Nature follows seasons and cycles.
Days are longer in summer and shorter in winter.
It’s hotter in summer and colder in winter.
We are now coming to understand the myriad of processes in our body that are tied to a 24-hour circadian rhythm. Perhaps there could be a longer-term yearly cycle that our bodies are optimised for that it would be beneficial to understand.
These days our “seasonal” weight gain is driven by holidays like Christmas, Easter and Thanksgiving.
But before the creation of these artificial holiday “seasons”, humans got fatter in autumn in preparation for winter and leaner in spring coming into summer when we have the sun to keep us warm.
Like any good mother, Nature looks after our food requirements.
- In winter, there are less starchy and sugary carbohydrate-dominant foods and more fatty animals to provide energy-dense fat to survive the impending winter.
- In spring, there is not an abundance of plant-based foods, but the animals are getting leaner, so we get more protein and less fat and carbs.
- In summer, there is an abundance of plants that are easy pickings and the animals that we have to eat, like us, are getting pretty lean.
- Then, in autumn, we have a magical combination of foods with starch and fat available with less protein, enabling us to gain fat to survive the coming winter.
Autumn is a unique time when we can obtain foods that fill our glucose and fat fuel tanks simultaneously, raise our body weight set point and enable us to store more body fat. We know instinctively that this opportunity won’t last forever, so we make the most of it.
We get a double dopamine hit rewarding us for consuming as much as we can get of these magical foods that contain fat+carbs.
It’s hard to stop eating these fat+carb foods when they are available.
Luckily though, autumn doesn’t last for long (at least in nature), so we only gorge for a short period.
Fast forward to our present day, and for better and for worse, the industrialisation and commercialisation of our modern food system have created infinite autumn.
We’re like a squirrel that has worked out how to manufacture an infinite supply of acorns and is ready for a Game of Thrones-eseque winter. We no longer need to “endure” the limitations of the other seasons.
But unfortunately, as you can see from the chart below, along with the massive amount of extra fat and carbs in our food system, our obesity rates are also growing at an alarming rate.
This article attempts to unpack what is happening in nature to help us to better respond to the environment we now find ourselves in.
Whether or not you believe there is an interaction between our biology on a yearly basis (not just 24 hour circadian) and types of food that stimulates our appetite, I think this is a valuable way of navigating our modern food environment.
Don’t Eat for Winter
Many of the concepts in this article are gleaned from chats with Cian Foley and his book Don’t Eat for Winter. Cian has made some fascinating observations that helped me join some dots that I think are worth sharing.
Even if you don’t buy the whole Don’t Eat for Winter concept, learning to not ‘eat for winter’ will actually help you survive in your modern food environment.
If n=1s are anything to go by, the theory seems to be working pretty well for Cian (pictures below).
There is a ton of insights in Cian’s intriguing infographic below that I think are worth discussing in more detail. I know I didn’t see them all at first.
Body fat is what most people are interested in, so we’ll start by looking at how thinking seasonally affects body fat levels.
Our food and temperature environment is pretty stable these days thanks to fossil fuels, synthetic chemical fertilisers, modern agricultural practices and the invention of air conditioners and refrigerators. Humans have done a fantastic job of overcoming the threats of food scarcity and environmental pressures.
However, in days past our calorie intake and body fat levels would have fluctuated with the seasons so that we:
- build fat in autumn,
- work to maintain the fat through winter with energy-dense high-fat foods,
- lose fat in spring,
- maintain leanness through summer, and
- gain body fat in autumn ready for the process to start all over again.
The image below is from a study showing the seasonal variation in obese people in suburban Minnesota. You can imagine these sorts of fluctuations would be much more exaggerated in days gone by.
Crops like grains are harvested at the end of summer/start of autumn. Through winter we rely on fat when the carbs are gone. Cian’s chart below shows how the glycemic index of available foods changes with the seasons along with our typical change in body fat levels.
We build white adipose tissue (WAT) in autumn that turns into more metabolically active brown adipose tissue (BAT) in winter to combat the cold. We then lose the fat in spring and summer when we have the sun to keep us warm.
If we understanding how all this happens seasonally, we can then reverse engineer our food environment to give us a better chance of achieving our body composition and health goals.
Our food choices, energy intake, appetite and hormones are intimately interrelated. While calories count, hormones often dominate our appetite and drive us to eat more than we would like to. No matter how much willpower you have, appetite and hunger usually win out if your food environment is working against you.
Cian’s graphic shows three lines arcing through the middle representing a seasonal increase of insulin, ghrelin and dopamine which peak in autumn and are at their lowest in spring.
