Four of five older children and teens around the world don’t get the recommended amount of physical activity, a new study says.

Researchers analysed data gathered between 2001 and 2016 from 1.6 million students, aged 11 to 17, in 146 countries. They found that 81% of them did not meet World Health Organization recommendations for an hour of moderate-to-vigorous physical activity every day.

‘Urgent policy action’

Girls were less active than boys in all but four countries: Tonga, Samoa, Afghanistan and Zambia. In nearly one-third of countries (29%), girls were more than 10 percentage points less likely to meet the WHO recommendations. The biggest gaps were in the United States and Ireland, at more than 15 percentage points.

In 73% of the countries, the gender gap increased between 2001 and 2016. In 2016, 90% or more of girls in 27 countries did not have sufficient levels of activity. Among boys, this occurred in only two countries.

Boys in the Philippines and girls in South Korea were the most inactive, while Bangladesh had the lowest rates of physical inactivity for both genders, according to the WHO-led study. It was published in The Lancet Child & Adolescent Health journal.

“Urgent policy action to increase physical activity is needed now, particularly to promote and retain girls’ participation in physical activity,” study author Regina Guthold said in a journal news release. She is a technical officer from Chronic Disease Risk Factor Surveillance at WHO in Geneva.

Physical inactivity can harm children’s health, the researchers noted.

Boosting physical activity

The benefits of physical activity during adolescence include improved heart, lung and muscular fitness, better bone health, and weight control. There is also growing evidence that physical activity benefits brain health and social skills.

Many of these benefits continue into adulthood, research suggests.

“The study highlights that young people have the right to play and should be provided with the opportunities to realise their right to physical and mental health and well-being,” said study co-author Fiona Bull. She is director of the Centre for Built Environment and Health at the University of Western Australia and president of the International Society for Physical Activity and Health.

“Policymakers and stakeholders should be encouraged to act now for the health of this and future young generations,” Bull said.

The researchers called for: expansion of policies and programmes known to boost adolescents’ physical activity; more action from sectors such as education, urban planning and road safety to provide more opportunities for young people to be active; and political and other leaders to promote the importance of physical activity for all people, including adolescents.

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Designing the best molecular building blocks for battery components is like trying to create a recipe for a new kind of cake, when you have billions of potential ingredients. The challenge involves determining which ingredients work best together — or, more simply, produce an edible (or, in the case of batteries, a safe) product. But even with state-of-the-art supercomputers, scientists cannot precisely model the chemical characteristics of every molecule that could prove to be the basis of a next-generation battery material.

Regular fasting is associated with lower rates of heart failure and a longer lifespan, according to two new studies.

Researchers sought to shed new light on the centuries-old debate about how fasting affects health. Recent studies have shown it contributes to reductions in blood pressure, “bad” LDL cholesterol and insulin resistance, a condition that can raise blood sugar. A 2017 study showed alternate-day fasting was as effective as daily calorie restriction for losing weight and keeping the pounds off.

A profound effect

The new studies focused on data from patients evaluated for heart disease in Utah and other Rocky Mountain states. The research included hundreds of members of The Church of Jesus Christ of Latter-day Saints, also known as Mormons, who typically fast one Sunday each month, for up to 24 hours.

In the first study, researchers zeroed in on how fasting impacts life span. About 2 000 people who had undergone a cardiac catheterisation procedure were followed for an average of 4.4 years, including 389 “routine fasters” who had been fasting regularly for at least five years.

After adjusting for various factors, researchers discovered the routine fasters had a 45% lower mortality rate than the non-fasters during the follow-up period.

“It’s very interesting … it’s a more profound effect than we anticipated,” said researcher Dr Benjamin Horne, who recently presented the preliminary findings at the American Heart Association’s Scientific Sessions.

Horne also was involved in the second fasting study, which used the same patient data to see how routine fasting affects heart failure and heart attacks. After adjusting for various factors, there was no significant difference in heart attacks, but routine fasters had a 71% lower rate of developing heart failure than non-fasters.

