I was motivated to do this post for a number of reasons. Firstly the Paleo Diet and its followers is gaining popularity akin to Justin Bieber and for similarly unfounded reason. I am also doing some work with the fine athletes at TAGG Crossfit in Sea Point and we know that the Paleo Diet is the default recommendation for crossfitters. Thirdly, I attended a fantastic talk by Dr Ross Tucker from Science of Sport during which he touched on the Paleo debate and Low Carbohydrate Diets that re-stimulated my annoyance in this area.
What is Paleo?
In essence it is a move toward a diet that our early ancestors followed. The Paleolithic Era, or Stone Age, extends from 2.5 million years ago up until about 10 000 years ago when the seeds of agriculture were planted. The argument is that our genetic development over this long period of time was tailored to that “common” diet and in the relatively short time since then we have not adapted genetically to a vastly different diet. Thus we are still better suited to follow Stone Mans lead:
|√ Grass-fed meats|
√ Fresh fruit and vegetables
√ Nuts and seeds
√ “Healthy” oils (Olive, walnut, flaxseed, macadamia, avocado, coconut)
|× Cereal grains|
× Legumes (including peanuts)
× Refined sugar
× Processed foods
× Refined vegetable oils
The main point that annoys me is the science behind this and the theorised proof.
It is hypothesized that the diet was one of fruit, vegetables, nuts, insects, wild meat and fish. It sounds like a time of abundance and good eating. In reality it is more likely that at any one time only one of these food groups would have been available to the hunter-gatherer. In addition the variation in diet from one part of the globe to the other was likely to have been stark, in the arctics a vast majority of food would have been from meat sources as opposed to the forest or savanna where plant foods would likely have made up most of the diet. The exact, or even close estimates of, dietary proportions are not available and to generalise would be poor science. I use the word “likely” repeatedly because ultimately we do not know, there are few records from early days and most of the story is pinned together by rock art and a little archaeology.
The genetic theory is thin too. While it is true that our genes have not changed much in the last 10 000 years this does not mean that the expression of these genes has not adapted. Epigenetics, the study of the expression of genes, teaches us that many of our genes are expressed according to the environment they are exposed to. As our environment is much changed from 10 000 years ago it is perfectly acceptable to assume that the expression of certain genes has changed and adapted. Although our genetic backbone is very similar to Paleo Man, they too are very similar to chimps but no one has recommended following a primate diet yet.
Another motivation one would hear from Paleo Punters is based on the fact that this time in history corresponded with a lack of chronic disease, thus it must be the diet that kept everyone fit, healthy and strong. This is purely observational, however, and attempting to define a fact from an observation is also poor science. There are any number of other factors that may have kept Mr Paleo “healthier”, if indeed he was. It is as scientifically sound to suggest that because he wore no shoes he was healthier, or the lack of toothpaste prevented disease. It could quite possibly be more realistic issues like more exercise and activity, less stress, exposure to sunlight, a shorter lifespan and an unrefined diet. Or how about a little of all of that??
Nonetheless all of this would not be relevant unless we as a society have recognised that the current diet is terrible and we need to turn back the clocks so to speak.
So is the current diet that bad?
Most of the “supporting” evidence points to the rise in obesity and chronic disease that now plagues the modernised world and all fingers are pointing to our diet. The recent progression in body size and disease kicked off mid way through the 1970’s at a time when authorities recommended a greater intake of carbohydrate and a reduction in fat. Research shows that the intake of carbs has increased since then with a slight reduction in fat intake. Interestingly, however, the same research shows that current levels of carbohydrate intake are about what they were at the turn of last century (it subsequently declined until the 70’s) when obesity and chronic disease were not common. There has also been an increase in fat intake and total energy over the last century with protein remaining fairly constant as far back as these records go. Which of these factors, if any, are to blame? Perhaps the distribution of these macronutrients in the diet has little effect one way or another when considering an entire population. Certain populations survive and thrive on 90+% carbohydrate, others on 80+% protein and fat. To generalise one way or another is, again, poor science.
There are few, if any, well constructed and well controlled trials that have tested these hypotheses by manipulating the macronutrient content of the diet to achieve health improvements. The closest we have is the 2008 DIRECT study published in the New England Journal of Medicine. While this was a much better quality study than many others that evaluated certain health outcomes between low fat, Mediterranean and low carb groups over two years, the results and conclusions have apparent holes. At the core is the wide variations in results, the relatively small weight loss (2-4 kg over 2 years!) and the poor adherence of the low carbohydrate group. The most significant finding was perhaps the much improved lipid (cholesterol) profile exhibited by the low carbohydrate group. The fact of the matter is that some people will respond to a low carbohydrate diet, as some will respond to a low fat or Mediterranean version. Generalising an approach would be, again, poor science.
The modern diet, however, does have many issues that cannot and should not be ignored. For fear of generalising I will state that high energy diets, added sugars (of many kinds) and refined plant oils are quite likely to be related to many health issues in certain populations. To boot, insufficient dietary intake of whole foods and poor dietary variation may contribute to deficiencies and poor health. There is also evidence that, while our genetic expression has changed, not everyone responds the same way, we are not all the same! Certain foods may be poorly tolerated by certain people and the proteins in grains, seeds and milk are possible issues. Some people may be suited to a diet without these while others may have the genetic expression to handle them.
For this reason the Paleo Diet is a good starting point and not because of the popular “science” behind it. The removal of possibly poorly tolerated foods might allow some people to feel or perform better and in addition a focus on foods that we know are beneficial (fruit, veg, lean meat, seafood, nuts) cannot be a bad thing. However this is not to say that grains and starches should be cut out by everyone, there is no proof that a low carb approach benefits everyone. In fact Cave Man is quite likely to have survived at times on roots and tubers, a perfect storage item of carbs. For sporting performance endurance athletes should never follow a low carb diet (a generalisation I know but evidence is overwhelming) but athletes of lower intensity sports may use this as an approach to suit their individual goals.
The modern lifestyle seems to a criminal that gets off quite light in the wake of the focus on diet. The advent of urbanisation (post World War 2/pre 1970’s) has bread a less active and lazier society without a reduction in total food intake. We walk less relying on cars, public transport and seated entertainment. We play less, we adventure less, we seek less. Everything is easy, accessible and at our fingertips, the same fingertips that are pointed at the modern diet as the root of evil. Some people have realised this and to maintain the theme of extremism some dangerous or misleading messages have filtered through; “3 minutes of maximal exercise per week is enough to live longer”, “40 minutes of strenuous exercise 3 times per week is needed to avoid heart disease”, “you must train at x % of your heart rate to prevent chronic illness”. We are motivated through fear, as is clear in any message popular media uses as a headline. We also have a fascination for directions and the use of values to measure our health and progress by, which is great in a way but nonsense in real life. Why not look to be as active as possible as often as possible. If you need to improve your health, do more. If you need to maintain, do the same, if you are over training or injured, do less.
And the same goes for your diet. From personal experience and research, I know that manipulating the carbohydrate content or fat content of a diet can bring about health gains and that what works for one person might not work for another. I know that there are certain populations (athletes, certain diseases) and personalities who benefit from serving sizes, food weight or volume, macronutrient distribution and frequency of eating where numbers and directions can work. For the general population and as a global message this is not practical, this is not real life. For that matter what is the general population?
A take home message:
Eat well, eat a little of all whole foods, avoid added fats and sugars, eat lots of vegetables, experiment with foods that work for you and enjoy your food. Oh and keep active!