TIME Diet/Nutrition

Eating Junk Food Changes Your Cravings

What unhealthy foods do to your palate

Junk food doesn’t just make you fat (though it does a great job of that). It might also make you boring to eat around.

That’s what a new study published in Frontiers in Psychology suggests. The research team was interested in how a “cafeteria diet”—one loaded with cheap, high-calorie food—affects the animals’ natural preference for novelty.

“Exposure to this Western diet appears to change the way the brain responds to these cues,” says study author Margaret Morris, professor at the University of New South Wales. “Their ability to discriminate what they’d just eaten is impaired, and we think that might contribute to overconsumption…if you don’t remember what you just had, maybe you keep eating.”

Two groups of rats were fed different diets for two weeks. One group was given low-fat rat chow, while the other group had its choice of the chow plus a buffet of fatty junk foods, like cookies, dumplings, and cake.

After two weeks, the junk food rats got fatter and more blasé.

Humans and animals have a natural preference for novelty, says Morris. This notion of “sensory-specific satiety” is one we’re all familiar with: if you crush a bowl of pasta and are then offered a choice of steak or more pasta, you’ll choose the steak because you’re sated on the pasta front and crave something different.

But after the rats chowed down for two weeks, researchers tested this response. They let the rats binge on either a cherry or grape Kool-Aid drink and then offered them a choice between the two flavors a couple hours later. Rats on the healthy chow consumed more of the flavor they hadn’t just binge-drank. But the junk food rats drank the same amount of both beverages. Even after researchers put the junk food rats on an all-chow diet for a week, the rats continued to show no preference for one drink over the other, “which suggests that there’s something going on in the brain of the animal that persists beyond the exposure to that unhealthy diet,” she says.

Results of rat studies don’t necessarily translate to humans, and research is mixed about whether sensory-specific satiety or memory is impaired in obese people. But at the risk of losing your taste for variety, you might consider skipping the junk food aisle.

TIME Brain

Erasing Bad Memories May Soon Be Possible

Blank photo
Getty Images (1); Illustration by Mia Tramz for TIME

Using state of the art laser and gas techniques, scientists working with mice make stunning breakthroughs in turning bad memories into better ones

Memories are a complex combination of objective information—the color of a car, the size of a building—and less tangible emotional feelings, like fear, anxiety, joy, or satisfaction. But to scientists, memories are nothing more than a series of chemical and physical changes, the firing of a nerve here, which sends electrochemical impulses to another nerve there, which together encode everything that we associate with a memory.

But exactly what do those changes look like? And is it possible to override them? In a milestone paper published in the journal Nature, scientists may have provided some answers, explaining how emotional baggage gets attached to memories, and how that can be manipulated to quite literally turn bad memories good. In separate work appearing in the journal PLOS ONE, researchers say that a commonly used anesthetic gas, xenon, if administered at exactly the right moment, can also strip the painful and negative feelings associated with a traumatic memory, essentially neutralizing it.

The findings from both groups come from mouse studies, but the two teams are confident that the results will further efforts to understand and find new ways to treat depression and post traumatic stress disorder in people.

In the Nature study, Susumu Tonegawa and his team showed for the first time exactly where in the brain both positive and negative memories are created, and how these emotional layers can be switched around. They exploited a cutting-edge technique they developed called optogenetics to track an emotional memory as it’s made and also manipulated in the brains of mice. They studied both positive experiences—male mice were allowed to spend about an hour with female mice—and negative experiences—the mice were given mild foot shocks.

MORE: 5 Secrets to Improve Learning and Memory

First, the researchers administered a protein, called channelrhodopsin, into mice nerve cells that were activated during and immediately after those experiences (the positive and the negative). The protein reacts to a specific blue wavelength of laser light—and the scientists discovered that when that light was administered to the the part of the mouse’s nerve cells that fired up after those good or bad experiences, the emotion associated with the memory was relived as though it were happening all over again, even absent the stimulus that created it in the first place.

“Optogenetics for the first time allowed us to pin down the cells in the brain that literally carry the information for a specific memory,” says Tonegawa.

