, and carbohydrate. On one end of the spectrum, there are the proponents of plant-based diets, including many vegans and vegetarians, who advocate a high-carb, low-protein, and low-fat diet, while on the other end, there are those who favor a diet that is very high in fat, moderate-high in protein, and low in carbohydrate.

For the Average Joe with little to no knowledge about nutrition – and even for those with a deeper understanding – all of the conflicting advice on macronutrient ratios and carbohydrate intake that’s being pumped out from blogs, health authorities, and newspapers can make it difficult to know what to believe. For some, the macronutrient ratio and composition of the diet end up being determined by fluctuations in dietary trends, with a low-carb diet for a couple of months, a plant-based template for a period, and then a juice fast for a week or two…

A controversial topic

Why is there so much controversy surrounding the intake of protein, carbohydrate, and fat? One of the most obvious answers to this question is that humans can thrive on a wide variety of different diets. While many animals on this planet have a relatively narrow/constrained species specific diet, humans can be healthy and fit on diets with widely different macronutrient compositions.

The Okinawans in Japan, who are known for being among the most long-lived people on earth, and the Kitavans on the island of Kitava, with their superb health markers, are two examples of traditional people who seem to maintain very good health on a high-carbohydrate, low-protein diet. On the flip side, you don’t have to look far and wide to find healthy traditional populations – such as the Inuit and the Maasai – who eat a diet that is high in fat and moderate-high in protein. This clearly doesn’t mean that all of these diets are equally healthy or that the macronutrient ratio doesn’t matter, but it does highlight one of the reasons why there is so much controversy surrounding how much protein, fat, and carbohydrate we should eat.

Another reason why macronutrient intake is such a controversial topic is that a lot of dietary advice isn’t rooted in an evolutionary understanding of human nutrition. Let’s take public dietary guidelines for example. For decades, the idea that we should all eat a grain-based, low-fat diet has been ingrained in the public’s mind through food pyramids, public health campaigns, and commercials for fat-reduced food. This has led many people to think that this type of diet is the “natural” human diet. From an evolutionary perspective, this notion makes little sense…

Through the lens of evolution

If we expand our perspective beyond the modern age and into our evolutionary past, it quickly becomes clear that we miss out on huge chunks of the nutritional puzzle if we only focus on what’s been going on in the world of nutrition for the last century or so. For 99.5% of the evolutionary history of our genus, Homo, we lived as hunter-gatherers, and during this time, most of the foods that now make up the typical Western diet, such as grains, refined vegetable oils, and dairy, were not routinely eaten by any humans.

All of this doesn’t mean that we should necessarily avoid all of the foods that came into the human diet after the Agricultural Revolution; it just means that we should flip our focus. Instead of using the Modern Age as our starting point for looking at human nutrition, we might want to turn the clock back, start at “the beginning”, and study the evolutionary dietary road that led us to where we are today.

So, you might ask, how far back should we go? To really get a grasp of how our bodies evolved and what types of foods we’re best adapted to eat, we have to go back and look at all of the known stages in our evolutionary journey. That said, from the perspective of diet, it’s clearly the Paleolithic era and the diets consumed by members of our genus (in particular Homo sapiens sapiens) that are most important to keep in mind.

Although proponents of plant-based diets will often tell you otherwise, there’s no doubt that animal source food was an important part of the diet of our Paleolithic ancestors (1). Several lines of evidence show that animal source foods started becoming an increasingly important part of the hominin diet starting about 2.5 million years ago; a dietary shift that set the stage for the rapid growth of the large, complex brain of Homo erectus and other species that belong to the genus Homo (2, 3, 4).

In a paper from 2006, Boyd Eaton suggests that behaviourally-modern humans in East Africa 100-50 x 10(3) years ago obtained about 35% of their dietary energy from fats, 35% from carbohydrates, and 30% from protein, which is a very different macronutrient breakdown than what is considered “normal” today (5).

Following our species’ migration out of Africa approximately 70.000 years ago, humans started to settle down in different habitats around the world, something that resulted in the adoption of new and different dietary patterns. Hunter-gatherers who ventured into northern areas of the world (tundra and northern coniferous forests) typically ended up eating diets that contained less carbohydrate than hunter-gatherers living in desert and tropical grasslands (6).

There’s a lot of debate regarding the macronutrient distribution of preagricultural human diets, and the aforementioned macronutrient estimates have later been put into question by other researchers. What we do know for sure is that hunter-gatherer diets generally were higher in protein and lower in carbohydrate than the typical diet consumed in industrialized nations today. This statement is supported by several lines of evidence (7, 8), including an analysis of subsistence data from 229 worldwide hunter-gatherer societies which show that the most plausible percentages of total energy from the three macronutrients would be 19–35% for protein, 22–40% for carbohydrate, and 28–58% for fat (8). It would have been difficult, if no impossible, for Paleolithic hunter-gatherers to eat as much starch and sugar as most people do today, because they didn’t eat grains, at least not in large quantities, or processed food.

