Insulin resistance is a growing problem in modern society and has shown huge a increase over recent decades. Insulin resistance is clinically defined as the state in which a given concentration of insulin produces a less than expected biologic effect and, in turn, causes the body to not utilize insulin efficiently.
To compensate for this defect, the pancreas releases additional amounts of insulin to maintain normal blood glucose levels. In the nutrition circles it is commonly believed that carbohydrates are to blame for insulin resistance. This is in-so-much that when we eat carbohydrate our blood glucose levels rise and insulin is released to shuttle that glucose into the cells of the body to be used in ATP production or be stored as body fat.
As Jason Fung puts it insulin resistance occurs when the cells overflow glucose and the pancreas then produces more insulin to try and deal with the glucose overflow to no avail. This negative feedback loop continues until the person has both high levels of circuiting blood glucose and high levels of insulin until the cells become seemingly resistant to insulin’s effects and we become diabetic.
In Australia diabetes is a growing problem, the below chart shows how much of an issue this is and its growing.
I am not saying this theory is wrong but it appears there is more at play than just food when it comes to insulin resistance and diabetes.
Let’s shine some light on this.
Light’s role is insulin resistance
There is a growing body of evidence that suggests a link between blue and green light exposure after dark and lack of sleep.
This evidence also extends into blue and green light causing insulin resistance. I want to look at some studies to draw some conclusions on whether blue light is causing insulin resistance and whether eating under sunlight has the same effect as artificial light.
Morning and Evening Blue-Enriched Light Exposure Alters Metabolic Function in Normal Weight Adults
In this study in 2016 the researchers took 19 healthy adults and randomly assigned them to be exposed to bright blue enriched light either 0.5 hours or 10.5 hours after waking. Both groups were tasked with eating during this exposure as well.
The researchers then took subjective measures of sleep and hunger, as well as blood samples to measure glucose, cortisol, insulin, leptin and ghrelin, and compared these with the results when the participants were subjected to dim light. The findings showed that exposure to light, which was blue-enriched, in the morning and evening both led to higher insulin resistance.
Basically, if you eat your breakfast and dinner under artificial lights, scrolling through your smart phone or whilst watching television you are going to have a harder time digesting carbohydrate which will lead to weight gain and eventually diabetes.
Light Exposure During Sleep May Increase Insulin Resistance
This study from 2018 shows that just one night of blue light exposure causes can increase in insulin resistance.
Twenty healthy adults ages 18 to 40 were randomized into Dark-Dark or Dark-Light groups and run in parallel for a three day and two-night stay. Participants had eight hours of sleep opportunity each night starting at habitual bedtime determined from one week of actigraphy with sleep diary. The Dark-Light group slept in the dark < 3 lux on Night 1 and slept in overhead room light of 100 lux on Night 2, while the Dark-Dark group slept in the dark <3 lux on both Nights 1 and 2.
To put this into perspective street lamps give off at least 100 lux and if you do not have black out curtains this level of lux is shining into your room whilst you sleep. This is a common problem and also, if you or your partner gets up to use the bathroom in the night you will also be exposed to even higher levels of lux which will cause insulin resistance.
Results showed that a single night of light exposure during sleep acutely impacts measures of insulin resistance. Insulin resistance is the diminished ability of cells to respond to insulin action transporting glucose out of the bloodstream and precedes the development of type 2 diabetes.
Are active sun exposure habits related to lowering risk of type 2 diabetes mellitus in woman, a prospective cohort study?
A South Swedish cohort study comprising 1000 women from each age group between 25 and 64 (n=40,000) drawn from the Southern Swedish population registry 1990-1992. At the inception of the study 74% answered the inquiry (n=29,518) and provided detailed information on their sun exposure habits and other variables. A follow-up inquiry was sent 2000-2002 which 24,098 women answered.
The mean follow-up time was 11 years. Logistic regression analysis was used and the main outcome was the relationship between type 2 DM and sun exposure habits.
Our findings indicated that women with active sun exposure habits were at a 30% lower risk of having DM, as compared to those with non-active habits. There was an inverse relation between this risk reduction and BMI.
However, the study also showed that there was a seasonal difference in the risk factors with the summer months being lower risk of insulin resistance and the winter month’s being higher.
This fully enforces the idea behind seasonal eating. In the winter months carbohydrates will be less common as the weather will not allow them to grow. Eating them during winter months will have an increased chance of weight gain as your body will become more insulin resistant with less sun exposure. In the summer when the weather is good and the sun is shining carbohydrates grow meaning the body can process them better than in the winter months, as insulin resistance will be lower, if we eat our meals outside.