The real revelation came when the scientists tested how malleable the connection between the shock and the memory was. They allowed the shocked mice to spend time with females while their brains were hit with the blue light—which triggered their fear of the shock even though they didn’t get one. After 12 minutes of the laser exposure, the mice relaxed. But it wasn’t that they had replaced their fear with more pleasant feelings. Images of their brains showed that new circuits, presumably the ones associated with more positive feelings of being with females, had sprouted between the emotional regions of the brain and the memory center. Likewise, the mice that had had the pleasurable experience with their female counterparts were given the shock while exposed to the blue light, and now showed more fear and anxiety. The original emotional associations were not eliminated and replaced. Instead, says Tonegawa, the positive and negative circuits compete with each other, and whichever is dominant becomes the prevailing emotion linked to a memory.

MORE: This Is the Brain Circuit That Makes You Shy

That could explain how some psychotherapy currently works. To help depressed patients address their feelings, some therapists will revisit negative or emotionally painful experiences. Because memories are not recalled and returned in exactly the same way like a recording, any new information attached to that memory—such as more neutral or positive perspectives about the episode—can help to diffuse its negative impact. Tonegawa’s work in animals suggests that it’s possible to make that psychotherapy technique even more effective if therapists can help patients to focus on more positive feelings while reconsolidating painful memories.

That’s what another group, at McLean Hospital, is hoping to do with a much more simplistic strategy. Edward Meloni, an assistant professor of psychiatry at Harvard Medical School and Marc Kaufman, director of the McLean Hospital Translational Imaging Laboratory, found that the gas xenon, which is used in anesthesia (primarily in Europe), can neutralize the fear associated with a traumatic memory. Exposing mice that had experienced foot shocks to the gas dramatically reduced their fear behaviors – such as freezing up and avoiding areas associated with the painful shock – for up to two weeks. That’s because xenon preferentially targets certain receptors, called NMDA, on brain nerves that are concentrated in learning and memory regions. So when a traumatic memory is activated, those neurons involved in recalling that memory are prime targets for xenon, which blocks the cells from making their usual connections to the emotional hub in the brain known as the amygdala. “My speculation is that xenon lessens the impact of the emotional component, the real emotional pain associated with a traumatic experience,” says Meloni.

MORE: Memories Can Now Be Created — And Erased — in a Lab

It’s not clear yet whether the gas will have similar effects on long-standing traumatic memories such as those involved in PTSD, but Kaufman and Meloni plan to set up a human trial as soon as possible. Ideally, says Meloni, if xenon proves to be effective and safe for reshaping memories, patients who experience debilitating nightmares would be able to give themselves a squirt of xenon just as they would use an asthma inhaler. Since the gas dissipates quickly, so far there doesn’t seem to be a reason to worry about other potentially harmful effects on the brain.

And what about situations that don’t quite reach the level of PTSD, but are traumatic nonetheless, such as the death of a loved one or a bad breakup? “In general I think those painful experiences are probably not going to be impacted by xenon because there really isn’t a specific memory that is reactivated, like a flashbulb moment of trauma,” he says. “It’s more a global heartbreak.”

Because xenon isn’t specific to blocking the negative connections to the brain’s emotional nexus, Kaufman says it’s possible the gas could also be helpful in reducing the highs and the reward sensation associated with addiction. More studies will need to show that xenon could play a role in those situations as well, but both he and Meloni are optimistic. “We’ve got a good start in animals, and as we work through the ladder in getting it to people, I’m hopeful,” says Meloni.

TIME Infectious Disease

Here’s How Ebola Spread in the Democratic Republic of Congo: WHO

A suspected Ebola outbreak in the Democratic Republic of Congo may have no connection to the outbreak in West Africa

On Tuesday, the Democratic Republic of Congo reported to the World Health Organization (WHO) that the country is having an outbreak of Ebola, which appears to be separate and unrelated to the outbreak in West Africa.

According to the information given to the WHO and provided to media, here’s how it spread: The first person to contract Ebola in the Democratic Republic of Congo was a pregnant woman who butchered a bush animal given to her by her husband. She was taken to a clinic after she started displaying symptoms of Ebola virus disease and died on Aug. 11 of a hemorrhagic fever, that at the time, was not yet identified as Ebola. The woman died, and was dealt with by health care workers.

