If paleo/primal advocates were strong rationalists, they would state the basic premise of the diet as follows:
“In the absence of evidence, the safest bet is to go with an ancestral diet.”
And I think it is difficult to argue with that. When the evidence is mixed on a topic, it seems natural to default to tradition. In general I think paleo/primal dieters consider non-ancestral foods guilty until proven innocent...as in, you would have to present them evidence that a non-ancestral food was harmless and healthy before they started eating it. Most people are asking “Why shouldn’t I eat X”, but within the paleo/primal philosophy, the burden of proof rests on the advocates of novel foods, since they are the one who deviate from the ancestral default. If you want to debate what exactly the ancestral default was, that is an entirely different can of worms...but it is easy to say which foods are certainly not ancestral.
By the way, carbohydrates are not criticized by the paleo movement. You’re thinking of Atkins. Fruits and tubers were part of our ancestral diet, and they are rich carbohydrate sources. They are encouraged in moderation.
The paleo criticism is that the modern diet’s primary source of calories is now grain, which was scarce in the ancestral environment. More dedicated paleo folks will also attack milk, legumes, and nightshade vegetables (in that order) but really the majority of complaints are directed at grain. Before agriculture, no one really ever ate it. After agriculture, the population boomed and people didn’t really have any better options other than grain. Now grain has been ingrained into our culture (pun intended) even though we have the resources to avoid it.
Anyway, there are three compelling pieces of evidence against grain: Lectin, Gluten, and Phytic Acid
1) Grain contains large amounts of phytic acid. Nuts contain more than wheat, but we don’t typically eat that many nuts per day. Chemists would call it a chelator, something that binds with ions. Dietitians would call it an anti-nutrient...it essentially stops your body from absorbing Zn, Fe, Ca, and Mg. Ruminants and grain-eating animals have evolved mechanisms to break it down, but humans have not.
2) Lectin is a natural pesticide which irritates gut linings. Over time, it causes leptin resistance...which contributes to unhealthy fat storage patterns and other metabolic disorders like diabetes.
3) While the gluten free craze is a bit out of hand, there is increasing evidence for a gluten sensitivity spectrum. Not everyone is a celiac, but a substantial proportion of the population experiences some amount of gut inflammation via gluten.
Add to these three things the notion that grains make it easy to consume large numbers of calories and can cause sudden spikes in insulin, and I think you have a pretty good idea of why the paleo/primal diet discourages extensive grain consumption. It’s really more about toxin and anti-nutrient avoidance than it is about carbohydrate vs fat as a calorie source—although it is generally agreed in these circles that modern diets are a bit carb heavy.
When the evidence is mixed on a topic, it seems natural to default to tradition.
I don’t think you mean “tradition” in the usual sense here, given that the paleo diet is a (putatively) scientific reconstruction rather than a traditional practice (i.e. one handed down through generations).
If paleo/primal advocates were strong rationalists, they would state the basic premise of the diet as follows:
“In the absence of evidence, the safest bet is to go with an ancestral diet.”
And I think it is difficult to argue with that. When the evidence is mixed on a topic, it seems natural to default to tradition. In general I think paleo/primal dieters consider non-ancestral foods guilty until proven innocent...as in, you would have to present them evidence that a non-ancestral food was harmless and healthy before they started eating it. Most people are asking “Why shouldn’t I eat X”, but within the paleo/primal philosophy, the burden of proof rests on the advocates of novel foods, since they are the one who deviate from the ancestral default. If you want to debate what exactly the ancestral default was, that is an entirely different can of worms...but it is easy to say which foods are certainly not ancestral.
By the way, carbohydrates are not criticized by the paleo movement. You’re thinking of Atkins. Fruits and tubers were part of our ancestral diet, and they are rich carbohydrate sources. They are encouraged in moderation.
The paleo criticism is that the modern diet’s primary source of calories is now grain, which was scarce in the ancestral environment. More dedicated paleo folks will also attack milk, legumes, and nightshade vegetables (in that order) but really the majority of complaints are directed at grain. Before agriculture, no one really ever ate it. After agriculture, the population boomed and people didn’t really have any better options other than grain. Now grain has been ingrained into our culture (pun intended) even though we have the resources to avoid it.
Anyway, there are three compelling pieces of evidence against grain: Lectin, Gluten, and Phytic Acid
1) Grain contains large amounts of phytic acid. Nuts contain more than wheat, but we don’t typically eat that many nuts per day. Chemists would call it a chelator, something that binds with ions. Dietitians would call it an anti-nutrient...it essentially stops your body from absorbing Zn, Fe, Ca, and Mg. Ruminants and grain-eating animals have evolved mechanisms to break it down, but humans have not.
2) Lectin is a natural pesticide which irritates gut linings. Over time, it causes leptin resistance...which contributes to unhealthy fat storage patterns and other metabolic disorders like diabetes.
3) While the gluten free craze is a bit out of hand, there is increasing evidence for a gluten sensitivity spectrum. Not everyone is a celiac, but a substantial proportion of the population experiences some amount of gut inflammation via gluten.
Add to these three things the notion that grains make it easy to consume large numbers of calories and can cause sudden spikes in insulin, and I think you have a pretty good idea of why the paleo/primal diet discourages extensive grain consumption. It’s really more about toxin and anti-nutrient avoidance than it is about carbohydrate vs fat as a calorie source—although it is generally agreed in these circles that modern diets are a bit carb heavy.
I don’t think you mean “tradition” in the usual sense here, given that the paleo diet is a (putatively) scientific reconstruction rather than a traditional practice (i.e. one handed down through generations).