While you may like to think your conscious brain is in control, the reality is that much of what you do is instinctively driven by dopamine (particularly when it comes to things that are critical to our survival like food and sex).
We let our subconscious instincts and habits run the show most of the time so we can reserve our mental energy for really important decisions.
If your subconscious thinks that something is good for you, it will give a burst of dopamine to reinforce “good” behaviours, so we do it again.
In autumn, when both fat and carbs are available, we now understand that we get a “supra-additive” dopamine hit, much more than if we just ate fat or carbs alone.
So, like a drug addiction that is reinforced by the habit solidifying dopamine hit, we can also get addicted to modern foods. Despite “knowing better”, it’s hard to resist the food in your cupboard or the free cupcakes that your workmate brought for the third celebration this week!
Insulin rises as we get fatter to help us hold onto the energy that we eat. Insulin is an anti-catabolic hormone that acts as a brake on our liver to slow the release of stored body fat while we use up the food that is coming in from our diet.
In spring, we reverse the hormonal balance. Insulin decreases, and glucagon increases to force stored energy out when we only have more satiating protein and fibrous foods and less high-energy foods (fat and starch).
Lastly, we have ghrelin (a.k.a the hunger hormone) which seems to elevate when we have access to fuel from carbs and fat together (i.e. in autumn). This magical autumnal food combination signals that winter is coming. It’s time to get fat, so our body set point rises and we obediently go in search of more food.
Leptin is also lowered by fructose (which is plentiful in late summer) which means we think we are less fat than we actually are, so we put on more weight.
Insulin and leptin, and possibly ghrelin, function as key signals to the central nervous system in the long-term regulation of energy balance.
Consequently, decreased circulating insulin and leptin and increased ghrelin concentrations could lead to increased caloric intake and ultimately contribute to weight gain and obesity during chronic consumption of diets high in fructose. (Havel et al, 2004)
Our infinite autumn
Whether by design (by smart food scientists) or by trial and error (based on what sells the most), our modern food environment has become progressively more autumnal all year round.
Rather than cycling higher carb (summer) or higher fat (winter), the food industry has discovered that they can sell more foods when they mix carbs and fat together. It’s also very cheap to make foods that combine cheap subsidised flours with cheap seed oils to concoct just about anything you find on the shelf of your supermarket.
All you need is some artificial sweetener, artificial colour and artificial flavour optimised for the bliss point of your target demographic and you can make just about anything from some combination of seed oils and starch.
But it’s the use of flour and seed oils that have skyrocketed over the past 50 years in parallel with the obesity epidemic.
Over the last 100 years or so our intake of fat and carb in percentage terms have drifted together. We are now consuming the perfect low satiety autumnal formula all year long.
While there aren’t a lot of examples of foods that are a mixture of fat and carbs in nature other than breast milk that helps babies grow quickly into children…
…and acorns that help squirrels get fat for winter)…
…modern food processing now allows us to create more and more products that are a similar mix of fat and carbs. We can’t get enough of foods like the croissant,
… and chips that all follow the hyperpalatable low satiety autumnal formula!
The chart below shows the unique impact of the combination of starch+ fat on our appetite and satiety compared to other macro combinations. Hunger will ramp up steeply once you get past about 65% of your meal from fat+carbs (blue line). However, it seems, for whatever reason, that the combination of fat+starch has a much stronger effect on your hunger and appetite, driving you to eat much more than you would have otherwise.
What this means in practical terms is that your odds of sticking to your calorie restricted diet are slim if a significant amount of your diet involves some combination of fat+starch!
You may theoretically be able to lose weight on a diet of junk food if you can maintain a calorie deficit, but your chance of winning the war against hunger when you are eating only junk in the long term is minimal.
Conversely, by minimising the amount of energy that comes from starch+fat you will be able to mimic your body’s fat loss mechanism in spring (with decreased ghrelin and dopamine and increased glucagon) and shed your unwanted fat thereby escaping the infinite autumn!
How to escape the infinite autumn
Free pizza and the cookie jar at work that keeps getting refilled are hard to resist.
Over the years, many of us end up obese and diabetic.
If you’ve come to the realisation that you’ve been stuck in autumn and you want a way out, the natural option is to progress to winter foods which are higher in fat and lower in carbs.
Keto is the antidote to autumn
Keto or LCHF is effectively the antidote to autumn and allows you to draw down on the excess glucose stored in your body. Minimally processed low-carb foods are more satiating than the hyper-autumnal foods that are made possible by modern agriculture.
