Theories are wonderful things. They allow us to say a whole range of things and sound very professorial when we do it.
"The theory is that we are designed to eat low carbs because for 100,000's of years, our cavemen ancestors ate a primarily meat and fat diet".
This is one of the founding principles behind low carb diets, specifically one like the Paleo diet.
It makes sense - right ? Unfortunately, we do not have that many caves with people in them, AND we are fresh out of dinosaurs, so it is difficult to prove this theory. But repeat this theory often enough to people, and they will begin to recite it as doctrine.
Now, before anyone thinks I am about to trounce all low carb diets, let me make full disclosure. I personally follow a low carb diet. I actually believe, from my reading of the literature and my personal experience, that low carb diets are THE solution to many people's health problems. So, the purpose of this discussion is NOT to shoot down Paleo diets and their kin. It is to make clear what the danger is, in relying on unproveable theories.
So, let's go back to our caves, where the lean mean six-pack wielding cave men (and women?) are telling stories about the silly looking Tyrannosaurus Rex they saw earlier in the day. What can we really learn from their lifestyle ?
Well, for one, they did not have exercise bikes in these caves (or at least, we have not found any amongst the fossils). They also did not do Pilates as far as we can tell. And finally, we found no evidence to date of them squatting 1000 pounds and then flexing in their mirrors. So, for one, IF we want to learn something from the cavemen, it is that we were clearly designed and selected genetically NOT to formally exercise !! Interestingly, no one ever mentions that. Now it is true that chasing down and killing those big dinosaurs required alot of running and shooting and jumping. If anything, we might be able to argue that high intensity physical activity (which is its own style of training) IS in our genes. But would someone, in either the low carb and hi carb camps, argue that we should NOT formally exercise because our great ancestors never did ?
What about the effect of such a diet on longevity? How healthy were the cavemen by the time they hit 50, 60 and more years of age? Well, as far as we can tell, until the modern era of medicine, people tended to die quite young (MUCH less than 60 years old). So, for all we know, a caveman diet might be great for us until we are 30 or 40, but becomes toxic to our bodies when we hit our midlife crisis (which back in cavemen days meant hanging out with the 20 year old cavegirls and riding around in a suped up cart on wheels). So, the theory sounds great. But when you think of all of the repercussions of being genetically selected out for living under caveman conditions, it actually makes you want to rethink trying to emulate their lifestyle. In other words, we would probably do better trying to break away from their habits and find a way to bend our genetics so that we will still be healthy when we are much older. THIS theory has as much validity as the one that says, "eat like cavemen".
Now, contrarily, I have heard speakers talk about the clear benefits of eating non-meat / non-dairy / non-fish / non-egg diets and how vegetarianism and veganism are, as their theory states, the way to counter all of the toxins that we eat on a regular basis. I have heard them describe various chemical reactions in our bodies that produce all kinds of nasty by-products when subjected to anything other than broccoli. To be clear, I think it is true that there are many benefits to eating lots of vegetables and fruits. And any healthy diet should include these items, in their most natural form (see my previous post). But meats and fish and eggs are not Satan's way of getting to our souls. One can eat a healthy diet and have great blood tests and great cardiovascular fitness while still eating a steak, salmon, eggs WITH the yolks, and a glass of milk. In fact, there are those who would benefit greatly from adding such foods to their diets to counteract their low Calcium, low Iron and low vitamins.
The way to know if a particular diet/lifestyle is better than another, is to formally compare them in a controlled study. Theories get disproved all the time when the actual experimentation is done. Many very smart people have had to retract their brilliant theories when the final data was analyzed and proved the exact opposite of the existing theory.
So be wary of theories. Be careful when a lecture on ANY topic spends 3/4 of an hour talking about the theory and then only mentions, in passing, a couple of studies with data that support this theory. When you have the winning horse, you do not need to describe all the reasons WHY it should win. You should be able to show a picture of it with the trophy, and then you can talk about anything else you want. In the same fashion, if someone wants to prove their theory about lifestyle and eating, let them start with all of the supporting research, THEN let them list the research that challenges their theory and THEN let them explain away these contrary data. THAT is an honest and professional way to address any topic.
Thanks for listening.