The health care workers who cared for the woman, which included one doctor, two nurses, a hygienist and a ward boy, all developed similar symptoms and died. Similar deaths were discovered among relatives of the first pregnant woman, people who were in contact with the health care workers, and people who were involved in the burial process of all the men and women who died. According to the WHO, from July 28 to August 18 there have been 24 suspected cases of the disease there, which includes 13 deaths.

Currently, samples of those infected are being tested for Ebola.

The Democratic Republic of Congo Ministry of Health is currently monitoring the situation and is undergoing contact tracing with support from WHO.

TIME Obesity

This Is What Weight Loss Does To Your Brain

Brain scan, MRI scan
Getty Images

New research shows weight loss surgery can reverse the negative effects body fat may have on the brain

Too much fat weighs down not just your body, but also your brain.

Obesity harms most organs in the body, and new research suggests the brain is no exception. What’s more, the researchers found that getting rid of excess fat actually improves brain function, reversing the ill effects of the extra weight. The new study, which focused on people who underwent bariatric surgery, found that the procedure had positive effects on the brain, but other research has shown that less invasive weight loss strategies, like exercise, can also reverse brain damage thought to be related to body fat.

Here’s why that matters: Obese men and women are estimated to be about 35% more likely to develop Alzheimer’s compared to people of a normal weight. Some research suggests that body fat ups the number of proteins in the brain that trigger a cascade of events that predispose someone to the disease, and other research in mice has suggested that fat cells release a substance called interleukin 1, which can cause severe inflammation and, in turn, gunk up the brain.

In a recent study, a team of researchers looked at 17 obese women prior to bariatric surgery and found that their brains metabolized sugars faster than the brains of a control group of women at a normal weight. The women underwent cognitive function tests before their surgery as well as after. The results show that after surgery, the obese women showed improvement in the troubling brain activity seen prior to going under the knife, and they performed better on their cognitive function tests—especially in the area of executive function, which is used during planning and organization. The findings suggest that the fat loss reversing its bad effects on the brain.

It is possible that the long-term “cerebral metabolic activity”—meaning the way the brains of obese people process sugars—leads to structural damage that can hasten or contribute to cognitive decline, the authors write in their paper.

Researchers are still trying to understand the exact effects of body fat on the brain, but one theory is that it’s a chain-of-events-type of scenario. For instance, insulin resistance has become linked to neurodegenerative diseases like Alzheimer’s because insulin resistance is associated with an increase in fatty acids, inflammation and oxidative stress. Insulin resistance is a metabolic disorder, that can be brought on by obesity. Other theories have to do with the effects of certain kinds of fat. The National Institutes of Health (NIH) points out that visceral fat, the most damaging type of body fat, ups a person’s likelihood of developing insulin resistance, and on top of that, belly fat can produce stress hormones that can also hinder cognition. Other research has shown that the stress hormones are tied to hunger signaling, and those disruptions can alter a person’s sense of hunger and fullness and can contribute to obesity.

“The more we understand about [body fat], the clearer it becomes that belly fat is its own disease-generating organism,” said Dr. Lenore Launer, chief of NIA’s Neuroepidemiology Section of the Laboratory of Epidemiology, Demography, and Biometry in an NIH statement.

Inflammation continues to be fingered as a culprit in the link between body fat and a variety of disorders, which include brain-related diseases, and even depression. Body fat, also referred to as adipose tissue, is thought to create substances that cause inflammation, and that could be at least one of the primary ways it irritates the brain.

The bottom line is that excess body fat has a laundry list of effects on the body, and none of them are good. But on the bright side, getting rid of that fat should reverse some of the blips body fat is leaving on the brain. Though not everyone needs to go under the knife.

TIME Television

Watch Homer Simpson Take the Ice Bucket Challenge

D'oh!

+ READ ARTICLE

Homer Simpson is jumping on the Ice Bucket Challenge bandwagon.

The clip parodies the movement that’s dominated social media in recent weeks, in which people dump ice water on themselves to raise money and awareness for research into ALS, or Lou Gehrig’s disease.

