The Brightest Thing In The Body
An essay on sugar, cortisol, and what your body was built to burn before the world taught it to stay full
There is a kind of photograph doctors take of the inside of a living person. It is called a PET scan. Before the scan, they inject a small amount of glucose that has been tagged so a camera can follow it. Then they wait. The sugar travels everywhere the blood goes, and the camera watches to see which tissues grab it fastest and hold it longest.
When there is cancer in the body, the cancer is usually the brightest thing on the picture.
Not because it is large. Often it is small. It glows because a cancer cell is the hungriest thing in the body for sugar. It reaches out, pulls glucose in faster than the tissue around it, locks a phosphate onto the molecule so it cannot escape, and then burns it in a wasteful, frantic, primitive way that a healthy cell would be ashamed of. A man named Otto Warburg noticed this almost a hundred years ago, in the 1920s. Cancer cells ferment sugar even when there is plenty of oxygen to burn it cleanly. They choose the crude fire. We still do not fully agree on why. What we agree on is the appetite. The tumour eats sugar like it is starving, and on the scan that appetite becomes light.
I want you to keep that image in your mind. A body, lit up in the dark, and the brightest part of it is the part that is sick.
Because the story underneath that image is the same story underneath a great deal of what young women and young men in our cities are quietly struggling with right now.
The exhaustion that doesn’t go away after a night’s sleep.
The weight that arrives around the middle and refuses to leave when you want it to.
The cycle that has gone strange.
The mood that drops at nine in the evening like a glass bottle.
The zomato order that you do after it.
Different doctors, different waiting rooms, different names on the prescription. One thread runs through all of them, and the thread is sugar, and what your body does with it.
Start with what the body was actually designed for, because the design is older than the problem.
For almost all of human history, food was uncertain. The body that survived was the body that could run on whatever it had. When you eat, you burn sugar. When the sugar runs out, a well-built body shrugs and switches over to fat, and burns that instead. Between meals, through the night, across a lean week, it pulls from its own stores and keeps the lights on. Physiologists have a phrase for this ability to change fuels as the situation changes. They call it metabolic flexibility. A 2017 review in the journal Cell Metabolism described it plainly: a healthy body moves easily from burning fat in the fasted state to burning glucose after a meal, and back again, without drama.
This is one of the quiet miracles of being alive. You are a furnace that knows how to change what it eats.
The fasted body, the body that has not seen food for some hours, runs mostly on fat and on lactate and, if the fast goes longer, on ketone bodies made from fat in the liver. That is its calm, default state. The morning body, before breakfast, is meant to be sipping from its own reserves. This is not deprivation. It is the resting metabolism of a healthy animal, and the tradition I come from understood it long before there was a journal to print it.
Now look at the life most of us actually live.
We wake and reach for sugar within the hour. We eat again three hours later. We keep a sweet drink at the elbow through the afternoon. We are never, across the whole arc of a day, allowed to run out. The blood stays full of glucose from waking to sleeping. And a body that is never asked to switch fuels slowly forgets how. The furnace that once burned anything becomes a furnace that can only burn sugar, and panics the moment the sugar dips. That panic has a name too. We call it a craving. We call it the three o’clock crash. We call it hangry. It is the sound of a flexible system going stiff.
Sugar is only half of it. The other half is a hormone you have heard of for the wrong reasons.
Cortisol gets talked about as the stress hormone, as though its only job were to make you anxious. Its real job is older and more practical. Cortisol manages your fuel. When the body senses a demand, a threat, a cold morning, a hard effort, the first thing cortisol does is push sugar into the blood so the muscles and the brain have something to burn. It tells the liver to manufacture fresh glucose. It tells the rest of the body to ignore insulin for a while so that the new sugar stays in the blood where the emergency can reach it. Within minutes of cortisol rising, blood sugar rises with it. This is beautiful machinery when the threat is real and brief. A lion. A sprint. A genuine cold.
The machinery breaks when the threat never ends.
The modern threat is a meeting that went badly, a message that has not been answered, a relationship that costs more than it gives, a phone that buzzes at midnight, a city that never lowers its voice. None of these require you to run or to fight. But the body cannot tell the difference. It hears threat and it does the only thing it knows. It raises cortisol, and cortisol raises sugar, and the sugar has nowhere to go because you are sitting at a desk, and so it sits in the blood. Day after day, year after year, the blood runs sweet for reasons that have nothing to do with food.
