TIME medicine

This Is a Baby’s Brain on Pain

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For the first time, scientists map newborn babies’ brains on pain, and the results are surprising

In a first, researchers at Oxford University have watched infants as young as a day old as their brains process a light prodding of their feet. The results confirm that yes, babies do indeed feel pain, and that they process it similarly to adults. Until as recently as the 1980s, researchers assumed newborns did not have fully developed pain receptors, and believed that any responses babies had to pokes or pricks were merely muscular reactions. But new research published Tuesday morning changes that.

Taking advantage of the fact that newborns less than a week old tend to sleep through anything, Rebeccah Slater, an associate professor of pediatric neuroimaging at Oxford, and her colleagues placed 10 infants who were 1-6 days old in an fMRI machine. The researchers, who reported their findings in eLife, observed which areas of the infants’ brains became more active, or consumed more oxygen, as the scientists lightly poked their feet. They did the same for adults and compared the brain images.

In adult brains, 20 regions were activated by the painful stimulus, and the newborns shared 18 of these. “The infant’s brain is much more developed than I was expecting,” says Slater. “I might have thought that some information might have gone to the sensory areas of the brain — telling the baby something was happening on the foot, for example — but I didn’t necessarily think it would go to areas more commonly involved in emotional processing such as the anterior cingular cortex, which is thought be involved in the unpleasantness associated with an experience.”

Even at birth, then, a baby’s brain possesses the foundation for quickly evaluating anything he or she experiences, including painful stimuli. “I hope this provides incentive to more researchers to find better ways of measuring pain in babies, and prioritize the importance of providing the best pain relief possible in children,” says Slater.

Slater found that newborn brains are still immature in some ways, however. Any stimulus, whether it’s a painful one or a sensory one such as a smell, tends to activate widespread regions of the brain. That signals that the baby’s brain is still trying to learn what’s what and distinguish different stimuli. The poking triggered even the newborns’ olfactory system, for example, even though the sensation had nothing to do with smell.

Second, babies tend to register all stimuli as having the same intensity. Even light pokes “feel” the same as harder ones, reflecting their still inexperienced system in distinguishing levels of activation.

But the fact that they are experiencing pain in almost the same ways as adults do is very revealing. Now that there’s evidence that the brains of babies do indeed process pain, that may change the way doctors treat newborns, especially those who are premature or need extra medical attention in the neonatal intensive care unit. In a recent study, scientists tallied an average of a dozen procedures including needle sticks that babies experienced every day; more than 60% of those infants did not receive any pain medication, either in the form of a topical numbing cream or other pain relief. Having these experiences may make these babies more sensitive to pain later in life, says Slater. A study of circumcised baby boys, for example, found that those who received pain relief felt less pain when getting vaccinations three months later than those who didn’t receive any pain medication.

“Now that we have seen for the first time what is happening in babies’ brains while they experience something mildly painful,” says Slater, “there should be a big drive to try to treat pain in these children, especially those having a high number of procedures performed in their early days.”

TIME medicine

Smokers Don’t Think a Few Cigarettes Will Harm Their Health

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Nearly everyone knows that smoking is harmful for your health. But some refuse to admit that their habits may be killing them

Heart disease, lung cancer, throat cancer, diabetes—the list of bad things that smoking does to your health is long and growing longer. Thanks to public health warnings and education campaigns, most of us have heard that cigarettes can be dangerous to your wellbeing and can shorten your life.

But one group who should be getting that message loud and clear may be in a bit of denial. In a study of more than 1,600 French smokers and non-smokers, 34% said that lighting up 10 cigarettes a day would not put them at higher risk of lung cancer. And fewer than 40% knew that their risk of lung cancer wouldn’t disappear if even if they quit smoking. The results were presented at the European Lung Cancer Conference in Geneva, Switzerland.

“The fact that one third of subjects wrongly considered that a daily consumption of up to 10 cigarettes was not associated with any risk of lung cancer is particularly impressive and threatening,” writes study author Dr. Laurent Greillier from Aix Marseille University in response to questions about the findings.

