Light, Circadian Rhythm, and Weight Loss in Norwegian Winter

By Dominic Lamb – LightTherapy.no

February or March. Not January - January people are still motivated. February and March is when the real ones show up. They'd done everything right: tracked their calories, trained three or four times a week, slept their eight hours. And they were heavier than they'd been in October. Sometimes by three kilos. Sometimes by five. They weren't making excuses. They were genuinely baffled. And honestly, back when I was a personal trainer, so was I.

Norwegian winter weight gain is not primarily a willpower problem, a dietary failure, or a consequence of moving less - though all of those can contribute. The deeper driver, and the one almost nobody in the weight loss industry discusses, is the catastrophic mismatch between the light signals Norwegian bodies receive from November to March and what human cells actually require to regulate metabolism properly. Light timing controls whether your fat cells burn stored energy or accumulate more of it, and for roughly half the year in Norway, the signals point overwhelmingly toward storage.

Your fat cells have their own clocks - and you're confusing them

This is the thing that would have completely reoriented my approach as a personal trainer if I'd known it then. Fat cells - adipocytes - contain their own molecular oscillators. Internal clocks that determine whether the cell is in burning mode or storing mode at any given time. They don't just respond to what you eat. They respond to when, and they use light-dark timing as one of their primary synchronisation signals.

A 2014 study published in PLOS ONE found that the timing and intensity of light exposure correlated with body mass index independently of how much people ate, how much they exercised, or how long they slept. The effect was specifically about light timing. You can read the paper here: https://pubmed.ncbi.nlm.nih.gov/24718911/

Research following bariatric surgery patients over six years found that those who ate their main meal earlier maintained significantly greater weight loss - regardless of total calories, food composition or sleep. The meal timing effect was driven by circadian alignment. When you eat in the window your biology expects food, your fat cells respond differently than when you eat outside it.

The signal that synchronises these clocks? Light. Specifically: the timing, intensity and spectrum of light hitting your eyes and skin across the full day. Get those signals right and your metabolism runs with the biology. Get them wrong - which Norwegian winter almost guarantees - and the biology defaults to storage.

What is actually happening in your cells

Your mitochondria are where this gets interesting, and where red light therapy (rødlysterapi) connects directly to weight management rather than being just a recovery or skin tool.

Cytochrome c oxidase - the terminal enzyme in your mitochondrial electron transport chain - has absorption peaks in the red (around 630-660nm) and near-infrared (around 810-850nm) ranges. When photons at those wavelengths reach that enzyme, they drive electron transport and increase ATP production. The mitochondria ramp up output. And when output increases, glucose demand increases - your cells pull more glucose from the bloodstream to fuel that production rather than routing it toward fat storage.

Professor Glen Jeffery's group at UCL demonstrated this directly. In a study published in the Journal of Biophotonics in 2024, just 15 minutes of 670nm red light before a glucose tolerance test reduced blood glucose elevation by 27.7% over two hours. Maximum glucose spiking was reduced by 7.5%. The light was changing how efficiently the body processed glucose by increasing mitochondrial activity. Read the paper: https://pubmed.ncbi.nlm.nih.gov/38010845/

That matters for weight loss because glucose that gets burned for ATP is glucose that doesn't get converted to fat. This is why I use a red light panel before training in winter - not primarily for the recovery benefits, though those are real, but because I want my mitochondria running properly before I ask my body to do anything metabolically demanding. Morning red light therapy in winter is, among other things, a way to provide the wavelengths that Norwegian sunlight isn't delivering during those months.

There's also a melatonin dimension here that most people don't know about. Work by Dr. Russel Reiter and optical engineer Scott Zimmerman has shown that mitochondria produce melatonin locally - independently of the pineal gland - in quantities that dwarf systemic melatonin levels. This mitochondrial melatonin is produced in response to oxidative stress and near-infrared light exposure. It protects mitochondrial membranes, neutralises free radicals, and maintains the redox state that allows efficient energy production. When you exercise outdoors in sunlight, the near-infrared component of that light is stimulating this protective system. Studies show plasma melatonin can spike to around 200 pg/mL during intense outdoor exercise in sunlight - that's not coming from your pineal gland, it's the mitochondrial response. In Norwegian winter, training indoors under LED lighting, you're getting almost none of that. The morning red light panel session is a partial substitute - and I'd take partial over nothing. Reference: https://pubmed.ncbi.nlm.nih.gov/36671072/

The circadian synchronisation system - and where Norway breaks it

Light also works through your eyes to coordinate your entire metabolic system. Melanopsin-containing retinal ganglion cells send signals from your retina to the suprachiasmatic nucleus (SCN), which is your master circadian clock. The SCN then coordinates peripheral clocks in your liver, pancreas, muscles and fat tissue - effectively running a metabolic timetable across your whole body.