Reducing the carbs in your diet (moving to the left in the chart below) will improve satiety compared to the autumnal middle zone where we get carbs and fat together.
You will need to find your optimal carbohydrate ‘sweet spot’ guided by your appetite and blood sugars. While there are a growing number of people who swear by a carnivorous approach or a very high-fat ketogenic approach, pushing to eliminate all carbs (e.g. including non-starchy fibrous veggies) may not be necessary or optimal for everyone.
While many people find they lose weight on keto for a period, many also find that weight loss eventually stalls, particularly if they continue to rely on ‘fat to satiety’.
It’s at that point they need to move from winter to spring.
Don’t get stuck in winter!
In spring, both carbs and fat are hard to come by, so the amount of protein and fibre in our diet increases. This phase may look less appealing than the other seasons, but there’s nothing like it if you’re looking for effective fat loss.
Spring ends up looking a lot like a Protein Sparing Modified Fast. This is where the mix of fat and carbs don’t matter that much as long as you can push your protein up towards 40% of your energy intake. Prioritising protein will increase satiety so you won’t be a slave to your appetite.
During this period, ghrelin (hunger) and dopamine (mindless eating) reduce and insulin will start to fall as your calorie intake drops and you have less body fat to hold back in storage.
Similar to autumn and winter, you probably don’t want to stay in spring forever eating mainly lean protein foods. Once you have burned off all the body fat you want to you will want to get some more energy in your diet (hint: protein is not a great way to get your energy).
Once you’ve lost your weight and come back within your Personal Fat Threshold with stable blood sugars you can move on to summer.
If you’ve actually been able to draw down your blood sugar, summer foods will refill your glycogen stores which will fuel explosive activity.
Longer days signal the need to eat more in order to fuel more movement. In our modern environment with constant artificial lighting and looking into screens we are likely triggering this to some extent. Looking at a screen under artificial light throughout the year may unnecessarily drive your appetite.
As you can see from the chart below, sticking to high-carb foods with less fat (right-hand side) can be very satiating. Without added fats, these foods are virtually impossible to overeat. Your glycogen stores fill up, and your appetite switches off.
Because most of us are stuck in autumn, we’ll probably do better if we hang out in winter and spring for longer to draw down on our blood glucose levels and body fat levels before trying high-carb summer foods.
However, once your blood sugar and body fat levels are both low, you may want to test out your metabolic flexibility and enjoy the nutrient-dense foods that all the seasons (not the supermarket shelves) bring. Use your blood sugar as a guide to see if you’re ready for a new season.
As you can see in the chart above very high-carb plant-based foods can be more satiating than low-carb foods (as long as you resist the temptation to add lots of fat which will bring you back to autumn).
Some people like to toggle back and forth between winter and summer foods (both of which can be quite satiating) using a targeted ketogenic diet approach (i.e. consuming some fast-acting carbs around your workout) or a cyclic ketogenic approach (a day or two a week where you consume more carbs).
Cian Foley (pictured below before his second physique competition) mixes it up within the day, with one meal being high protein, another being high fat and another being high carb. This can add more variety and potentially more micronutrients.
The key is to avoid hyperpalatable carb+fat food combinations in the same meal will send you into a dopamine-fuelled feeding frenzy (e.g. dinner with dessert, blueberries with cream, fried rice, potato with butter, veggies with butter etc.).
You also need to allow enough time between meals for your blood sugar to drop back down to baseline. You don’t want to be coming into a high-fat meal with an elevated blood sugar from your high-carb meal, or you’ll just end up storing fat.
If you wanted to make seasonal eating a long-term way of life you could shop only at your local farmers market, grow your own produce and only eat fresh locally grown foods in season while avoiding unnatural food combinations.
If you spend plenty of time in winter, spring and summer then you will be able to enjoy autumnal celebrations when they come around. Because you are avoiding autumnal combinations in your day-to-day life, you may be able to recover quickly. However, some people may not be able to avoid spiralling out of control due to years of dopamine reinforced habits. For these people, long-term abstinence may be necessary.
The table below shows the characteristics of each of the seasons and how you can manipulate your diet.
|autumn||building fat||standard western||high||low||low||moderate||moderate||low|
|winter||blood sugar control||low carb/keto||moderate||moderate||moderate||low||high||moderate|
|summer||explosive activity||higher carb||moderate||moderate||moderate||high||low||moderate|
This chat with Paul and Cian is an excellent overview of the concept that I highly recommended checking out to solidify the ideas in this article.