The results were especially worrisome since the participants in the study were 40 years old to 75 years old and therefore spent most of their adult lives hearing strong public health warnings about the dangers of smoking. That means that while anti-smoking campaigns have been effective, they may not have educated people deeply enough about the dangers of tobacco. That’s especially true for people who engage in what they consider to be “safe” or “light” smoking, the study finds. “Our results suggest that public health policies must continue to focus on the tobacco pandemic, and notably initiate campaigns concerning the risk of any cigarette,” says Greillier.

TIME medicine

The Strange Way a Diabetes Drug May Help Skin Scars

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We all form scars, but most of us don’t want them. There may soon be a way to make them disappear

We all have them — scars that won’t let us forget the spill we took off a bike, the burn we got from a hot stove, or even the legacy of radiation therapy. Scarring is a good thing in some ways — it’s the body’s quick response to a deep injury, its way of protecting and sealing up the wound to keep infections and other noxious agents away.

Now scientists led by Dr. Michael Longaker, co-director of the Institute for Stem Cell Biology and Regenerative Medicine at Stanford University, report in the journal Science that they have teased apart the molecular steps behind scarring, and also discovered a way to inhibit them from forming.

While training to become a plastic surgeon, Longaker operated on fetuses still in the womb and became intrigued by the fact that they did not scar; any incisions surgeons made disappeared practically without a trace. Why, if babies did not change their genes from the womb to the time they are born, do infants form scars?

Working with mice, the team focused on two kinds of fibroblasts, which are cells responsible for maintaining the structural integrity of organs, tissues and more. One is primarily responsible for wound healing, and the formation of tumors like melanoma. “This type of fibroblast starts out as less than 1% of the developing skin, but by the time an animal is a month old, it’s 80% of the fibroblasts in skin on the back of the animals,” he says.

When he treated the cells with diphtheria toxin, which destroys the fibroblasts, the animals scarred less. It turns out that these fibroblasts carry a marker on their surface that helps scientists to pick them out. And even more fortuitous, there is a drug approved for treating type 2 diabetes that inhibits the work of this marker.

In the mice, the drug reduced scarring but did not compromise the integrity of the wounded skin at all, making it a promising potential treatment for scar in people. Each year in the US people get 80 million operations, the bulk of which require incisions that leave a mark, not to mention the millions more who get cuts or scrapes during accidents or who develop fibrous tissue after radiation to treat cancer. If the scar-inhibiting drug is used on those wounds before they begin to heal, says Longaker, it’s possible they won’t leave a scar.

Whether the same could be true of existing scars isn’t clear yet. But he says that doctors may be more eager to do revision surgery to minimize scars if such a compound exists. And, if the results are repeated and confirmed, doctors may be able to reduce scars not just for cosmetic purposes but for medical ones as well, such as in the heart after a heart attack, following spinal cord injury and in deep tissues treated with cancer-fighting radiation.

TIME medicine

The Scary Connection Between Snoring and Dementia

Sleep disorders, including sleep apnea and snoring, can have harmful effects on the brain over the long term

If you don’t snore, you likely know someone who does. Between 19% and 40% of adults snore when they sleep, and that percentage climbs even higher, particularly for men, as we age. It’s a nuisance for bed partners, but researchers say we shouldn’t be so quick to write off snoring or other forms of disrupted breathing while asleep as mere annoyances; instead, they could be affecting the brain, according to new research.

Snoring is a form of sleep apnea, in which people stop breathing for a few seconds or several minutes dozens of times in an hour. Any disruption of breathing during sleep can affect the brain, say researchers of a new study published in the journal Neurology. They found that people with sleep apnea tended to develop memory problems and other signs of mild cognitive impairment (MCI) earlier than people without such sleep disorders.

