Teresa was determined to help her husband overcome obesity—the greatest threat to his health. Following Professor Richard’s suggestion, she would eventually turn to the issue of hormonal imbalance, but first she wanted to understand whether something was wrong with his digestive system.

She and Mark lived in the same house, drank the same water, ate the same food. If there was an external chemical agent contributing to obesity, Teresa would have been exposed to it as well. Mark was not taking any regular medication either. And it was not just him—hundreds of people in the town of a few thousand were obese. Teresa considered it carefully and tried to identify a common factor linking so many people. She thought of gender, ethnicity, and even dietary habits shaped by religious rules about lawful and forbidden foods, but she could not find a single unifying element.

She murmured to herself:
“This sudden rise of obesity might be a coincidence, or maybe something caused these people to weaken in willpower and lose control over their appetite. But I know these people. They are not careless, impulsive individuals who ignore the future. They are people who show moral strength, who uphold ethical, religious, and universal values. Not just Mark—none of them are reckless or indifferent to life.”

Convinced that the issue was not a matter of weak character, Teresa sighed and began her research on hormones. She started with a book that explained basic medical concepts through storytelling—a style that suited her own way of thinking.

“Hormones are, in the literal sense of the word, couriers. Just as the hemoglobin in red blood cells carries oxygen from the lungs through the aorta, branching arteries, and finally through capillaries to even the most remote cells of the body—and then returns with carbon dioxide so it can be expelled in the lungs—hormones carry chemical messages throughout the body. Like red blood cells acting as couriers for oxygen and carbon dioxide, hormones serve as couriers for countless chemical signals. Their journey times vary, as do their size, chemistry, and the effects they produce.”

What captured Teresa’s attention most in the text was this idea:
“Due to changes in gut flora, the receptor sites of target cells for insulin may become dysfunctional. In that case, insulin cannot recognize its destination and fails to bind to its target cell.”

She wondered if a similar process might be occurring in Mark. Perhaps a hormone was not being secreted at all, or—if secreted—was unable to reach its target, leaving its intended function unfulfilled. Yet according to Mark’s test results, neither his blood, urine, nor fecal flora showed abnormalities. These results suggested no overgrowth of microbes and no disruption in the body’s natural microbial balance.

Teresa could not draw a clear conclusion from what she read, but she tucked the information away—knowing that knowledge often lies dormant until the moment it suddenly matters. A body grown old, a spirit still young, she continued reading.

“An imbalance in cortisol levels disrupts blood pressure, but its most tragic effect is the increase in psychological stress. When cortisol imbalance is severe, a person may not only fall into deep depression, but may even be pushed toward suicide. That is why an experienced psychiatrist will first look at cortisol levels in a blood test. Beyond its psychological influence, cortisol governs countless vital processes…”

Mark had no particular issue with stress; he only became irritable when he didn’t eat, but once he began bringing food to his mouth, there was no trace of unhappiness. For that reason, the common saying, “I eat a lot when I’m stressed,” did not apply to him, although Teresa mentally noted the fact that cortisol, stress, and pathological overeating could indeed be linked in some individuals.

The ringing phone pulled Teresa out of the world of hormones. When she saw Professor Richard’s name on the screen, she understood that the results were in. The moment she answered, the professor began without pleasantries:

“The lab sent the report to me first because they detected some unusual toxic substances.”

Naturally, Teresa’s anxiety and curiosity surged. She managed only:
“I’m listening.”

“All values were normal except for a hormone called ghrelin and a chemical,” he began.

“It’s well established that thyroid hormones are connected to appetite regulation. His thyroid levels are normal. But ghrelin — whose existence and link to hunger have only been understood in recent years — was measured above the reference range. Yet there are things we don’t fully understand about this hormone. Does ghrelin cause hunger, or does hunger trigger ghrelin secretion? We still don’t know. So simply blaming ghrelin for Mark’s obesity would be premature.”

“But,” Teresa interjected,
“Mark gave his blood sample while he was full — at a time when he shouldn’t have been experiencing hunger at all.”

After a brief silence, the professor replied:

“Yes. That does suggest that ghrelin may be responsible for Mark’s persistent hunger. With medication or even a surgical intervention, we could theoretically suppress its secretion. But the thing that truly concerns me is the foreign chemical that was detected.”

“And this chemical — doesn’t it have a name, a form?”

“The elements, molecules, and the quantity composing it are known, but as I said, this chemical does not match any of the natural or synthetic compounds recorded in the laboratory database. And that database is constantly updated with internationally accepted research. The fact that this compound is absent from it is… curious. But I’ll keep investigating.”

Teresa’s initial shock had passed; she recovered quickly and asked:
“Even if the chemical has no name, can’t we still determine what kind of effect it has?”

“Teresa, your hair may be white, but your mind is still young,” the professor said with a smile, before continuing.