The hormone doctor Sara Gottfried keeps a short list of the things that drive a young woman’s blood sugar out of rhythm, and food is only one item on it. The others are sleep, alcohol, perceived stress, the relationships that drain her, and a body that has stopped moving. Five of the six have nothing to do with what is on the plate. They are about the life, and the nervous system living it.
Here is where the thread pulls tight, so follow it slowly.
When blood sugar stays high, the body does the sensible thing. It releases insulin, the hormone whose job is to clear sugar out of the blood and put it away into storage. If the sugar is high all the time, the insulin is high all the time. And insulin carries a second message under the first one. Insulin is a growth signal. When insulin is in the blood, it is telling every cell that food is plentiful and the time is right to build, to divide, to grow. That message is healthy in a child who is supposed to grow. It is a different thing entirely in an adult body where the cells are supposed to hold steady.
Chronically high insulin is one of the loudest growth signals a modern body ever hears. And growth is precisely the thing that has gone wrong in the cell that glows on the scan.
This is not a claim that sugar causes cancer in any simple, frightening way. The body is far more complicated than that, and anyone who tells you one food will save you or doom you is selling something. What the research shows is quieter and more serious. Chronically elevated insulin and its cousin, a molecule called IGF-1, act on cells through the same growth pathways that tumours exploit. A large body of work, including studies on breast cancer survivors published in the Journal of Cancer Research and Clinical Oncology, has found that high fasting insulin and high IGF-1 travel with greater risk and greater recurrence. The same growth signal that helps a healthy child reach her height can, in the wrong body at the wrong time, give an already-confused cell exactly the encouragement it was looking for.
The hungry cell on the scan and the high insulin in your blood are speaking the same language. That is the thread.
Now watch the same lever move a different organ.
Polycystic ovary syndrome is one of the most common hormonal conditions affecting young women, and for a long time it was treated as a mystery of the ovaries. We understand it better now, and the centre of the picture is insulin. When insulin runs high, it travels to the ovary and switches on the machinery that makes male hormones, the androgens. It does this directly, by waking an enzyme called P450c17 inside the ovarian cells, and indirectly, by lowering a protein in the blood that normally keeps testosterone bound and quiet. So the testosterone rises, and it rises free. The ovary becomes androgenised. The cycle goes irregular. The skin and the hair change. And around it all sits a self-feeding loop, because the high androgens worsen the insulin, and the high insulin worsens the androgens, and the wheel turns.
A young woman is told she has a cyst problem, or a period problem, or a skin problem, or a weight problem. Underneath all four, often, is a sugar problem wearing four different costumes. For the wider treatment of this condition and the renaming the lineage anticipated by decades, see Upstream of the Lab Report.
The notes I once took from Dr Gottfried’s teaching framed the same truth from the other direction. She talked about the ratio of testosterone to estrogen, about how androgens behave across a woman’s twenties, about a continuous glucose monitor as a window into a whole life. The window matters because the glucose line on that monitor records far more than meals. It records stress, sleep lost, a body sitting still, a drink taken to take the edge off a day. The line is the life, drawn in sugar.
And the lever does not stop when the years move on. It waits at the far end of the decade too.
When a woman approaches menopause and her estrogen begins to fall, something happens in the brain that almost nobody warns her about. Estrogen, it turns out, is one of the master conductors of how the female brain uses glucose. It helps the brain pull sugar in and burn it for energy. When estrogen withdraws, the brain’s ability to feed itself with glucose dips with it. The work of Lisa Mosconi and her colleagues at Weill Cornell, using brain scans across the menopause transition, found that the brain’s glucose metabolism slows by something like twenty to thirty percent in this window. The fog, the word that will not come, the strange new fatigue, are real and physical. They are a fuel problem in the most important organ she owns.
The same molecule, glucose, that the tumour grabbed too greedily, that cortisol pushed too high, that insulin used as a growth signal, is now the molecule the ageing brain cannot get enough of. Too much in the blood for forty years. Then, in the brain, suddenly too little. The metabolism that was never taught to be flexible has the hardest time of all when the ground finally shifts. For the longer treatment of this transition and the framework the lineage has carried for it, see Charaka knew.