MORE The Power of Sleep

Ricardo Osorio, MD, research assistant professor of psychiatry at NYU Center for Brain Health, and his colleagues studied 2,000 people enrolled in the Alzheimer’s Disease Neuroimaging Initiative (ADNI)—a population of 55 to 75 year olds, some of whom are cognitively normal, some who have mild cognitive impairment and others who have Alzheimer’s dementia. Everyone was asked about their snoring or sleep apnea, and researchers followed up every six months for two to three years to record any changes in their cognitive status.

Those who reported having sleep apnea or snoring tended to develop signs of mild cognitive impairment, including memory lapses and slower speed on cognitive skills, about 12 years earlier on average than those who didn’t report any sleep-disordered breathing. Mild cognitive impairment often precedes Alzheimer’s dementia, but not all people who develop MCI go on to get Alzheimer’s. The connection between disrupted sleep breathing and MCI remained strong even after Osorio accounted for the effects of Alzheimer’s-related genes, gender, education, depression and heart disease risk factors, all of which have been associated with increased risk of cognitive decline.

MORE Alzheimer’s Linked to Sleeping Pills and Anti-Anxiety Drugs

Osorio also saw a connection between sleep apnea or snoring and Alzheimer’s dementia, but it wasn’t as robust as the link to MCI. That might be because other studies have found that not only are sleep disorders a risk factor for Alzheimer’s, but they are also a symptom of the degenerative brain disease—so those who already developed Alzheimer’s dementia may not have been accurately reporting their sleep habits.

Osorio is careful not to implicate all snoring as a precursor to memory problems or Alzheimer’s. But particularly in the elderly, he says doctors should consider the potential effect that disrupted breathing during sleep can have on the brain. While it’s not clear how sleep disorders might be increasing the risk of MCI or Alzheimer’s, it’s possible that the cumulate effects of even the short periods when the person isn’t breathing could deprive brain neurons of critical oxygen, and Alzheimer’s has been linked to slower or abnormal blood flow caused by hypertension and high cholesterol levels. Other studies have also shown that the protein responsible for Alzheimer’s, amyloid, tends to build up during the day when the nerves are active and decline at night during deep sleep. If people are being roused from deep sleep by their apnea or snoring, then they aren’t enjoying prolonged periods of low amyloid production, so the substance can build up and potentially form plaques.

MORE Here’s How Much Experts Think You Should Sleep Every Night

Osorio also found that it’s possible to counteract some of the effects of sleep apnea or snoring. He also studied people who used a device to prevent apnea, known as a continuous positive airway pressure (CPAP) machine, which keeps airways open during sleep. Even though they snored or had sleep apnea, people who used the device developed MCI or Alzheimer’s at the same rate as those who didn’t have these sleep problems. CPAP machines are cumbersome and uncomfortable to use, and many people drop them after a few weeks. But, says Osorio, they may have more reason to stick with them now. “A lot of people don’t use them because they see no benefits,” he says, “but if they know it can improve their memory, they may definitely try to do better.”

Read next: 7 Signs You’re Not Getting Enough Sleep

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TIME Heart Disease

What Divorce Does to Women’s Heart Health

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When it comes to the fallout from a divorce, one spouse is harmed more by it’s biological and psychological effects on the heart

Dissolving a marriage is hard on everyone, but researchers say the psychological stress of a divorce can have serious physical effects on the heart, especially for women.

Women who divorced at least once were 24% more likely to experience a heart attack compared to women who remained married, and those divorcing two or more times saw their risk jump to 77%. In the study published in the journal Circulation: Cardiovascular Quality and Outcomes, Matthew Dupre of Duke University and his colleagues found that men weren’t at similar risk. Men only saw their heart attack chances go up if they divorced two or more times compared to men who didn’t split with their spouses. If men remarried, their heart risk did not go up, while for women who remarried, their chances of having a heart attack remained slightly higher, at 35%, than that of divorced women.

MORE: Divorce More Likely When Wife Falls Ill

These findings remained strong even after Dupre’s team adjusted for other potential contributors to heart attack, including age, social factors such as changes in occupation and job status and health insurance coverage, and physiological factors including body mass index, hypertension and diabetes. Previous studies have found links between divorce or widowhood and heart disease that were explained, at least in part, by changes in people’s access to health care and their ability to keep up healthy eating and exercise habits.