Homer dumps a tiny cup of water on himself and pretends to suffer: “But it was all worth it to raise awareness for ALS.” But then his kids raise the stakes, finding something a bit more frigid to dump on Homer.

TIME health

5 Workout Moves That Will Change Your Body

runner
Getty Images

Functional training gives you the kind of strength that matters at the end of the day. This type of training will give you power in your daily life for practical movements like hauling your cooler to the beach, moving furniture, or carrying a toddler. So instead of measuring your strength by how much weight you can bench press (or curl, or squat), get fit where it counts by doing exercises that stem from natural, everyday movements like bending, pushing, and twisting.

Try this 5-move functional workout to feel the power, fast!

  1. T Push-up

Start in push-up position with your hands directly beneath your shoulders. Lower into a push-up, and as you return to starting position, rotate your torso to the left raising your left arm up into the air so that you are in a T position. You will need to engage your core, and balance on your right hand and sides of your feet. Hold this position for a count of two, and return to push-up position. Repeat, next time twisting to the right side and raising your right arm. Complete 3 rounds of 8 push-ups.

Health.com: How to Do the Perfect Push-Up

  1. Squat with Overhead Press

Stand hip-width apart holding two dumbbells at your shoulders. Squat down until your knees are bent at a 90-degree angle, keeping your weight back on your heels. Your torso should bend forward slightly with your knees tracking over your feet, without going past them. As you come back to standing, press the dumbbells up over your head to a full extension. As you lower back into another squat, lower the weights back down to starting position. Repeat for 3 rounds of 10 squats with overhead presses.

Health.com: How to Do a Squat with Perfect Form

  1. Reverse Wood Chop with Dumbbell

With your feet in a wide stance and knees slightly bent, hold a dumbbell in both hands by your right hip. From here, rotate your torso and engage your abs to bring the dumbbell up to your left shoulder in a fluid motion. Lower the weight back down and repeat. Remember to keep your abs engaged even as you lower the weight. Repeat for 3 rounds of 10 on each side.

Health.com: 24 Fat-Burning Ab Exercises (No Crunches)

  1. Hip Extension with Reverse Fly

This exercise will test your balance while working your back, shoulders, and legs. Stand with your weight on your right foot, holding a light dumbbell in each hand at your sides. Keeping your body in a straight line, lean forward while bringing your left leg out in a straight line behind you. As you lean forward, raise your arms out to the side into a T position. Your chest should be parallel to floor with your leg in a straight line. Hold for a count, and return to neutral. Repeat for 3 rounds of 10 on each leg.

Health.com: 11 Moves to Get Strong, Toned Arms

  1. Russian Twists

This move will work your obliques and also test your balance. Sit on your butt with your knees bent and feet flat on the ground, holding a dumbbell with both hands. Lean back so that your torso is at a 45-degree angle to the floor. (If you’re more advanced, lift your feet off the ground and cross them at the ankles while balancing on your butt.) From this position, rotate your torso to the left and touch the dumbbell to the ground next to your body. Next, twist back over to the right tapping the weight to the ground on the right side of your body. That’s one rep. Repeat back and forth all while balancing, moving as quickly as possible. Repeat for 3 rounds of 20 twists.

This article originally appeared on Health.com.

TIME Mental Health/Psychology

You Asked: What’s the Best Bed Time?

Illustration by Peter Oumanski for TIME

The earlier the better? 11 PM? Sundown? Sleep experts say it’s not that simple. But there is a time range you should shoot for if you’re questing for a perfect night’s sleep

Every hour of sleep before midnight is worth two after midnight. Your grandparents (and great grandparents) probably adhered to that creaky adage. “The mythology is unfortunate, because there’s no pumpkin-like magic that occurs,” says Dr. Matt Walker, head of the Sleep and Neuroimaging Lab at the University of California, Berkeley. And while nothing special happens to you or the quality of your sleep at the stroke of midnight, many do wonder: What’s the best time to go to bed?