“Yes, that is precisely what I want to emphasize. There is another hormone we’ve only known about for five to ten years. However, only advanced university biochemistry labs can measure its level in the blood using a specific method. The hormone I’m referring to is leptin. You know the expression ‘I’m hungry like a wolf’? Experts would say that the blood of someone who says that contains very little leptin.

When this hormone was first discovered, researchers thought it could be used to treat obesity. From what I recall, it worked in animal experiments, particularly in mice, but clinical trials with volunteer obese individuals did not produce the expected results.”

“I was about to say, ‘We’ve found the culprit,’ but now you’re telling me the high leptin trials didn’t work on volunteers.”

“I told you earlier that your neurons were young; I may have been mistaken. They’re ageing a bit,” Professor Richard replied with a faint laugh.

“What we are trying to understand right now is why Mark gained weight so rapidly and became obese. Reducing him to a normal weight is our second objective.”

“All right, professor, I understand,” said Teresa.

“With high leptin levels in the blood, a person’s desire to eat can be suppressed, but by altering the level of leptin you cannot directly make an already obese person lose weight. At most, by reducing appetite, you may help them lose weight indirectly. So the real question is: is Mark’s leptin level low or high?”

“That,” said Professor Richard, “is the critical question.”

“Mark’s blood sample showed an extremely low level of leptin — not just low, but almost absent. What I’m saying is, that unnamed chemical we mentioned earlier is somehow blocking the secretion of leptin.”

“How could that even happen? How did this chemical enter Mark’s bloodstream?”

“Leptin-related research is still at a clinical stage. There is no approved medication based on this hormone, and nothing is legally available in the market. The World Health Organization has not authorized anything of the sort. Which is why I wanted to ask you the same question: if leptin itself cannot be sold as a drug, how did a compound that blocks its secretion end up in Mark’s blood?”

There was no answer. The professor and Teresa were thinking about how to eliminate the chemical from Mark’s system. They had tried everything. They changed the grocery store they shopped at, the water they drank, the food they ate — even the air they breathed by moving to another town. Yet no matter what they did, nothing changed.

Teresa was on the verge of losing her mind. She had the hormone levels measured before meals, after meals, during the day, at night, on weekdays, on weekends — every possible timing that might influence secretion. But the results were always the same: Mark’s leptin had vanished. The values remained close to zero, even though there was nothing abnormal in the fat cells that were supposed to produce the hormone.

The unanswered question echoed in Teresa’s neurons:
“How can a nameless chemical continuously infiltrate Mark’s blood… unless Mark is the production center of that chemical?”

She forced herself to think calmly, again and again, until one possibility emerged.
She reached out to other obese people in town and asked them to have their leptin levels tested — along with the foreign substance she labeled “Chemical X.”

The results were exactly as she expected. Just like Mark, their leptin levels were nearly nonexistent, and Chemical X was present in their blood.

It made no sense to believe that isolated mutations had occurred in certain individuals, causing chemical imbalances that led to obesity. If someone had deliberately caused Chemical X to enter the blood of the town’s obese population, then who would do such a thing — and what could they possibly gain from it?

She recalled the days when she had exposed fringe organizations and saboteurs, dismantling their plans before they could materialize. She wondered if one of them might now be seeking revenge — but if that were true, she should have been the target, not Mark. She had wounded them more than they had ever wounded her. Besides, among the town’s obese, there were people of different faiths, nonbelievers, and those with conflicting political views.

“Be realistic,” she muttered to herself. “Not everything has to be blamed on some secret, unknown organization. Drop the conspiracy theories.”

As she thought, her eyes drifted to the credit card statement on the table. Seeing that the number had climbed into five digits instead of four made her clench her jaw.

“Great. Over ten thousand dollars. What the hell did we even buy?” she grumbled. The itemized list shifted constantly, but two names never changed: the town’s only burger joint, and the large supermarket.

The possibility that crossed her mind sounded absurd, but she couldn’t dismiss it.

“No. Come on. Don’t tell me the burger guy and the supermarket owner used Chemical X so that people would eat more, shop more, and spend more money.”

A different voice inside her answered:

“Why not? Worse things happen every day. In a capitalist world, corporations pump the market with carcinogens, modified foods, and toxic chemicals just to earn more. Why would they hesitate to use a chemical no one has ever heard of? And if the damage is ever revealed, their excuses will be ready:

We didn’t know. How could we have predicted obesity? And if that doesn’t work, they’ll buy a couple of scientists to publish a study claiming that Chemical X has nothing to do with obesity. You know perfectly well they’ve done this before — and succeeded. If I started telling you about the tricks and frauds of pharmaceutical companies…”

Teresa was certain that the voice within her wasn’t some trivial whisper of paranoia, but a rational explanation arising from her own mind. The scientist in her had now zoomed her focus onto the town’s largest supermarket and the hamburger joint. She frequently passed by both establishments, discreetly observing the employees. To understand whether the burger place used anything beyond the known chemical-laden products like ketchup and mayonnaise, she would scan the surroundings quickly without drawing attention.

