Your skin turns green. Not dramatically, not overnight, but gradually, the way a tan builds over summer. Chloroplasts embedded in your skin cells begin absorbing sunlight and converting carbon dioxide and water into glucose. You are now, technically, a plant. Sort of.
The first morning you step outside and feel the sun on your arms, something is different. It's not warmth. It's closer to satiation. That low-level background hunger you carry between meals fades slightly, like you've just eaten a biscuit without eating a biscuit.
Don't get too excited. The maths on this are unkind.
The energy problem
A human body at rest burns roughly 80 watts of power. That's your basal metabolic rate, the energy needed to keep your organs running, your heart beating, your brain thinking about lunch. Walking bumps it to around 200 watts. Running pushes 800 or more.
The sun delivers about 1,000 watts per square metre at Earth's surface on a clear day. The average adult has approximately 1.7 square metres of skin. So you're catching 1,700 watts of raw sunlight, which sounds promising until you learn that photosynthesis is only about 3-6% efficient. Real-world plants convert a fraction of the light they receive into usable chemical energy.
At 5% efficiency, your skin produces roughly 85 watts in direct noon sunlight. That barely covers your resting metabolism. The moment you stand up, walk to the kitchen, or do anything more strenuous than lying perfectly still in a field, you need food.
Photosynthesis doesn't replace eating. It supplements it. You'd still need breakfast. Just maybe a smaller one.
The sunbathing economy
Despite the modest caloric contribution, the cultural shift would be enormous. Sunlight is now food. Not metaphorically. Literally.
Office workers near windows become the envy of their colleagues. Corner offices with floor-to-ceiling glass gain an entirely new dimension of status. Companies install UV-transparent panels in ceilings and walls. "Solar break" replaces "lunch break" in workplace legislation. The Health and Safety Executive issues guidance on minimum daily light exposure for employees, treating inadequate sunlight as equivalent to inadequate nutrition.
Outdoor professions gain prestige. Farmers, construction workers, lifeguards, anyone who works in direct sun is now getting paid and fed simultaneously. Office workers, by contrast, are spending money on food they wouldn't need if their employer provided adequate natural light. The class dynamics of indoor versus outdoor work invert.
And sunscreen becomes genuinely controversial. It blocks UV. UV drives photosynthesis. Wearing sunscreen is now the equivalent of skipping a meal. The dermatology community finds itself in an impossible position, arguing that skin cancer risk outweighs the caloric benefit while the public ignores them in favour of topping up their glucose levels at the beach.
Geography reshapes power
Countries near the equator receive more solar energy per square metre per year than those at higher latitudes. Ecuador gets roughly 2,000 kilowatt-hours per square metre annually. The UK gets about 900. Norway, in winter, gets almost nothing.
If sunlight is food, equatorial nations are the breadbaskets of the world. Their populations need less imported food. Their healthcare costs drop. Their economic output per capita rises because workers spend less money on calories. The geopolitical implications are substantial.
Northern countries experience something that looks a lot like seasonal famine. Not actual starvation, because conventional food still exists, but a measurable increase in food dependency during winter months. Seasonal Affective Disorder acquires a physical component. You're not just psychologically low in January. You're hungry, genuinely, because your skin hasn't produced meaningful glucose in weeks.
Migration patterns shift. Retirement to the south of Spain isn't just for the lifestyle any more. It's a nutritional strategy.
Fashion changes permanently
Clothing is now a barrier to food production. Every covered square centimetre is a square centimetre not photosynthesising. The pressure to expose skin is constant and, for the first time in history, backed by a biological argument rather than a cultural one.
Summer fashion becomes minimal everywhere, not for aesthetics but for efficiency. Business dress codes collapse. You can't ask employees to wear long sleeves and then wonder why they're hungry and sluggish by 3 PM. Ties are the first casualty. Full suits follow within a year.
Winter clothing creates a genuine dilemma. Cover up and stay warm but hungry, or expose skin and photosynthesize but freeze. Textiles companies race to develop UV-transparent fabrics that let light through while retaining heat. The first working prototype, which looks like wearing cling film, sells out in hours despite costing £200 per shirt.
The night shift problem
Night shift workers already have it rough. Disrupted circadian rhythms, higher rates of cardiovascular disease, that general sense of living slightly out of phase with reality. Now add to that a complete inability to photosynthesise during working hours.
A night shift worker gets zero solar calories during their shift. They sleep during daylight hours with curtains drawn. They are, for practical purposes, living like a non-photosynthetic human in a world that has restructured itself around photosynthesis. Their food costs are higher. Their energy levels are lower. The gap between day workers and night workers becomes a measurable health inequality.
Hospitals, which run 24 hours and have always relied on night staff, face a new staffing crisis. Night shift nurses are consuming 20-30% more food than their daytime colleagues for the same work. The NHS, already stretched to breaking point, now has to budget for supplementary meals it never needed before.
Green is the new normal
The colour thing takes getting used to. Within a generation, green skin tone becomes baseline. Beauty standards adjust, because beauty standards always adjust. Skin tone variation still exists, ranging from pale sage to deep emerald depending on genetics and sun exposure. The tanning industry pivots from bronze to deeper green. "You look so green" becomes a compliment meaning "you look well-fed and healthy."
There are holdouts. People who refuse the chlorophyll modification on religious or philosophical grounds, or who simply prefer their original skin tone. They eat normally, look the way humans have always looked, and become a visible minority in a world of green-skinned people. The social dynamics of this are uncomfortable to contemplate and entirely predictable.
Children born with chlorophyll skin don't know anything different. They grow up thinking it's perfectly normal to stand in the garden for twenty minutes before school, charging up. They're confused by old photographs of pink and brown people. "Why didn't they just go outside?" they ask, and nobody has a satisfying answer, because the honest one is: we couldn't. We were a different kind of animal then. We ate the plants instead of being them.