At the other extreme, there are the vegans, who won't touch anything produced by an animal. At both extremes of the extremes, there are raw foodists. Raw animal products (no veg) on the one hand, and raw vegetables (no animal products) on the other. Meat vs. veg.
My impression is that the vegan camp is dominated by females, the meat camp is dominated by males. I personally know several youngish vegans, as well as people of my age who are ex-vegans, but I don't know any older vegans. My impression is that the majority don't maintain their veganism longer than several years.
There's no love lost between hardcore vegans and paleo people. Mars and Venus, anyone?
Yet they have a surprising amount in common, which perhaps has something to do with why they dislike each other so much.
For one thing, people from both sides, after they have followed their diet fairly strictly for some time, are seldom overweight. Both groups believe in eating food that has little or no processing. Many paleos (not all) and all vegans eat vegetables. Vegan raw foodists don't eat many, if any, grains, because they generally need to be cooked to become edible, so they have that in common with paleos too. Most dairy products don't feature high on the paleo menu, because they often contain a fair amount of carbohydrate, and because most paleos try to select the majority of their diet from foods that were available before man turned to agriculture and domestication of animals.
The big difference between these two camps is in the source of their protein. Both vegans and paleos derive at least some of their proteins, or to be more specific, amino acids, from animal sources. You're wondering if that is a typo, right? Well read on.
Contrary to what many non-vegetarians believe, there is no shortage of vegetable sources of protein. The issue is that, unlike meat, not all the building blocks of protein are available in vegetables. As the Vegetarian Resource Group explains it:
Protein is made up of amino acids, often described as its building blocks. We actually have a biological requirement for amino acids, not for protein. Humans cannot make nine of the twenty common amino acids, so these amino acids are considered to be essential. In other words, we must get these amino acids from our diets. We need all nine of these amino acids for our body to make protein.I was intrigued to see that That Paleo Guy describes the exact same thing from a paleo perspective as follows:
In the absence of animal-derived fat and protein from your diet, you[r] body can turn to its own human-animal sources. That is right - don't eat the fat and protein, and you will invariably begin to reduce your own levels at an accelerated rate. ...So whereas from the vegan perspective, they manufacture many of their own amino acids to supplement with those found in vegetables, the paleo camp derives theirs from meat sources alone. They think vegans are crazy to be doing it the hard way, since vegans essentially cannibalize themselves by breaking down their own stores to find the essential amino acids they are lacking.
... they are 'self-digesting' their own protein from lean body mass sources, and running quite nicely on the saturated animal fat being burned from their muffin top. This is a point so often missed by nutritionists, dietitians, doctors, researchers, etc... when people burn their own fat through their metabolic machinery, they are 'consuming' a high saturated fat 'diet', regardless of how low-fat a diet these professionals think they are prescribing.
Personally, I think it's rather neat that there are two completely opposite ways of arriving at the same point.
Whereas vegans would see that as a justification for not killing animals to sustain themselves, this is not a view I'm totally sold on. The fact that there seem to be so few long term vegans around makes me suspect that total veganism probably isn't the answer for optimal nutrition, and certainly not for me. It lends credibility to the paleo assertion that vegans eventually deplete their available stores of essential amino acids. This can cause health problems that can only be resolved by consuming some form of animal product, whether it be meat or dairy products, both of which contain all the essential amino acids.
I wonder if there is a third way. Could an acceptable variant for people who can't stomach meat be a largely vegetable-based diet that is supplemented by free range eggs instead?
The answer to that depends on the amount of carbohydrate being eaten with those vegetables, and the effect on insulin levels. Habitual insulin spikes in response to sugars in the system underlies all the diseases of modern civilization, to which vegetarians, by and large (admittedly a disparate group) have not been statistically less susceptible. This is why the paleo approach minimizes the consumption of carbohydrates.
I would be very interested to compare the levels of insulin resistance of people like Dr. Neal Barnard, a major proponent of a low fat calorie-restricted vegetarian diet, with those of paleo proponents like Gary Taubes and Mark Sisson. Maybe then we would find out if the two approaches can be reconciled in any way.