Being exposed to sunlight is therefore not the same as artificial light and both have different effects on insulin sensitivity.
Subcutaneous white adipocytes express a light sensitive signalling pathway mediated via a melanopsin/TRPC channel axis
It is very clear that dysfunctional white adipose tissue (WAT) is associated with the development of obesity, diabetes and cardiovascular disease.
This study has shown that the light photon receptor Melanopsin is found in the WAT. Activation of melanopsin reduces the size of lipid droplets and lowers leptin. It also reduces adiponectin. This means that exposure to the sun whilst eating helps reduce WAT which will reduce insulin resistance and risk of diabetes.
Your body wants food under light and from a circadian stand point this must be during sunlit hours, as its natural and in sync with circadian environmental clues, aka light/dark cycles. After dark we are not meant to be exposed to blue and green light as this disrupts our sleep, disrupted sleep = increased cravings. This is the fuel to the fire for insulin resistance!
Carbohydrates - The fuel to the Fire?
The current environment that we live in is characterized by constant exposure to blue and green light. Blue and green light is present in digital devices, televisions, computer monitors, LED and Fluorescent lighting, car highlights, LED display panels and street lamps. We are confined to blue lit offices during the day and exposed to blue light after dark. We do not get a lot of sun exposure and when we do we cover our skin with sunscreen and eyes with sunglasses which means we don’t get the benefits of lipid droplet reduction from melanopsin activation in the WAT. We are shielding ourselves from the very antidote to insulin resistance.
We eat most of our meals under artificial light, which has been shown to cause insulin resistance. When we continue to do this, we get more and more insulin resistant, fatter and diabetic. What fuels this fire is we eat carbohydrates under artificial blue light which is speeding up the development of onset and type-2 diabetes. Carbohydrates may not be directly causing insulin resistance, eating them under artificial blue light is.
When you look at the Mediterranean diet from a low carbohydrate diet perspective they argue that the diet consists of nuts, red meat, fish and vegetables. What they actually eat, aside from these things, is bread, pasta and grains and they don’t get insulin resistance. They don’t get insulin resistance from eating carbohydrates because they typically dine outside under sunlight, away from intense artificial light. These blue zone populations typically spend time outside and some even have diets high in carbohydrates such as the Okinawan’s. They have high life expectancy and low rates of insulin resistance. Why? Because they have warm temperatures, lots of sun and eat outside! When you look at large cities, anywhere in the world the same is not true, they eat under artificial light and get insulin resistant, sick and fat.
I am an advocate of a ketogenic or low carbohydrate approach to dieting as I believe it has additional health benefits but in the summer months I do not mind upping my carbohydrate intake and have seen no changes to body fat during the summer months, in fact I feel leaner.
Seasonally speaking I enjoy a ketogenic diet in the winter months, seasonal nutrient dense local produce is the way forward from a dieting standpoint.
These studies on light and insulin resistance are definitely food for thought on why some populations get sick eating carbs and other don’t. They literally shed light on why we have been getting more and more insulin resistant and it may not be solely down to carbohydrates, the root cause may be chronic artificial blue light exposure.
Your body wants to store fat more in the evenings, this is clear from the literature. We have seen in this article that being under sunlight reduced lipid particle size in WAT and we know that the body is less likely to store fat in the mornings.
Therefore, a good protocol to follow would be to have your largest meal in the mornings and smallest meal at night. Ideally you would fast after dark as there would be too much artificial blue and green light present but in modern society characterized by family dinners this is not always practical.
The adage goes, eat breakfast like a King, lunch like a Prince and dinner like a Pauper. Use this and you won’t go far wrong. When you must eat under artificial light, especially in the evenings make sure you are wearing red lens blue and green light blocking glasses, besides lowering the insulin resistance effect of eating under artificial light you will also properly sync your circadian rhythms and get a better night’s sleep and proper hormone production which is only a positive when it comes to health and wellness.
You will also want to cover as much of your skin as possible as melanopsin is also found in the skin and fat cells. You will also want to limit carbohydrate intake if you eat under artificial light or you will have a hard time processing it with progressive insulin resistance as the years go on.
Where you can eat your meals outside, under sunlight and in the summer if you want to increase your carbohydrate intake, and you medically can, go for it!
It's not just about what you eat, its about when you eat it and under what light.