But these are the first results from tracking people over a longer period of time—18 years—to capture the cumulative effects of changes in marital status, says Dupre. “We looked at lifetime exposure to not only current marital status, but how many times someone has been divorced in the past. What we found was that repeated exposure to divorce put men and women, but particularly women, at higher risk of having a heart attack compared to those who were married.”

MORE: Study: Marriage is Good For The Heart

And it wasn’t simply changes in health insurance coverage or financial status resulting from the divorce that explained the higher heart risk. Even after Dupre’s group accounted for these, the relationship held. While he admits that the trial did not investigate exactly how divorce is seeding more heart attacks, other studies hint at a possible explanation. Dramatic life changes such as divorce, which signal an end to not only a significant relationship but potentially to stable financial and social circumstances as well, can lead to spikes in the stress hormone cortisol, which in turn can push blood pressure, cholesterol and blood sugar to unhealthy heights.

The long term scope of the study revealed the impact that social and life events can have on the physical functioning of the body. “The health consequences of social stresses are real,” says Dupre. For women, the 77% higher risk of heart attack connected to multiple divorces was on par with well-established factors such as hypertension (which boosts risk by 73%) and diabetes (which elevates heart problems by 81%).

MORE: Do Married People Really Live Longer?

That’s doesn’t mean, of course, that women should avoid getting divorced to save their hearts. “Another way to put it is to say that women who are stably married are at an increased advantage of preventing heart attacks than women who may have had to go through transitions where they weren’t,” says Dupre.

It also makes a good case for doctors including discussion about potential stressors, including lifestyle and social circumstances, in their health assessment of patients. Recognizing that divorce may be a life event that can contribute to higher heart attack risk, for example, they can monitor patients experiencing divorce more carefully, and be alert to the first signs of potential problems with cholesterol, blood pressure or blood sugar. “Understanding all of the factors that lead to a physiological response are equally important,” says Dupre. And potentially life saving.

TIME medicine

How Traumatic Life Events During Childhood Affect Diabetes

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Researchers say that traumatic life events can play a role in raising risk of type 1 diabetes

Type 2 diabetes tends to get more attention than type 1, mainly because the risk factors for type 2—obesity, for instance—are thought to be more in our control. Type 1 is believed to be primarily a genetic disease, triggered by an unfortunate DNA configuration that signals the body’s immune system to destroy insulin-producing beta cells.

Now, in a report published in the journal Diabetologia, Dr. Johnny Ludvigsson, a pediatrician from Linkoping University in Sweden, and his colleagues say that life events, including traumatic experiences such as the death of a family member or a serious accident, can triple the risk that young children have of developing the disease.

The researchers studied 10,495 families with children born between 1997 and 1999 and asked them to participate in at least one of four follow-up sessions when the children were between two and 14 years old. The parents filled out questionnaires about whether the children had experienced anything that might be considered a serious life event, including things like the death of a family member, a new sibling, divorce or a move. Parents were also asked about their own stress and whether they felt they had social support.

Once the scientists adjusted for factors that also contribute to type 1 diabetes, such as BMI, mother’s age and a history of diabetes in the family, children who experienced deaths and accidents in their early years showed a three-fold higher risk of developing diabetes than those who didn’t live through these events.

“People may be worried and have feelings of guilt that not only did their child get diabetes, but that in a way they contribute to it,” says Ludvigsson of the results. But parents should take some solace in the fact that after he adjusted for other factors that can contribute to type 1 diabetes, including BMI, mother’s age at child’s birth, and family history of diabetes, events such as divorce, new siblings and other changes in the family structure weren’t as strongly associated with an increased risk for the disease.

What may be happening is that some children may have a genetic predisposition to developing type 1 diabetes, but these genetic triggers aren’t “activated” unless they experience some extreme stress or trauma, such as the death of a loved one. Biologically, scientists believe that high stress situations may lead to a boost in the hormone cortisol, and that pushes the beta cells that produce insulin to work harder and release other potentially toxic factors as well. The added influx of insulin may be viewed by the immune system as abnormal and undesirable, which may prompt them to start attacking the beta cells and destroying them.