Walker says your sleep quality does change as the night wears on. “The time of night when you sleep makes a significant difference in terms of the structure and quality of your sleep,” he explains. Your slumber is composed of a series of 90-minute cycles during which your brain moves from deep, non-rapid eye movement (non-REM) sleep to REM sleep. “That 90-minute cycle is fairly stable throughout the night,” Walker explains. “But the ratio of non-REM to REM sleep changes.”

He says that non-REM sleep tends to dominate your slumber cycles in the early part of the night. But as the clock creeps toward daybreak, REM sleep muscles in. That’s significant, because some research has suggested that non-REM sleep is deeper and more restorative than lighter, dream-infused REM sleep—though Walker says both offer important benefits.

What does this have to do with the perfect bedtime? The shift from non-REM to REM sleep happens at certain times of the night regardless of when you go to bed, Walker says. So if you hit the sack very late—at, say, 3 AM—your sleep will tilt toward lighter, REM-heavy sleep. And that reduction in deep, restorative sleep may leave you groggy and blunt-minded the next day.

That’s unfortunate news for nightshift workers, bartenders, and others with unconventional sleep-wake routines, because they can’t sleep efficiently at odd hours of the day or night, Walker says. “The idea that you can learn to work at night and sleep during the day—you just can’t do that and be at your best.” Your brain and body’s circadian rhythms—which regulate everything from your sleeping patterns to your energy and hunger levels—tell your brain what kind of slumber to crave. And no matter how hard you try to reset or reschedule your circadian rhythms when it comes to bedtime, there’s just not much wiggle room. “These cycles have been established for hundreds of thousands of years,” Walker explains. “Thirty or 40 years of professional life aren’t going to change them.”

When it comes to bedtime, he says there’s a window of a several hours—roughly between 8 PM and 12 AM—during which your brain and body have the opportunity to get all the non-REM and REM shuteye they need to function optimally. And, believe it or not, your genetic makeup dictates whether you’re more comfortable going to bed earlier or later within that rough 8-to-midnight window, says Dr. Allison Siebern, associate director of the Insomnia & Behavioral Sleep Medicine Program at Stanford University.

“For people who are night owls, going to bed very early goes against their physiology,” Siebern explains. The same is true for “morning larks” who try to stay up late. For either type of person—as well as for the vast majority of sleepers who fall somewhere in between—the best bedtime is the hour of the evening when they feel most sleepy.

That means night owls shouldn’t try to force themselves to bed at 9 or 10 if they’re not tired. Of course, your work schedule or family life may dictate when you have to get up in the morning. But if you can find a way to match your sleep schedule to your biology—and get a full eight hours of Z’s—you’ll be better off, she adds.

Both she and Walker say your ideal bedtime will also change as you age. While small children tend to be most tired early in the evening, the opposite is true for college-aged adults who may be more comfortable going to bed around or after midnight. Beyond college, your best bedtime will likely creep earlier and earlier as you age, Walker says. And again, all of this is set by your biology.

Siebern suggests experimenting with different bedtimes and using sleepiness as your barometer for a best fit. Just make sure you’re rising at roughly the same time every morning—weekdays or weekends. It’s fine to sleep an extra hour on your days off. But if you’re getting up at 6:30 during the workweek and sleeping until 10 on weekends, you’re going to throw off your sleep rhythms and make bedtime more challenging, she says.

TIME Infectious Disease

Ebola Forces the WHO to Shut Down Its Lab in Sierra Leone

Relatives of an Ebola victim mourn in Lango village, Kenema, Sierra Leone on Aug. 25, 2014.
Relatives of an Ebola victim mourn in Lango village, Kenema, Sierra Leone on Aug. 25, 2014. Mohammed Elshamy—Anadolu Agency/Getty Images

Medical workers are in retreat as the deadly virus continues to ravage West Africa

The World Health Organization (WHO) announced Tuesday that it had shut down an Ebola-testing laboratory in Sierra Leone and pulled its staff, after a health worker contracted the lethal virus, Reuters reports.

“It’s a temporary measure to take care of the welfare of our remaining workers,” WHO spokesperson Christy Feig told the news agency. She did not specify how long the closure would last, but said staff would return “after our assessment.”

