Some things seem so obvious no amount of research or inquiry should be necessary to establish veracity. Things Simply ARE. The notion that fat makes one fat is a prime example. Consider the balanced chemical equation for the formation of water from hydrogen and oxygen:
H2 + 1/2O2= H2O, hydrogen and oxygen on one side, same thing on the other. Linear, first order logic like this permeates our world and serves us sufficiently in most situations…but not all. Consider the notion that fat makes you fat. Fat+People=FatPeople. It makes sense…fat on one side of the equation (food)= fat on the other side of the equation (people). Unless you’ve had your head at the bottom of a bag of Heart Healthy SnackWells you likely know better than that…but it makes SO MUCH sense!
In the 1960’s a theory was put forward to explain our tendency to get fat and this theory has elements of the flawed first order thinking described above. In fact many interrelated topics concerning fat gain and health fall down because of this reasoning. The catchy name was “The Thrifty Gene” Hypothesis. In this scenario, the collective “WE” are the unwitting victims of gremlin like genes that curse us with a tendency towards the cherubic because our ancestors had access to sporadic food sources and thus the folks who could gorge when the gett’n was good faired better when victuals were scarce. Why? Because, some could STORE fat more effectively than others, or so the theory goes. In more carnal terms, some folks were chubby enough to survive long enough to procreate. At first blush this makes a lot of sense and certainly we have the capacity to store energy in the forms of glycogen, protein and fat but is this Thrifty Gene notion TRUE? Well…no. Before I get into why it’s not true I just want to make clear that the thrifty gene hypothesis is predicated on the notion that periodic starvation and LACK of food is the reason why our affluent (most “authorities” point to fat as the problem) lifestyle leads us to our chubby condition.
Thrifty Gene Debunking Part 1-Cordain Speaks!
Prof. Loren Cordain wrote a communication to DR. Gerald M. Reaven MD regarding details of the mechanisms underlying insulin resistance and it’s evolutionary significance. You can read that full exchange here but I’d mainly like to illustrate Cordain’s point that starvation was rare in hunter gatherers was and continues to be largely ignored. Prof. Cordain makes the point that the archeological evidence and ethnographic records suggest that hunter-gatherers experienced little starvation, especially as compared to agriculturalists. Now this is a central feature of the Thrifty Gene hypothesis which is a guiding principle of modern metabolism research…and Dr. Reaven felt that debate on the DETAILS of why insulin resistance exists (mechanisms) was unimportant compared to simply agreeing that insulin resistance was “Once evolutionary useful…” Dr. Reaven is a hell of a researcher but the WHOLE premise of the Thrifty Gene hypothesis is that our ancestors faced frequent starvation and the only people to survive were those who had the most energy efficient genes. If the premise of frequent starvation is WRONG then our researchers are trying to interpret data and make sense of metabolic derangement with a broken model. This is a painfully common theme in research concerning why we get fat. Speaking of which:
Thrifty Gene Debunking Part 2-Devany tells us why we get fat.
Prof. Arthur Devany wrote a BEEFY paper some time ago with the provocative title: Why We Get Fat. It’s a great paper but it’s thick and fairly technical…muscle through it and get what you can from it anyway. What I want to highlight from the paper are the models of energy consumption and expenditure that show humans are wired to live at caloric excess. There were certainly periods of hunger, however these periods are relatively short and the energy reserves necessary to carry humans through lean times is achieved by the 9-13% body fat typical of hunter-gatherers.
Thrifty Gene Debunking Part 3-Dr. Michael Eades
Just a few days ago the always right on Dr. Michael Eades posted a fantastic piece comparing the Ansel Keys starvation study to the Yudkin low Carb study. The reason for this post was to make firm his position that “A calorie is not a calorie”. Apparently Dr. Eades has taken some heat from folks who contend total calories are the most important component of fat gain and health issues, while the good Dr. contends food quality is of greater importance. In this comparison Dr. Eades drew upon two historically significant studies that compared the effects of approximately isocaloric diets with VASTLY different macronutrient ratios. Both contained similar amounts of protein but one had the bulk of calories coming from carbs, the other from fat. If, as some of Dr. Eades detractors put forward, a calorie is just a calorie, the health, energy and vitality of the subjects in the two tests should have been identical. Oh, But they are not equal! Calories matter however it appears composition matters more…but why? On a mechanistic level it is obvious that insulin plays a remarkable role in hunger, nutrient partitioning and general health. It is a bit off topic but interesting to note that the high carb group displayed symptoms consistent with nutrient deficiencies including essential fatty acids and vitamins. We observe no such problems in the low carb group. Recent research has demonstrated that low carb diets decrease the need for various nutrients including folate and omega 3 fatty acids as compared to a standard high carb diet. Interesting no? One might even make the case that the junkier the diet (higher in carbs) the more vitamins are necessary…and this is indeed what we observe.
Dr. Eades offers a phenomenal analysis of the two studies but I think it’s worth noting the low carb group is allowed ad-libitum access to food, yet theses folks consumed what is essentially a caloric restricted diet…but with none of the problems experienced by the high carb group. According to the Thrifty Gene hypothesis, if humans are given access to unrestricted food they SHOULD gorge well above maintenance levels because this is the only way our ancestors could have survived. What we observe however is if carbohydrate levels are relatively low while protein is moderate and fat intake is high satiety precludes weight gain. Said another way: It’s hard as hell to get fat on a low carb diet. Carbohydrate consumption is the underpinning of metabolic derangement which fuels additional hunger…. that leads to the vicious cycle of additional carb consumption.
Evolutionary biology is important for a framework to postulate questions and assess data relating to human health but what if we have our model wrong? A calorie is just a calorie and our genes are suspiciously thrifty…and the real reasons for disease go ignored because they do not fit our expectations. It’s time to either rethink our models or actually pay attention to our evidence!