Preagricultural human diets are often classified as low-carbohydrate, high-protein diets, as they tend to be lower in carbohydrate and markedly higher in protein than modern diets. However, when we take into account the fact that we lived as hunter-gatherers throughout the vast majority of our genus’ evolutionary history, it becomes clear that it’s more accurate to label the typical macronutrient ratio of hunter-gatherer diets as the “baseline”, and a diet that contains 50-60% carbohydrate and 10-15% protein as a high-carbohydrate, low-protein diet.

Should we let the macronutrient ratio of preagricultural human diets guide the planning of our modern diets?

Just because hunter-gatherers typically eat/ate a diet that is relatively high in protein and low in carbohydrate (but hign in fiber) doesn’t immediately lead to the conclusion that this is the way to go for optimal health. First of all, as previously mentioned, some traditional people have maintained very good health while eating diets with a macronutrient distribution that falls outside of the hunter-gatherer “norm”. Secondly, we have to consider the fact that we don’t have access to the same foods as our primal forebears, and that a lot of people these days adhere to exercise regimens that differ markedly from Paleolithic physical activity patterns.

That said, as everyone in the ancestral health community knows, it’s always wise to consider the evolutionary evidence when we go about planning our modern diets. When we combine an evolutionary template with modern nutritional science, it becomes clear that the dietary pattern of our ancient ancestors serves as a very good model for designing a healthy, well-balanced diet in the 21st century.

Over the years I’ve written several articles in which I’ve taken an in-depth look at what the scientific research tells us about how much protein, carbohydrate, and fat we should consume. Here are some of the key takeaways from these articles:

  • The estimated macronutrient values of hunter-gatherer diets match well with what you get from a diet that contains a balanced proportion of animal source foods, fruits, vegetables, nuts, healthy fats, etc.
  • The average Joe eats way too much bread, pasta, breakfast cereals, pastries, and other grain-based foods and would probably benefit greatly from replacing some of these foods (in particular the ones that primarily contain refined grains) with more nutrient dense foods such as grass-fed meat, eggs, fish, and vegetables. When you don’t eat a lot of grains and processed food, it’s difficult to derive more than approximately 40-50% of your energy from carbohydrate, unless you eat tuberous root vegetables and/or sugary fruits all day long.
  • Protein has a potent effect on thermogenesis and satiety, and studies have shows that “high-protein” diets (>20%) are effective in the prevention and treatment of a range of health problems, in particular metabolic disorders and obesity (3) . This doesn’t mean that you have to eat a lot of protein, however, there is little doubt that there are many health benefits associated with a protein intake that is higher than the average intake of approximately 15% (of total calories) in the U.S. today.
  • Public dietary guidelines in the U.S. and most other industrialized nations advocate that people should derive about 45-65% (the exact number differs from country to country) of their calories from carbohydrate. This idea, that we should all eat a diet that is high in carbohydrate, lacks proper scientific support. A growing amount of scientific data suggests that a lot of people, in particular those who are overweight and/or insulin resistant, benefit from adopting a diet that contains somewhat less carbohydrate than this (9, 10, 11). That said, it’s important not to go too low either, as a diet that is very low in carbohydrate often contains less than optimal amounts of fermentable fiber and can compromise an individual’s ability to maintain high levels of physical activity.

The macronutrient ratio doesn’t necessarily tell us that much about the healthfulness of the diet

The macronutrient distribution of a diet merely gives us a broad overview of what the diet consists of. To really be able to design a healthy diet we also have to consider fatty acid composition, indigestible vs. digestible carbohydrates, types of carbohydrates, food choices, food quality, etc. Personally, I think there is too much focus on macronutrient intake in the health & fitness community and too little focus on the previously mentioned factors. The fact that traditional people around the world have thrived on diets with very different macronutrient ratios further highlights the importance of looking at the bigger picture of things.

What is especially important to mention is that hunter-gatherers typically consume a lot more fiber than we do today, in large part because uncultivated fruits and vegetables are more fibrous than domesticated versions. This has important implications for the macronutrient composition of the diet, as indigestible (to the human host) carbohydrates are fermented by gut bacteria in the colon to produce short-chain fatty acids, meaning that these fermentable carbohydrates actually provide energy in the form of fats. This further highlights the discrepancy between the carbohydrate content of “modern diets” and hunter-gatherer diets; a discrepancy characterized by a markedly lower net carbohydrate intake among hunter-gatherers.