The lab is located in Kailahun, an area near the Guinean border that is severely affected by the outbreak, but it is unclear precisely how the infected worker, an epidemiologist from Senegal, contracted the virus. The WHO said he would be evacuated out of the country for treatment.

“The field team has been through a traumatic time through this incident,” said Dr. Daniel Kertesz, the WHO representative in Sierra Leone, in a statement. “They are exhausted from many weeks of heroic work, helping patients infected with Ebola. When you add a stressor like this, the risk of accidents increases.”

The shuttered lab is one of only two in the country, Reuters says, and its closure is likely to impede efforts to contain the deadliest ever outbreak of the virus, which has infected at least 2,615 people and killed at least 1,427.

Reuters also reports that Canada has pulled its three-person mobile laboratory team from Kailahun. Sean Upton, a spokesperson for the Public Health Agency of Canada, said on Tuesday that the workers were brought home because three people staying at their hotel had contracted Ebola. He added that the Canadian medics did not have contact with the infected individuals and did not display any symptoms of the virus.

Meanwhile, a spokesperson for Doctors Without Borders told the New York Times that it would continue to operate an 80-bed treatment center in Kailahun.

Health workers have paid a heavy price in their efforts to contain the outbreak, which has killed at least 120 medical workers and infected more than 240 as of Monday.

TIME Innovation

Ralph Lauren Debuts Biometric Shirts at the U.S. Open

Fashion-Wearable Tech
Ralph Lauren's new garment offers smart technology to send heartbeat, respiration, stress levels and other data to tablets and smartphones AP

But don't get excited. You won't be able to buy them until early 2015

Fashion guru Ralph Lauren has sought to morph fashionable sportswear into wearable technology with the launch of the Polo Tech smart shirt, which is being worn by some ball boys at this year’s U.S. Open tennis tournament.

The compression garment comes with technology from a Canadian firm, OMsignal, that feeds detailed information about a wearer’s heart rate, breathing, activity and so on directly to a smartphone or tablet.

Silver-yarn-based sensors gauge athletic performance by measuring the expansion and compression of the wearer’s chest along with electrical changes associated with heart rate. The information is collected in a small black-box-type recorder, which can be removed when the garment needs to be thrown into the washing machine.

While the Polo Tech shirt is making a splash at the U.S. Open, the public won’t be able to purchase it until the spring.

TIME India

India Just Asked PepsiCo to Help Improve the Diet of the Nation’s Children

Indra Nooyi Meets Minister Harsimrat Kaur Badal
PepsiCo CEO Indra Nooyi, right, meets Food Processing Minister Harsimrat Kaur Badal in New Delhi on Aug. 26, 2014 Saumya Khandelwal—Hindustan Times/Getty Images

Wait, aren't they the people who make Doritos and Mountain Dew?

India’s government is soliciting the help of an improbable partner in improving the nutrition of millions of its hungriest children, reports Bloomberg. That partner is the world’s largest snack producer, PepsiCo.

Food Processing Minister Harsimrat Kaur Badal met PepsiCo CEO Indra Nooyi on Tuesday to discuss the possibility of developing nutritious processed foods for use in school lunches across the country, Bloomberg says. The move is part of Prime Minister Narendra Modi’s goal of upgrading the diet of the South Asian nation’s 1.2 billion people — especially that of its 440 million children.

“I suggested [that PepsiCo develop] products which will be healthy and will also contain proteins,” Badal told reporters following her meeting. “As people are becoming busy, the children will be immensely benefited if such products are launched.”

India has a poor reputation when it comes to food safety. A nadir was reached last year when 23 children in the country’s northern state of Bihar died after eating a free school meal that turned out to be laced with pesticide. In addition, some 47% of Indian children under 3 are underweight, according to the U.N.

Critics wonder if processed foods, from a company better known for its sugary soft drinks and potato chips, are really the best way to address such chronic malnutrition.

“No respectable dietitian or nutritionist will recommend processed foods over freshly cooked meals,” Vandana Prasad, national convener of the Public Health Resource Network, told Bloomberg.

PepsiCo India did not reply to Bloomberg’s emailed questions about the meeting.

[Bloomberg]

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