The ketogenic diet has become, in recent years, one of the most searched diets online and has become one of the most popularly used diets for weight-loss. Coming hot on the heels of the paleo diet explosion of recent years, these types of diets have firmly embedded themselves in the popular consciousness. While there is no singular diet that works best for everyone, and most diets that work are due more to adherence and compliance than the diets themselves. It’s fair to say that the evidence shows that paleo and keto diets are effective for weight-loss and the improvement of markers of health.
But, this article isn’t about the relative merits of different diets! It’s about whether plant-based proteins are appropriate for use on ketogenic and Paleo diets.
What are Ketosis and Ketogenic Diets Anyway?
Ketogenic diets elicit the state of ketosis. Ketosis is when the body produces ketone bodies, mainly from fats (and some amino acids) to use as an alternative fuel in times of fasting or drastic carbohydrate restriction.
When stored carbohydrate (glycogen) reserves aren’t sufficient to supply the glucose necessary to fuel the brain and central nervous system, an alternative fuel source is needed. Ketones (especially beta-hydroxybutyrate) are created in the liver to supply the necessary fuel to the body and brain.
A ketogenic diet is a form of very low-carb, high-fat, low-to-moderate protein diet.
Originally developed as a treatment for childhood epilepsy beginning nearly a century ago, keto and other low-carb, high-fat diets are now being studied for their potential use for Alzheimer’s Disease1, Parkinson’s Disease2, Autism3, 4, Cancer5-7, and Diabetes and Obesity8-16.
Ketogenic diets typically require that you eat almost no carbohydrate and very high levels of fat. This equates to around 4-parts fat to 1-part protein and carbohydrate (a 4:1 protocol)17, but ketosis can be achieved with a little more protein and carbohydrate, and less fat, if you use a specific type of oil called MCT oil (medium chain triglycerides)18, 19 which is commonly available as a supplement.
Plant-Based Proteins and Ketogenic Diet
The main concern with using plant-based proteins in a ketogenic diet is that many of them are proportionately lower in protein, and subsequently higher in carbohydrate, than the common standard of whey protein concentrate (isolates are even higher in protein and lower in carbohydrate.)
For example, hemp proteins are typically around 25% carbohydrate, and rice protein isolates are around 10% carbohydrate (by weight). It’s important to remember though that more important than the percentage of carbohydrate in food is the total amount you are taking in per day and how that compares to your ability to be in ketosis. There is a really wide range of carb intakes that can allow people to reach ketosis! But overall, you should choose a supplement higher in protein and lowest in carbohydrate if following a ketogenic diet.
I want to make my case here for my pick for plant-based proteins for keto, a high-quality pea protein isolate, as these can contain up to 90% protein by weight with around 2% carbohydrate. And before you ask… don’t worry about whether pea protein isolate is complete. While many plant proteins aren’t complete (i.e. they lack sufficient amounts of one or more of the nine essential amino acids), if you are getting enough protein overall, you need not worry too much about whether one of your protein sources differs marginally in amino acid content (20, 21).
That said, high-quality pea protein isolates exceed all amino acid requirements for the healthy functioning of the human body as defined by the World Health Organisation (except for methionine and cysteine in which it is only fractionally under the recommended amount). This amino acid profile also compares very favorably with the recommended amino acid pattern proposed by the Institute of Medicine of the United States National Institutes of Health22.
Because of its very high protein content and low carbohydrate content, pea protein isolate is a favorite of many keto dieters. It’s also considered to be a very satiating protein that anecdotally (probably because of its gelling properties) helps promote greater feelings of fullness and satisfaction than whey protein.
Plant-Based Proteins and Paleo Diets
Paleo is a dietary approach that seeks to (at least partially) emulate that of our hunter-gatherer ancestors. While often claimed to be a low-carbohydrate diet like keto, it’s not necessarily low-carb. The diet can contain considerable carbohydrate from tubers like sweet potatoes, potatoes, yams, and berries and fruit (although some paleo followers remove some or all of these too.) It excludes all grains, legumes, and dairy typically.
The biggest concern for followers of paleo diets is the presence of anti-nutrients in plant proteins. These can include phytic acid (which inhibits uptake of various minerals), saponins (which can cause gastric upset), and trypsin inhibitors (which reduce protein digestion). Overall, for most people, there’s little concern that eating some of these are going to cause any problem at all.
They are present in many foods, and people eat them regularly without any cause for concern. But, if this is a concern (and it will be if you’re a paleophile!), many processes help to markedly reduce the levels of phytic acid in legumes and grains. Soaking in an acidic medium (such as lime juice), cooking, and sprouting are all methods that have been shown to reduce the presence of anti-nutrients.
Nowadays, high-quality pea protein isolates are processed using a low-heat, enzymatic isolation process which effectively removes almost all the phytate, lectins, saponins, and trypsin inhibitors.
As you can see in the table below, the functional properties of the gold standard of plant protein, isolated golden pea protein, are quite different to whole legumes and to the commonly used vegan protein, soy protein isolate, with between 1/60th and 1/100th of the phytate content.
So, despite it being derived from a legume, pea protein isolate has become a favorite of many in the paleo and primal community, especially if they are intolerant to either lactose or one of the dairy proteins (whey or casein).
|Antinutritional Factors||Pea Protein Isolate||Pea (seed)||Soybean||Soy Protein Isolate|
|Trypsin inhibitor (TIA/g protein)||2.5||8.1||101||73.6|
|Lectins (HU/mg protein)||Approx. 0.2||37.1||3.2||0|
|Tannins (mg cat eq/g protein)||None detected||0.96||0.8||0.25|
|Phytates (mg/g protein)||1.2||101.1||89.6||62.7|
Is Pea Protein Well Absorbed and Used in the Body?
It is often claimed that pea protein isn’t well absorbed. This is a myth. In fact, pea protein exhibits absorption rates of over 89%23, and is, therefore, an extremely absorbable protein type.
It is also functionally beneficial. In an evaluation of pea protein isolate vs. whey protein, both protein types of protein elicited nearly identical increases in muscle thickness when compared with placebo24.
Pea protein is, in my opinion, the best plant-based option for people on keto and paleo diets due to its higher protein content, extremely low carbohydrate content, and low anti-nutrient levels. It’s beneficial for muscle growth when compared directly to whey protein and offers a viable alternative to animal-derived proteins for vegans, vegetarians, others interested in plant-based diets, and for those not tolerant to dairy or other proteins.
Cliff Harvey is a co-founder of Nuzest, a supplement company that makes a pea protein isolate Clean Lean Protein.
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