My general recommendations

  • Protein: Eat moderate amounts of high-quality protein at every meal. Most people, particularly those who want to lose weight and/or gain muscle, would benefit from getting at least >20% of their total calories from protein. Homo sapiens, as well as many other animal species, have evolved a strong appetite for protein. If you eat a well-balanced diet, are in good health, and know how to listen to the signals your body is sending you, your appetite should naturally steer you towards an adequate intake of protein. Stick to grass-fed, organic, and/or wild animal products whenever possible.
  • Carbohydrate: Eat plenty of plant foods that are rich in fermentable fibers (e.g, onions, leeks). Adjust your intake of simple sugars and starch according to your physical activity levels. Athletes who perform a lot of anaerobic exercise typically require quite a bit of starch in their diet to perform optimally, whereas sedentary individuals – particularly those who are insulin resistant and/or overweight – often do best on a diet that is lower in starchy foods, particularly bread, pasta, breakfast cereals, and the like. Good sources of starch includes foods such as sweet potatoes, yams, and brown rice. A carbohydrate intake of 20-45% (of total daily calories) is a good fit for most people.
  • Fat: Include healthy fats in every meal. Foods such as avocados, eggs, salmon, and olives are superior to non-paleo foods such as cream, GHEE, cheese, butter, and bacon.

Picture: Creative Commons picture by bigbrand, Some rights reserved.

Comments

  1. Great article! Back to the basics!

    Another way to look at food is to divide it up not by macronutrient composition but by type during our species’ demographic transition.

    Forager/Agricultural/Post Industrial

    I don’t think it’s necessary to be so strict on the macronutrient composition anymore unless of course there is an underlying condition (eg diabetes) or there is a body composition end goal (eg fat loss).

    Delving deeper into ethnographic evidence, one realizes that even within foragers of the same biome, macronutrient composition varies according to season and luck. Most prefer meat, but end up with plant based fall back foods most of the time.

    Biochemically, I’m more inclined to think that it’s the acellularity and hence the macronutrient availability of the particular food that causes macronutrient imbalance. Ian spreadbury drew our attention to carbohydrate availability of flours and refined sugars being a mismatch and showing evidence of how that affect gut microbiota. In the same vein, fats and protein can be refined and ingested in highly processed forms and are definitely not what our bodies have evolved to cope with.

    Hence back to my original point.

    Breaking up food types into:
    Forager/agricultural/post-industrial types.

    Cutting out post industrial food types would eliminate IMO 80% of gross diseases affecting healthy common people regardless of ethnicity.

    Cutting out agricultural foods will be better for individuals who are a few generations downstream from forager populations (eg. Native Americans, Inuit and Australian aborigines). Of course certain individuals from populations with a long history of agriculture should also avoid dairy if it was never a big part of their ancestral diets (eg. Han Chinese).

    Ancestry is important. There’s no once size fit all solution for diet (except of course, cutting out post industrial goods).

    • Good points, Sam!

      I agree with a lot of what you’re saying. That said, I generally have a more conservative view than you, in the sense that I prefer to stick more closely to the preagricultural dietary template.

      As I’ve touched on before on the blog, I don’t think avoiding all grains is necessarily the way to go for everyone. I eat some grains myself, in large part because they help fuel my strength training sessions and provide fermentable fiber. That said, I definitely don’t think it’s a good idea to eat a diet that is very high in breakfast cereals, pasta, bread, and the like, regardless of recent ancestry. I prefer to stick with fruits and veggies most of the time.

      As for dairy, it has become increasingly clear to me over the years that a high intake of dairy foods may induce a range of adverse health effects, many of which you rarely see mentioned on ancestral health blogs. I’ll likely touch on some of these problems in a future article. Hints: Dairy foods have a less than optimal fatty acid composition, contain peptides with opioid-like activities, and may induce a suboptimal satiety response. Also, the metabolism of lactose could trigger some unfavorable health effects. In other words, both the carbs, fats, and proteins found in dairy products may be problematic. Caveats: Not all dairy foods are equally unhealthy and inter-individual differences in ancestry, microbiome composition, etc. do matter.