When you get bright light (above roughly 500 lux) in the morning, you're setting that timetable: daytime, burn energy, process food efficiently, be active. When you miss that morning signal - which happens routinely in Norway between November and February, when most people drive to work in the dark and sit under 200-300 lux office lighting all day - the timetable never gets properly set. Your peripheral clocks drift. Your fat cells receive ambiguous signals about whether to burn or store, and in the absence of a clear daytime signal, they default toward the more conservative option.

Recent research has found high levels of melanopsin in fat cells themselves. Your adipose tissue is directly light-responsive - not just downstream of the pineal gland, but reading light signals in its own right. Think about what that means if you're sitting in a warm living room in winter, wearing blue-light-blocking glasses, in shorts and a t-shirt: the glasses protect your eyes, but your skin is still receiving the ambient light signal. It's one of the reasons I write about why blue light blocking has to go beyond just glasses - the system is more distributed than most people realise.

The evening side of this compounds the morning problem. LED lighting in Norwegian homes typically runs at 4000-6000 Kelvin - blue-dominant, red-starved, the opposite of the warm evening spectrum your circadian system expects. As Professor Jeffery has pointed out repeatedly, modern LED lighting provides essentially none of the red and near-infrared that incandescent and natural light delivered. Your mitochondria are starved of the wavelengths they need. Your SCN receives signals that read as midday even at 9 PM. Cortisol stays elevated when it should be falling. Melatonin is suppressed. And the hormones that govern hunger - leptin and ghrelin - shift in exactly the wrong direction: less satiety signalling, more hunger, more cravings in the evening. That drive to eat at night isn't weakness. It has a biological mechanism, and light is running it.

A study published in PLOS ONE found that blue-enriched light in the evening produced higher insulin resistance and higher peak blood glucose than dim light - despite participants eating identically. The same blue-enriched light in the morning improved alertness with no metabolic downside. Timing is everything here. The paper: https://pubmed.ncbi.nlm.nih.gov/27070252/

The woman who lost four kilos without changing her diet

After I left personal training and moved into light therapy, I worked with a woman in her mid-forties who'd been stuck at the same weight for two years. She trained hard, ate carefully, slept reasonably well. Nothing moved. We didn't change her calories. We didn't change her exercise programme. We changed her light environment and her meal timing.

20-minute outdoor walk every morning, regardless of weather or darkness - this is non-negotiable, whatever light exists outside is better than none, and the cold itself has additional metabolic benefits I won't fully get into here. 10-15 minutes of red light panel on her torso after the walk. Largest meal of the day within two hours of that morning light exposure. No eating after 7 PM - her kids were young so family dinners were early anyway. Overhead lights off after 6 PM, warm lamps only, blue-blocking glasses from 8 PM. Grounding sheet for sleep.

Eight weeks. Four kilos. Same calories, same training, same sleep duration. But the things she mentioned that mattered more than the number on the scale: evening hunger that had driven her to snack every night essentially stopped. Morning energy that had been consistently poor became reliable. She'd been cold all winter - one of those people who's always reaching for an extra layer - and that improved too, which I wasn't surprised by given what we know about fat cell thermogenesis and circadian synchronisation. A properly entrained metabolic system burns more energy as heat. When it's not entrained, you feel cold and you store more. These aren't separate problems.

The protocol - what actually changes things

Morning light exposure is the foundation and it's non-negotiable. Get outside within 30-60 minutes of waking. Even in December, even if it's dark, the ambient light outdoors on a cloudy Norwegian morning is still providing signals your indoor lighting cannot match. Ten to twenty minutes is enough to begin moving the needle on circadian phase. If you're north of the Arctic Circle and dealing with genuine polar night, a full-spectrum lamp is a reasonable substitute, though not ideal - I'd rather you used a reptile lamp than a standard SAD box, for reasons to do with spectral quality that I've covered elsewhere.