“This study does not say that you should never divorce,” says Ludvigsson. “But stress from life events can be one factor that influences the immune balance, just like many other factors do, like sleep, physical activity and so on.” Which highlights the need to address traumatic experiences and children’s reactions to them. Supporting families that go through difficult times, whether caused by marital conflicts or financial worries, could also be an important way to keep young children even healthier and to avoid certain chronic diseases. “If society could be a bit supportive, we could perhaps save some families and relationships, and that would be good for the children,” says Ludvigsson.

TIME medicine

Can Plastic Surgery Make You More Likeable? A Close Look at a New Study

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Sure, getting facial plastic surgery can make you look younger, but can it change your personality? Or at least what other people think of your personality?

Putting aside reconstructive surgery, facial plastic surgery is all about vanity. Which, let’s face it, means looking younger and more symmetrical. But erasing those signs of experience and maturity also changes the way other people see you. Like it or not, and socially acceptable or not, we make snap judgments about people based on purely superficial traits all the time. Furrowed brow? You might be interpreted as mean or anti-social. Heavy, hooded eyes? Clearly untrustworthy. While it seems ridiculous now, at one time in our evolutionary history, being able to make such determinations might have been life-saving: Who’s out to do us harm? Who is there to help?

MORE: From Kim’s Butt to Angelina’s Lips: The Plastic Surgery Procedures Women Want

In modern times, the sad truth is we still make snap judgments about certain facial features and the way we read some faces—as aggressive or unlikeable, say—tends to be connected with saggy skin, heavy chins and more crepe-like skin. That’s what plastic surgeon Dr. Michael Reilly from Georgetown University and his colleagues found in a report published in JAMA Facial Plastic Surgery.

In his study, he asked people to rate either before or after photos of women who had had cosmetic procedures. Not only did he ask them to evaluate how attractive and how feminine she was, he also had people make guesses about her personality based on the photos. Why the personality traits? Previous studies have shown that physical features have a strong correlation to certain personality types, and Reilly says he wanted to understand exactly how the changes he made as a plastic surgeon were affecting his patients. “If I’m embarking on this career, and if I’m doing this type of surgery, I want to know what I’m doing to patients,” he says. Laudable, certainly, but what are the raters’ responses really telling us? The raters never saw the before and after pictures of the same person, which Reilly says he did in order to reduce any potential bias.

Reilly found that people consistently rated the post-op photos as higher on things like social skills, likeability, femininity and overall attractiveness. Not a surprise, given that cosmetic procedures are supposed to improve attractiveness. But likeability? Social skills? Not to mention trustworthiness and risk-seeking?

MORE: Here Are the Most Popular Plastic Surgery Procedures In Three Charts

For one, asking people to rate faces on these characteristics is a bit artificial to begin with. The personality traits people were asked to assess have biased terms—like “aggressiveness,” says Dr. Sam Lam, a facial plastic surgeon practicing in Dallas, who wrote an editorial accompanying the study. Raters might be saying that faces have certain traits only because they’re forced to make a choice when they might not if they weren’t in a study setting.

The results also reinforce the fact that — surprise!— our society has a bias against aging. Since the post-op, and presumably younger-looking, images of the same women seemed to score higher on things like social skills and likeability than their pre-op pictures, that strongly suggests that aging-related features are associated with less-than-desirable personality traits like anti-social behavior. “Aging reverses positive dynamic expressions like smiling,” says Reilly, noting that when we smile, we bring our cheeks up and tighten certain facial muscles. “When we age, our faces look like the opposite of a smile.”

MORE: Plastic Surgery Doesn’t Work — but Neither Does Our Standard of Beauty

Yet couldn’t aging also be seen in exactly the opposite light, as a factor that makes someone more adept and experienced at social interactions and therefore more likeable than a younger person who is more awkward and uncomfortable navigating among strangers?