      • I do think that we actually have a broader spectrum of “survival” than other animals, and such feature is probably one of the keys of our success. However, I’m pretty much sure that there’s a shortcoming in observational evidence if took alone…we overlook the continuity in the virtual health curve. If we look at some traditional populations, we can be amazed by the comparison between a sub-optimal level and the average american Joe. I live in Italy, a place that many american researchers depict as the healthy country. Far from the truth, if you look at the evidence and data you shiver, but it’s nothing compared to the american nightmare. We evolved to achieve a fisical fitness that allowed us to become amazing hunters and flesh was up to 80% of our diet as norm. You can go down on meat and increase plant food, but there’s a constraint given by the expensive tissues theory by Aiello & co. And by the comparative physiology between us and the other animals. The more you rely on plant food, the more you should be equipped for that, but the more complex digestive tract and metabolic patway you should have…in poor words, our brain should shrink back and we should go back to chimps. There’s a physiological lower limit for nutrient intake that should come from animal stuff. If you look at the tables by Kaplan, the least meat eater tribe is the GWI tribe, with an average of 300 gr in a day! If you are a peasant, you barely need to be able to raise your crop without a great fitness proper of hunter gatherers and if you don’t raise wheat and eat some fish like Okinawas, you may be RELATIVELY healthy compared to OUR bad standard, but what is the norm for a pure hunter gatherers. Ache men becomes more able to hunt in elderly age for example. But to hunt such variety of wildgame it takes much more than a not bad lipidic profile or insulin sensitivity. We have to add that peasants need more carbs to replace glycogen after the lactacid activity, thus it is reasonable that also orthoculturalists may do good with more (cellular) carbs. But on average, fat is a better fuel for aerobic activities and we as humans seem to be much more prone to burn it as clean fuel instead of glucose.

    • Very good point about the cellularity of food. The paper by Spreadbury is one if my favourites. As he pointed out as well, concentrated carbs are more harmful than concentrated forms of proteins and fat, though it’s not advisable to abuse of such sources as well. However, the other major issue about grains are the prolamins, there are thousands forms of them, though gliadin is the most studied and most probably the most problematic. Gliadin triggers leaky gut in everyone (Hollow 2015) and normal control group exposed to gliadin for a while show gut even leakier than celiacs in remission group.. and we can’t know whether we are going to have adverse consequences from that. The more you are exposed to leaky gut, the more bad stuff (LPS etc..) can enter into your bloodstream and wreak havoc. ATIs and WGA (that seem to be only partially deactivated by cooking) are villains as well, binding to TLR4 receptors. Aside from that, though I’m a science “geek”, I learned to observe as well. When you eat flesh, you are strong and muscolar, there’s no way that a bodybuilder or powerlifter can thrive on a true vegetarian diet. Many influent paleo bloggers come from vegetarianism and veganism but they tried on their skin how proportionally related meat is with fitness and strenght. Look at asian populations, they are much smaller and weaker than us. I played to took a sample of many chinese and korean people (I swear, in the place where I work I see thousands of them in a week).
      I can easily say that 90% of them are sarcopenic and have curved legs like a bow, typical of nutrient deficiencies. And they are not starving since they can afford luxury goods. Instead, russians who rely on meat, have big bones and muscles, though processed food make them get fat as well. Then look at Maasai and Samburu warriors. They are tall because of the pumped IGF-1 from dairy proteins, but they are thin and their grip strenght is lower than the average americans. Then take the Ache tribe, who rely on wildgame for 70% of their diet. They are able to kill a prey shooting an arrow from distance in their elderly age with a strenght and precision better than younger guys. They are a good example of the granny and granpa theory for our species. Folks, the lesson is mixing science with observations and instinct, science alone make you blind, observation alone confounds you, instinct alone is good in nature, but their mix is the most valuable way to go. How do I feel? Strong, lean and muscular, or flabby, fatty and weak, despite of my blood markers?

      • The last thing I forgot, health is about diet but also lifestyle, stress and environment. We have to observe the effect of diet in our context. It’s for example possible that milk proteins have a certain impact on Maasai but it’s balanced on exercise, stress etc. and they may look very healthy if we compare them to us. But the question is: how dairy consumption may affect us in our context. If I pump IGF-1 constantly in a oncogenic environment, how will I end up? How do caseins and other hormones behave when I have a leaky gut provoked by gliadin, antibiotics, drugs, stress, etc? These are the questions about US…

  2. Good article. Thanks, Eirik. I was under the impression that cream, butter, cheese, and bacon are all more or less acceptable on a Paleo eating plan, provided one doesn’t have problems digesting dairy products. I do see, however, that avocados, eggs, salmon and olives might be healthier choices.

    • You touch on one of the biggest problems in the Paleo community today, IMO. A lot of people believe that cheese, GHEE, butter, etc. can “safely” be consumed in large quantities, even though these foods were obviously never eaten by our Paleolithic forebears. This isn’t surprising, as these foods historically have been promoted as healthy foods within the Paleo and low-carb community.

      What many authors and bloggers fail to mention is that these products have a very different nutrient composition from that of meat, fish, avocado, and other Paleo-approved sources of fat, and that a high intake of these evolutionarily novel foods can have a range of negative health effects. I touched on some of the problems with these foods in a recent article. I also have another piece on this topic in the works.

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