A very different lifestyle

“That’s a huge difference, and frankly, it was a little unexpected,” said Horne, director of cardiovascular and genetic epidemiology at Intermountain Medical Center in Salt Lake City, Utah.

Krista Varady, an associate professor of nutrition at the University of Illinois at Chicago, called it “an important study that hasn’t been done before. There’s a lot of short-term clinical trials for intermittent fasting, but we definitely don’t have any long-term data in humans looking at whether it can prevent things like heart failure.”

Varady, who was not involved in the research, said the study was limited by the fact that most of the fasters were Latter-day Saints.

“They lead a very different lifestyle compared to the average American,” she said. “For instance, they don’t smoke, don’t drink alcohol and are slightly more physically active. It just makes sense they’re going to live longer and have a lower chance of heart disease.”

Even though researchers adjusted for some of those factors, she said, “It is very difficult to tease apart the effects of fasting versus an otherwise healthy lifestyle in this population, despite the use of statistical corrections.”

The hours build up

A number of hot diet trends encourage people to restrict their eating to a window of eight to 12 hours and fasting the remaining 12 to 16 hours. But participants in the two new studies fasted even more hours each day, over the course of an average of 42.2 years, Horne said.

“We think that long-term fasting of about one day, once a month, over a period of decades is making the body activate those beneficial mechanisms for a few hours each day between dinner and breakfast when it usually wouldn’t. … Those hours build up over long periods of time and provide the benefits,” he said.

The research was limited by being an observational study that doesn’t prove cause and effect, Horne said. He’d like to see future studies that explore why fasting seems to protect against heart failure, and he also called for a large study on the psychological benefits of fasting.

“Some people who’ve started fasting say they unexpectedly feel they have more self-control over their appetite,” he said. “Potentially, there’s a direct result between fasting and the strengthening of the mind so people are able to eat a better diet.”

Varady called for future studies that follow people who restrict eating in a variety of ways – such time-restrictive fasters and alternate-day fasters. “This is a nice first step, but we need to do long-term research on different people doing different types of fasting.”

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Jeremy Corbyn says his party has a 451-page dossier of evidence – but the Tories say he is lying.

Karen Bonham struggled to find the information she needed ahead of radiotherapy – so she created an app.

Patients could have waited more than 19 weeks – 50% longer than the target time – in some areas.

Sarah Hyland just gave her fans a lesson in self-love. In an emotional Instagram post on the changes her body has gone through as a result of living with kidney dysplasia, the actress, 29, opened up about her struggle with self-acceptance. 

RELATED: Modern Family's Sarah Hyland Is Frustrated with 'Doctors Not Listening' to Her Health Struggles

“To my fellow #invisibleillness warriors. It’s ok to be insecure about your body,” she wrote in the caption to her post from Sunday, which featured a photo of her in a sports bra and her abs on full display.

“Just remember to check in with yourself at least once a day and say thank you. Our bodies have endured unfathomable feats that our minds barely have time to comprehend what has actually happened. With inflammation, excess water gain, and medications, my skin has a hard time bouncing back.”

Hyland added that she first hated the sports bra photo, but ultimately she decided to change her attitude and celebrate her body as it is by sharing it.

“Love yourself and be patient,” she wrote. “We are all stronger than we think we are.”

Her fans were in full support of her message. After just a day, the star received more than 4,700 comments, with people praising her for her honest response. 

RELATED: Sarah Hyland Likes Working Out Naked in Front of Mirror For Motivation

Hyland's invisible illness, kidney dysplasia, is a congenital condition that causes painful cysts to form in her kidneys. In 2012, she underwent a kidney transplant, yet four years later, her body rejected the kidney that had been donated by her father, which had to be removed.

Four months later, she had a second transplant using her younger brother’s kidney, which Hyland felt conflicted about.  