A previous study from 2013 of before and after plastic surgery ratings didn’t find the same improvement in attractiveness that the current one did. In that study, people looking at photos of patients pre- and post-op didn’t think the procedures made patients any more attractive, and only seemed to make them look about three years younger.

Which only goes to show that we still have a long way to go before we can figure out exactly what we’re doing to ourselves when we go under the knife for cosmetic procedures. We’re changing our outward appearance, yes, but how that affects our inner selves and how others perceive us isn’t — and likely won’t ever — be entirely clear.

TIME ebola

A New Ebola Vaccine Shows Promise

With nearly a dozen Ebola vaccines now in various stages of development, researchers of one report promising results against the recent strain

A vaccine designed from a crippled virus with Ebola genes stitched in—the first tested against the strain that caused the outbreak in West Africa that has killed 10,000 and infected thousands more—protected every monkey tested from being infected with Ebola.

Reporting in the journal Nature, Thomas Geisbert, a virologist from the University of Texas Medical Branch, and his colleagues describe a vaccine made from a virus that commonly infects cows—called vesicular stomatitis virus (VSV)—that’s had some of its genetic material replaced with genes for surface proteins from the Ebola virus. None of the eight monkeys inoculated with the shot showed any signs of severe Ebola infection after being exposed to the virus 28 days later, while both of the control animals died of the disease seven and eight days after infection.

MORE: Ebola Vaccine Is Safe and Effective, According to First Study

The vaccine is the second generation of one that Geisbert and Heinz Feldmann, from the National Institute of Allergy and Infectious Diseases, co-developed in the 2000s. But because the vaccine relies on a live, albeit hampered virus, it raised concerns about safety that killed-virus vaccines, like polio and hepatitis A, don’t have. Neither the VSV nor Ebola virus are capable of replicating, since the VSV has part of its genome cut out and replaced with Ebola material, and the Ebola virus only has its outer surface genes and none of its dividing machinery. But a growing virus, even a slowly growing one, can cause problems. That’s what researchers saw in an early human trial of the first generation VSV Ebola vaccine, which was tested among 40 healthy volunteers in the Washington DC area. Some developed arthritis-like conditions, which added to existing concerns about the vaccine’s safety profile.

MORE: The Ebola Fighters

“Clearly there was a lot of room for improvement. It’s a balancing act,” says Geisbert. “What makes it such a good vaccine is that it grows. But we are trying to find the balance between efficacy and safety.”

MORE: The First Ever Large-Scale Ebola Vaccine Trial Begins in Liberia

He may have hit upon that parity with the latest version of the shot. By changing where in the VSV genome he inserted the Ebola genes, he found a vector that seems to deliver the same immune response against the Ebola virus, yet at lower cost to the person being vaccinated. The VSV loaded with Ebola grew at a five to 10 times slower rate than it did in the first vaccine, and animals inoculated with the newer vaccine showed 10 to 50-fold lower levels of both VSV and Ebola in their blood compared to animals given the first generation shot.

The slower growing VSV, says Geisbert, “in a well ordered universe is associated with less possibility of an adverse event” from the vaccine.

That won’t be known for sure until the vaccine is tested in the first healthy human volunteers, which may happen as soon as this summer.

TIME Diet/Nutrition

Which Weight Loss Diet Works Best? A New Study Ranks the Evidence

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With so many ways to lose weight, you’d think it would be easy to tell which diet program works best — Weight Watchers or Jenny Craig, Nutri System or Slim Fast. But it might surprise you to learn that there isn’t a lot of good evidence on how effective various diets are, and here’s why

With the American Medical Association now urging doctors to treat obesity as a medical condition, physicians should be screening and treating overweight and obesity just as they would any other chronic disorder. But when it comes to figuring out which methods are proven to work best, physicians may find themselves at a loss. Some studies have found that commercial weight-loss programs work about the same when it comes to the amount of weight they can help consumers lose, while others found that low-carb diets beat out low-fat plans.