I am not telling you this to frighten a woman in her thirties about a decade she has not reached. I am telling you because the brain that arrives at menopause is built from the choices of the twenty years before it. The flexibility you keep, the rhythm you build, the way you let your body run lean between meals and burn its own fat without panic, all of it is being decided now, in the decade you are standing in.
So why write this for the ones who are twenty-eight, thirty-one, thirty-three. Why not wait until it hurts.
Because the body you are carrying right now is at the exact age where the architecture is still wet. The first small cracks are showing. The sleep that is not quite enough. The waist that has started to thicken. The cycle that skipped. The afternoon that collapses. Read them correctly and they are early letters from a metabolism asking to be allowed, occasionally, to run on something other than sugar, and they have very little to do with willpower. And at this age the letters are still gentle, and the body still remembers how to answer them. Ten years from now the same letters arrive in harder ink.
This is the most leveraged decade you will ever have over your own furnace. The bills have not yet come due. The principal can still be paid down.
Here the tradition I serve has something old to offer, and it offers it without a single promise of dramatic results.
The rishis did not have the word glucose. What they had was a body, watched closely across generations, and a set of disciplines built around its rhythms. They built fasting into the year and the week and the day, and they called it upavasa, which means to dwell near, to sit close to the higher part of yourself while the lower appetites rest. They understood, without a laboratory, that a body occasionally emptied is a body kept supple. They built the day around two hinges, the dawn and the dusk, the sandhya, the transition hours when the system is most willing to be re-set. They taught that you should eat a little, move a little, rest a little, and that the path has no finish line, only a slow deepening of discipline. Drop by drop on parched earth.
What does this give a body that is forgetting how to switch fuels.
It gives it the practice of going without, gently and often, so that the furnace remembers its second fuel. It gives it a morning that begins with breath and stillness instead of sugar, so that the cortisol that rises on its own at dawn meets a calm nervous system instead of a panicked one. The slow exhalation of mantra and pranayama tones the vagus nerve and lowers the body out of its defensive state, and a body that is not braced for threat is a body that does not pour cortisol into the blood for no reason. Movement, even a little, every day, makes the muscles drink glucose out of the blood without needing much insulin at all, which is the single most direct way a young person can keep insulin low and the growth signal quiet.
I want to be careful and honest here, because the tradition is dishonoured by exaggeration. Chanting does not cure cancer. Pranayama does not replace an endocrinologist, and a sadhana does not undo a syndrome by itself. What the practice can do is real and worth naming exactly. It can lower the chronic stress load that keeps cortisol and sugar high. It can improve the tone of the nervous system that governs the whole fuel economy. It can build the daily rhythm in which a body is occasionally allowed to run lean and burn its own fat. It can, drop by drop, return some of the metabolic flexibility that modern life quietly takes. What it cannot do, it does not pretend to do. That honesty is the tradition at its strongest.
There is a word worth keeping from all of this, and the word is resilience. It is the third of the three things this practice is built to give, alongside the tradition it comes from and the happiness it points toward. Resilience is not toughness. It is flexibility under change. A reed survives the flood that snaps the rigid tree. A metabolism that can switch fuels survives a lean week, a hard night, a long stretch of stress, that would leave a sugar-only body shaking and reaching for the nearest sweet thing. The resilient body is the flexible one. The free one. The one that does not panic when the blood runs low, because it knows how to feed itself from within.
This is, in the end, a kind of freedom that has very little to do with food and almost everything to do with how you have chosen to live in your own body.
So go back to the photograph. A body, lying still in the dark, lit from inside. On a sick body the brightest thing is the part that has lost its way, the cell that grabs all the sugar and burns it in fear. But the same camera, pointed at the same kind of organ in a body that has kept its flexibility, finds something steadier. A furnace that takes what it is given, burns it cleanly, and goes quiet between meals, content to feed on its own reserves until the next dawn.
You get to decide, across this decade, which of those bodies you are building. Not through one heroic act, and not by next month. A little, daily, drop by drop, the way the rishis built everything that lasted. The morning met with breath instead of sugar. The body allowed, sometimes, to be hungry. The nervous system taught that the day is not a threat.
The only miracle in the world is you standing on your own two feet.
Hari Om Tat Sat.
Arjun is a practitioner in the Bihar School of Yoga tradition. He founded OMJOOMSUH in 2022 as a wellness platform rooted in the Vedic sciences. The Morning Mantras practice runs live, Monday through Friday, at 6:10 AM IST.