Your Hunger is Controlled by LIGHT: Understand the circadian clock on hunger
Do this for weight loss and appetite control
Did you know that the amount of light you're exposed to can affect your hunger levels? There's a close connection between light and our appetite that has been extensively studied by researchers.
But how exactly does light control our hunger? And what can we do to make sure we're getting the right amount of light for optimal hunger control? In this article, we'll explore the connection between light and hunger and provide some tips on how you can harness the power of light to keep your appetite in check.
This information is useful for people trying to lose weight, as they can adjust their light exposure to help manage their appetite. It's important to make sure we have enough natural daylight during the day and limit artificial light at night, in order to maintain a healthy sleep-wake cycle and control our eating habits.
So, let's shed some light on this topic and dive into the science behind it all :-)
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How is hunger controlled by light?
It's quite fascinating how our bodies are influenced by light. At the core of this connection between light and hunger lies our internal circadian clock, which is responsible for regulating various physiological processes in our bodies, including hunger levels.
Your energy levels and how your body functions can be affected by the amount of sunlight you are exposed to. This is because light affects the production of hormones, such as melatonin, which helps regulate sleep and appetite.
Studies have shown that the length of daylight can also impact weight gain in animals and humans. However, it is difficult to determine the exact role of daylight on energy levels because other factors like temperature, physical activity, and diet can also vary with the seasons. Artificial lighting at night can make it seem like it is always summer or daytime for our bodies, which can disrupt natural rhythms, which affect our metabolism.
Changes in daylight can also impact our internal biological clocks, which regulate things like sleep patterns and hormone production. These changes may affect energy metabolism and homeostasis, the process of maintaining a stable internal environment.
Scientists believe that this connection between daylight and our internal clocks may act as a "seasonal clock" that affects how our bodies deal with energy. So it’s important to be mindful of how much light we are exposed to, especially at night, as it can impact our overall health and well-being.
This brings me to a study by Frank A. and colleagues that looked at the relationship between light and hunger. The study involved 12 healthy individuals who were kept in a lab for 13 days with controlled sleep and meal times, evenly spread throughout their internal circadian cycle.
The researchers found that there was a significant endogenous circadian rhythm in hunger, which goes up in the evening and dropping in the morning. This can explain why people are not typically hungry in the morning, despite having fasted overnight. The study also found that our appetite for different types of food, such as sweets and meats, follows a similar circadian pattern. So our cravings are in fact on a schedule!
But wait, what exactly is an endogenous circadian rhythm?
Simply put, it's a natural internal cycle of physiological processes that repeats itself every 24 hours, influenced by external factors such as light and dark.
How Can Light Affect Our Hunger?
Now that we know about the connection between light and our internal circadian clock, let's delve into how exactly light influences our hunger levels.
I will review a fascinating study by Lewin S. and colleagues that examined the effects of light on gene expression in different tissues including the liver, muscle, white adipose tissue, brown adipose tissue and hypothalamus.
The study aimed to investigate the effects of different photoperiods (light periods) on body weight, fat mass, energy expenditure, and metabolism in mice. They used two different strains of mice, one that produces melatonin (C3H/He) and one that does not (C57BL/6N).
Body Weight and Fat Mass
The mice fed with a high-fat diet were randomized into two groups for 8 weeks, one group exposed to a short light photoperiod of 6 hours light and 18 hours dark, and the other group exposed to a long light photoperiod of 18 hours light and 6 hours dark. The results showed that both C3H and C57BL/6N mice displayed a similar decrease in body weight and fat mass when exposed to the short light photoperiod. This suggests that the effect of photoperiod on body weight and fat mass was not affected or controlled by melatonin as all the mice lost weight with short light periods.
Energy Intake and Expenditure
There was no significant difference in energy intake between the two groups, indicating that both C3H (the mice that produced melatonin) and C57BL/6N mice consumed similar amounts of food regardless of the light period. However, there was a slight difference in energy expenditure between the two groups, with C3H mice showing a slightly higher energy expenditure during the light period compared to C57BL/6N mice. This could suggest that C3H mice may have a higher metabolic rate during the light hours. This suggests that our melatonin production is important for weight loss.
Rhythmicity of Liver Metabolism
The study also examined the effect of photoperiod on liver metabolism and found that there was no significant difference in plasma non-esterified fatty acid levels, blood glucose levels, or liver glycogen levels between the two groups. However, there was a significant difference in liver triglyceride content between the two groups during the light period, with C3H mice (melatonin producing mice) having higher levels compared to C57BL/6N mice. This suggests that photoperiod may have an effect on liver fat content, particularly in C3H mice.
They also found that exposure to less light can affect weight gain in mice.
In a nutshell, we can say that light has a significant influence on gene expression, and understanding the mechanisms behind this can help us better understand how our body responds to different lighting conditions.
What does evening blue light do to hunger?
It's so interesting to find out that not only does light affect our sleep patterns and metabolism, but it also has an impact on our hunger levels. I will just explore one more study by Ivy N. Cheung and colleagues which shows that exposure to morning and evening blue light increases hunger.
This research was conducted on 19 healthy adults aged from 20 to 39 years old. The study consists of two groups: a morning group (9 people) and an evening group (10 people). Both groups had similar characteristics in terms of age, BMI, sleep schedule, and exposure time to light above certain levels.
The participants were exposed to either dim or blue-enriched light for two days, and their responses were recorded. The researchers wanted to determine any significant differences between the dim and blue-enriched light conditions.
The results showed that there were significant differences in hunger levels between the dim and blue-enriched light conditions, with participants feeling hungrier when exposed to blue-enriched light.
This was seen in both morning and evening groups, indicating that exposure to either type of light can increase hunger levels regardless of the time of day. Additionally, there were no significant differences between the morning and evening groups in terms of demographics and other characteristics.
Final Word on Light and its Effects on Metabolism and Energy Balance
Light plays a crucial role in regulating our body's metabolism and energy balance. Studies have shown that exposure to different types of light can affect our sleep patterns, appetite and cravings, and eventually our food intake.
This knowledge can help us make informed decisions about our lighting environment and potentially improve our overall health and well-being.
Being very mindful about limiting blue light exposure helps us regulate our circadian rhythm and balance in our cells. This apparently has a huge impact on our metabolism, sleep and therefore overall health.
Keypoints and Takeaways
Exposure to different light periods has a small effects on body weight, fat mass, energy intake, and metabolism in mice.
Light exposure can affect gene expression and ultimately impact our overall health and well-being.
In humans, the type and timing of light exposure can influence hunger levels, with blue-enriched light increasing hunger in both morning and evening groups.
Our appetite for different types of food, such as sweets and meats, follows a similar circadian pattern - being higher in the evening and lower in the morning.
Hunger levels change with notable differences when one is exposed to dim and blue-enriched light conditions. Participants feel hungrier when exposed to blue-enriched light.
So as our hunger and cravings increase in the evening, try to limit the blue light exposure as that will increase the craving further.
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I hope you enjoyed the article today! I wish you all a great week!
Susanna