Stripped down to essentials, the idea of seasonal eating is that we should be eating fresh produce at the time of year that it would naturally be ready for harvest but avoiding large amounts of such foods at other times.
Clearly, genetics will play a role in this. Depending on which part of the World your DNA mostly derives from, your body may be expecting changes in diet at different times of the year. It is highly likely that someone with Maori genes from New Zealand will have a body expecting different inputs than someone with Inuit genes from Alaska.
Seasonal Eating and Genetics
These differences are not trivial. Eating in a way that ignores this is liable to lead to a body maladjusted to the input of nutrients. Essentially, our bodies will be expecting a much higher input of carbohydrates at a time of year when fruits and vegetables are in abundance in the environment and, conversely, a much higher input of protein and fat in seasons when fruits and vegetables would not historically have been so readily available.
In my case, for example, given my Northern European genetic make-up, my body would readily enjoy and store carbohydrates during the months of June through October whilst expecting protein and fat in the remaining months of the year. The body will happily store fats during the later summer and autumn in preparation for more challenging times to come during the winter and into spring. On the other hand, if my ancestral roots were from the regions we now called Thailand or Puerto Rico, my body would be primed to act in a very different way.
Feast and Famine
Essentially, this seasonal mechanism was built into us through thousands of iterations of survival in the relevant environment going back through evolution. In my case, it would have been physiologically wise to store fat in preparation for the predications of winter to come. Our problem is that in the modern world we have a readily available and continuous supply of fruits and vegetables, even if they are no at all seasonal in the immediate environment. This leads to our bodies continuing to receive the once seasonally related message to be storing fat throughout the year. The upshot of this is that although we will be apparently eating healthily, we will go on gaining weight.
The famine that we prepare for never follows the feast, hence we just go on storing more and more fat awaiting the challenges that never come. A mechanism that was extremely useful for countless millennia is now suddenly playing a detrimental role in our current, somewhat unnatural, situation.
Seasonal eating attempts to address this problem.
Ancestrally Appropriate Seasonal Eating
Our ancestor’s diet tended to vary widely. Factors such as geographical location, the availability of food in the immediate environment, and the local culture all played a role in dictating what food would be consumed and when. This variability would have affected our ancestors down to the macronutrient levels. The amount of fat, protein and carbohydrate consumed would have been fundamentally affected by the above-named factors. In general, fats and proteins would have been more available through the winter and spring whilst carbohydrates more common in spring and summer.
As we know, animal foods tend to be the most nutrient-dense that we have available to us. This is as true today as it was for our primitive ancestors. This holds true even if we go back as far as our hominid predecessors. Many of the nutrients available in animal products not only play a crucial role in our health but also are very difficult to get from any other source.
We have examined some of these essential nutrients in previous blogs but to give examples of a few of the more fundamental we could point to vitamin B12, heme iron, choline, preformed vitamin A and, most obvious of all, good-quality, bio-available and complete protein.
An interesting factor comes into the equation at this point. As pointed out by both Kris Kresser (1) and Paul Saladino (2), our ancestors would have eaten animals nose-to-tail. For some strange reason, in recent decades we have tended to increasingly stick to muscle meat alone. Even the strongest of animal-based food advocates tend to focus almost exclusively on muscle meat, particularly steaks in one form or another. Our ancestors would have been a lot less picky, and wisely so. There are many vital nutrients that are readily available in organs, bones and tissue that are not found in abundance in muscle meat.
It’s kinda odd to listen to some of the folks on YouTube expressing disgust with liver and kidney although still propounding the benefits of animal-based diets. This is something of a sad reflection on the ‘sensitivity’ of modern humans. Personally, I am quite partial to beef-heart, beef and pork liver, and kidney (3). Bone broth, with its high quantities of vitamin A, K3 and other nutrients, is another favourite that is both easy to produce and very healthy (4).
Summer and Autumn: a time to fatten up
The annual cycle that our bodies are so deeply embedded within provides an abundance of fresh carbohydrates at certain times of year whilst barely any such foodstuffs at others. In the UK for example, the first fruits start to appear in mid to late May. Although we are experiencing a particularly cold spring this year, tayberries should be appearing soon. They will last for a few weeks and then be closely followed by strawberries and gooseberries. By the time they have finished, towards the end of June, we normally have an abundance of fruits and vegetable readily and easily available until the last weeks of October.
The ancient predecessors of these berries, fruits and vegetables would have been gathered by our ancestors and, no doubt enjoyed enormously. Late spring into the summer, and the whole of autumn, would have been a time to enjoy these fruits of the land. Our bodies would have used the opportunity to put on weight in preparation for the challenges of winter when fruits and vegetables would have been scarce or completely non-existent.
This would have gone on for thousands, nay millions, of years. Our bodies would have evolved to take advantage of this seasonal availability of food. Excess fructose would have been converted to fat stores which, in turn, would have been used up during the long and hard winter. The mechanism of being able to store fat would have had a huge evolutionary advantage.
Seasonal Eating and why we store Fat
Unfortunately, this same mechanism can now often work against us. The high-fructose foods that were previously only available for a few months are now stocked in abundance in supermarkets 365 days a year. Our bodies are preparing themselves for the challenges of winter that never come. We go on storing more and more fat but never experience a season when the fat is burned off.
In a sense, our bodies are doing exactly what they are supposed to do, but we are living so unnaturally that we never balance the equation. We take in huge amounts of carbohydrate, often in the form of fructose, responding to ancient ancestral patterns within us. Unlike our ancestors though, we never give our bodies the chance to use up the fats that it has stored through this process. The long, hard winter when our bodies would have relied on the fat it stored through summer and autumn never occurs. Instead of being well-adjusted, we just go on getter fatter and fatter in preparation for shortages that never come.
Living in sync with the seasons may well not only be the appropriate approach for humans but a driver of health in itself. The modern world, with its ability to divorce us from the seasons and rhythms that have ruled our lives for millions of years, separates us from the natural cycles of light and food that our bodies utilise to maintain optimal function. There are times of the year when it may be perfectly appropriate to consume quantities of fresh fruit and vegetables. There are others when our bodies should no longer be relying on such fat inducing produce. Essentially, there is not one ‘diet’ that is optimal 365 days a year. Instead, there is an ongoing relationship to the foods that our bodies need in order to live in a harmonious relationship with our physiology and our planet.