Add red and near-infrared light to your morning. 10-15 minutes on your torso with a properly specified panel - wavelengths around 660nm and 830-850nm, at therapeutic irradiance measured at real treatment distance, not marketing distance. (I test mine with a spectrometer. I've sent panels back when the measured output didn't match the spec. That's how you know what you're actually getting.) In an ideal sequence: outside first for the circadian signal through your eyes, then red light for the direct mitochondrial effect on tissue. When that's not possible, both in the morning is still far ahead of neither.

Shift your eating window earlier. Your largest meal within a few hours of your morning light exposure - insulin sensitivity peaks in the morning and diet-induced thermogenesis (the calories you burn just digesting food) is measurably higher then than in the evening. The same meal eaten at 8 AM burns more calories in processing than the same meal eaten at 8 PM. That's not a metaphor. A study in women with metabolic syndrome published in Obesity journal found that high-calorie breakfast versus high-calorie dinner produced greater weight loss and improved metabolic markers despite identical total daily intake. Reference: https://pubmed.ncbi.nlm.nih.gov/23512957/. Try to avoid eating within two to three hours of bedtime. When melatonin is rising, glucose tolerance is at its lowest. Food eaten late gets processed poorly and stored efficiently - the exact opposite of what you want.

Protect your evening environment. Overhead LEDs off after 6 PM. Warm lamps, 2700K or lower, positioned at or below eye level. Blue-blocking glasses from around 7 PM. If you have to work on screens in the evening, warm lamp and glasses on - the work still gets done, the sleep doesn't suffer. I do it regularly and can confirm it's entirely workable once you've adjusted to the visual warmth. Candles after 8 PM if you want to go further - firelight is so red-shifted it has almost no impact on melatonin, which is exactly the point.

Be consistent rather than perfect. These are entrainment signals, not single-dose interventions. Your circadian system responds to repeated, reliable patterns over days and weeks. One morning of outdoor light won't undo months of misalignment, but two to three weeks of consistent practice will shift things meaningfully. The woman above saw the scale move in eight weeks. Most people notice something within the first two.

Consider grounding as a complement. I keep returning to earthing products because the electron transfer from direct ground contact affects cellular voltage and mitochondrial function in ways that interact usefully with light therapy. Dr. Gerald Pollack's work on structured water (EZ water) is relevant here - near-infrared light and grounding both affect the fourth phase of water inside cells, which influences how efficiently nutrients enter and waste exits. It's a rabbit hole, but a real one. I take a grounding mat on holiday - I am one of those people now, and I have no shame about it.

For a deeper look at how morning red light specifically affects blood sugar - which connects directly to what's happening metabolically with weight - the post on morning red light therapy and blood sugar goes further into the Jeffery research and what it means practically.

The thing the weight loss industry won't tell you

Weight loss advice in 2026 is still overwhelmingly focused on calories in versus calories out. Which isn't wrong - energy balance matters. But it's an incomplete model, and in Norwegian winter specifically, it leaves out the variable that is most actively working against you.

Your adipocytes are not defective. They are responding rationally to the signals they're receiving. A circadian system that isn't receiving clear daytime light produces a fat cell that doesn't know when to burn. An evening environment flooded with blue-dominant light produces a hormonal state that drives hunger, reduces satiety, elevates cortisol and impairs overnight metabolic recovery. You can try to override that with more discipline and harder calorie restriction. Some people manage it. But it's fighting uphill, and the hill gets steeper through the winter months as the deficit in natural light exposure accumulates.

Change the signals, and the response changes. "Nothing changes if nothing changes" - I keep coming back to that because it's both obvious and underappreciated. A 20-minute walk in the dark at 7 AM, a red light session before breakfast, warm lamps in the evening: none of these feel like dramatic interventions. But they're speaking directly to the system that determines what your cells do with the food you eat. That's where the leverage is.

Questions about protocols specific to your situation - message me. I'm at the FAQ page for general guidance, or you can contact me directly. The devices I stock meet research specifications, stock is held in Norway for fast delivery, and you can pay via Vipps, Klarna or Stripe. But more than the equipment, I want you to understand the biology - because when you do, you stop guessing and start making decisions that actually move the needle.