To make sense of the noise, Kimberly Gudzune, an assistant professor of medicine at Johns Hopkins University, and her colleagues searched the scientific literature for studies on 11 commercial weight-loss programs. In their results, published Monday in the Annals of Internal Medicine, they assessed which ones have the best data to support them. But they also found there weren’t that many studies actually tracking how much weight people on the programs lose.

Gudzune decided to focus on commercial programs like Weight Watchers and NutriSystem, among others. And of 4,212 studies that involved these diets, only 45 were done under the gold scientific standard of randomly assigning people to a weight-loss program or not, and then tracking their weight changes over time. “The majority [of programs] still have no rigorous trials done,” says Gudzune.

According to her analysis, only two programs, Weight Watchers and Jenny Craig, helped dieters to lose weight and keep it off for at least a year. Those on Weight Watchers shed nearly 3% more of their starting weight after 12 months than those not dieting, and Jenny Craig users lost nearly 5%. Other programs, including Atkins, the Biggest Loser Club and eDiets, also helped people drop pounds, but since the studies only lasted three to six months, it’s impossible to know if that weight loss lasted.

The modest weight loss “may be disappointing to many consumers,” says Gudzune, but she notes that weight-management guidelines suggest that a 3% to 5% sustained weight loss is an important first step toward a healthy weight. “Even that small amount of weight loss can help to lower blood sugar, improve cholesterol profiles, help to lower blood pressure and ultimately prevent things like diabetes,” she says.

“Would 6% or 8% or 10% of body weight lost be better? Yes, but it’s not like the interaction is totally linear,” says Gary Foster, chief scientific officer of Weight Watchers International. Over time, weight-loss rates may change, and other studies show they typically slow after the initial blush of success.

MORE Calorie vs. Calorie: Study Evaluates Three Diets for Staying Slim

Modest weight loss can also seed good eating habits that can keep weight loss going, or maintain weight at a healthy level. “Modest weight loss on average can translate to a big public-health impact” on the obesity epidemic, says Dr. Christina Wee, associate professor of medicine at Harvard Medical School and director of the obesity-and-health-behaviors research program at Beth Israel Deaconess Medical Center. Fewer overweight and obese individuals mean fewer cases of diabetes, heart disease, hypertension, joint disorders and more. So for doctors faced with advising their patients on how to best manage their weight, these are the first bits of evidence that some commercial programs — Weight Watchers and Jenny Craig — might be better than others in helping patients to slim down and stay that way.

Still, a larger robust bank of evidence-based studies is needed. Typically, studies follow dieters for about three months, during which most people are likely to lose the most weight because they are more motivated and simply because they in a study and feel obligated to follow the diet. That’s another problem with the studies on diet programs, says Wee. “When trying to do a scientific study, researchers don’t want too many things going on at the same time, so they end up with a design for the study that doesn’t reflect the real world,” she says. “So the result is the result from an artificial setting.”

MORE: Diet Bake-Off: Jenny Craig Wins, Says Consumer Reports

Another factor that makes studying diets tricky is the fact that participants are assigned a diet. In real life, people tend to try a weight-loss program of their own choosing. When they find that it doesn’t fit with their lifestyle or personality, they try another. They may be more successful with their second or third choice, but in a study, they would fall into the failure category if they didn’t lose the target amount of weight on the first program.

“Now that obesity is coming under the medical umbrella, it’s really going to put more pressure on whether commercial programs or medical clinics have really good evidence to show their programs are effective,” says Gudzune. “For so long obesity was just in a no-man’s land, which I think did it a disservice because it didn’t push the industry to have better scientific evidence on what works and what doesn’t work.”

And it’s not just physicians seeking this proof. With the Affordable Care Act now covering obesity screening and counseling, and providing incentives to states to reimburse for comprehensive obesity treatments, it’s critical for insurers and policymakers who decide which weight-loss programs are worth paying for and which ones to deny.

Read next: Popular Diets Are Pretty Much the Same for Weight Loss, Study Finds

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