The chef, noticing her glance, assumed she was just another hygiene-obsessed customer.
“Come, come — you’re welcome to tour the kitchens if you like. We care a great deal about health and hygiene,” he said, handing her a framed certificate hanging on the wall.
“This year’s award from an independent inspection agency.”

Teresa could sense his sincerity. She didn’t want to step into the kitchen and attract even more attention, or worse, alert the owner. If the man realized someone suspected him, he might destroy evidence like any criminal cornered.

“I know this place has high standards,” she said. “I just thought I recognized one of your staff — an old friend, but then I remembered he couldn’t possibly be here.”
The chef simply replied, “As you wish,” and walked away.

And they call me the old wolf who’s still got her sharp instincts, she thought. I almost let him figure out what I was after.
To keep up appearances, she bought several burgers on her way out. The chef already knew her — the only difference was that this time, the large fellow always beside her, Mark, wasn’t with her.

Outside the supermarket, Teresa saw that the place was buzzing like a beehive. Among those entering and leaving were not only overweight people, but thin, healthy-looking individuals.
She paused, thinking. The customers weren’t being specially encouraged to buy anything. The discounted items were familiar foods with known ingredients. And those slim people — just like her — shopped here too. If Chemical X was present, it should have entered their bodies as well. Yet neither she nor other thin individuals had shown traces of it in their blood.

The hamburger joint might selectively lace food with X, slipping it between mayonnaise, ketchup, meat, or bread — perhaps only for certain customers. But in a supermarket that sold sealed products, that seemed impossible.

Her thoughts were cut short by the ringing of her phone. Seeing Professor Richard’s name on the screen, she felt a spark of excitement.

“Yes, Professor,” she answered. “I’m listening.”

“Don’t lose hope,” the professor said, easing into his explanation.
“I managed to track down some of the pharmaceutical companies that worked on leptin. As I mentioned before, they realized it couldn’t be used as an effective obesity treatment. Nor did they reach any conclusive results on whether it could suppress uncontrolled eating. So they discontinued their work—or pretended to. But I’ve continued the investigation quietly with a few trusted colleagues, because I’ve heard certain rumors.”

“What did you hear, Professor? Tell me.”

“No, Teresa. I’m a scientist. I won’t poison your mind with unverified information or cast suspicion on people or institutions without solid evidence. My colleague and I are investigating, but we’ll need a few weeks.”

“Perhaps I could help,” Teresa insisted.

“I highly doubt it. This isn’t one of your demons-and-mysticism cases. Let me just say this much: a company involved in bacteria-related ventures.”

“All right. You know best. I don’t know a thing about antibiotics,” Teresa replied, ending the call.

On the other end, Richard muttered to himself,
“When people hear bacteria, they think only of antibiotics.”

Weeks passed with no word from Professor Richard. In the meantime, Teresa tried to adjust to their new home, hoping the move might solve something. She adapted quickly—that was the good news. The bad news was that Mark didn’t change at all.

He continued his old habits with renewed ferocity. Every meal ended in a second round of hamburgers, pizza, and whatever sweets he could find, devoured like a Tasmanian devil—barely chewed, swallowed whole. Worse still, Mark had begun doing things he had never done before.

In the dead of night, while half-asleep, he would raid the refrigerator and consume everything in sight. To avoid humiliating or angering him, Teresa joked the same way every morning.

“The cute little ghost haunting our new home is a selfish creature. You’d think it would leave us something to eat.”

Mark always responded to her morning joke with the same playful line:
“Let it be a little offering from us. If you provoke that cute ghost, who knows, it might turn into an evil spirit and haunt you.”

But today, he answered differently.
“Oh God, my tooth is starting to hurt.”

Teresa thought, half-ashamed of herself, Good… something is finally punishing you.

“If you shovel food into your mouth like this, of course your teeth will wear down, decay, and eventually hurt,” she said.

Mark took a painkiller, but it did nothing. The throbbing in his molar pulsed like a heartbeat, sharp and intolerable.
“But we had root canal treatment done on this tooth just two years ago.”

“It’s probably infected again. You’ll have to take antibiotics. Until the infection calms down, don’t try to chew with that tooth, or the pain will flare up again. A painkiller won’t cut it.”

“And after that?”

“We’ll ask the dentist. Most likely he’ll prescribe antibiotics twice a day for five days, and then extract the tooth immediately. Maybe he’ll suggest repeating the root canal, but they usually go for extraction. And now implants are common—they can place one right after the extraction.

But they don’t do that with infected teeth. Medically speaking, they wait because a granuloma at the tooth’s apex—the pocket of infection—can damage surrounding tissue, and the infection might still be lingering in the jawbone.”

“Whatever,” Mark grumbled.
“Let’s just go to the dentist.”