“I was very depressed,” she said. “When a family member gives you a second chance at life, and it fails, it almost feels like it’s your fault. It’s not. But it does. For a long time, I was contemplating suicide, because I didn’t want to fail my little brother like I failed my dad.”

Since then, Hyland has had the support of her family, fans and fiancé, Wells Adams, to help her through her recovery from the transplant and her struggles with the emotional side of dealing with a serious medical condition. With her latest post, she's acknowledging these difficulties and encouraging others to feel strong and empowered.

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An Atlanta couple forced to seek medical treatment while on a cruise vacation now say they’re being held “hostage” by a hospital in Mexico over an unpaid $14,000 medical bill.

Stephen Johnson, 31, and fiancée Tori Austin were two days into their trip on a Carnival Dream cruise ship when Johnson fell ill and was diagnosed on board with pancreatitis and diabetes, CBS affiliate WGCL reported.

At the behest of Carnival, Johnson sought treatment and was hospitalized in the Mexican town of Progreso, where he spent three days in intensive care, Good Morning America reported.

RELATED: This Couple Was Paying so Much for Their Son's Disability, a Doctor Suggested Getting a Divorce

Once he was on the mend, however, he was hit with a $14,000 bill that the couple is unable to pay, as they do not have health or travelers’ insurance.

“The plan is to pay the bill, it’s not to skip out on the bill,” Austin told GMA. “They saved his life. His life is more than $14,000.”

Austin said she offered $7,000 upfront and asked if they could work out a payment plan for when they were back in the U.S., but that her request was denied, and she and Johnson were barred from leaving the hospital.

RELATED: Couple Found Dead from Murder-Suicide After Man Said He Couldn't Afford Health Care for His Wife

“We tried to leave Tuesday, but we were physically assaulted by the administrative staff,” she alleged. “They physically were pushing on him.”

Austin also claimed that hospital staffers locked the windows to further prevent them leaving, and threatened to call the police should they make a break for it.

“It’s been a nightmare. We just want to come home,” she told WGCL. “$14,000 in a matter of hours, I don’t know who has that type of money.”

RELATED: This Woman Wants to Make It Less Awkward for Sick People to Ask for What They Need

Added Johnson, “[It’s] hell. I very much so am a hostage. Don’t get sick and have to come to this hospital, that’s one thing I can tell you. They won’t let you leave.”

A U.S. Department of State official confirmed to PEOPLE on Friday that a U.S. citizen was being treated at a Progreso hospital, and that a consular officer visited the citizen in the hospital on Thursday.

The official said the department was monitoring the situation closely.

RELATED: This Dad Says His Baby Was Charged $3,500 For His Own Delivery—How Common is That?

Austin, meanwhile, shared an emotional video to Facebook on Wednesday, telling her followers she and Johnson were “coming home” and that someone had offered to pay their entire bill.

“Thank you whoever gave the money,” Johnson could be heard yelling in the background of the video.

Austin later wrote on Facebook Friday morning that she and Johnson were still “waiting” in Mexico.

Carnival confirmed to PEOPLE in a statement that a guest on the Carnival Dream had suffered a medical emergency and “was required to seek medical treatment in Progreso.”

“We are not in a position to comment on the personal matters related to his health or the financial arrangements regarding his treatment, but our CareTeam is providing support,” the statement read.

Austin, however, praised the company in a Facebook post, and wrote that their support had been “great” throughout the ordeal, though she did not go into specifics.

The hospital did not immediately respond to PEOPLE’s request for comment.

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Jenna Dewan is reminding everyone to take a break and schedule some self-care time. The actress and dancer, who is currently pregnant with her second child, shared a makeup-free selfie with an important message about getting a chance to rest, recover, and feel more gratitude. 

“A day off today and I haven’t moved from bed not kidding." she wrote in her post on Saturday. "Lots of time to rest, recuperate and reflect on how grateful i am for love, joy and especially my health. Remembering what’s important and to slow down every now and then "

RELATED: Jenna Dewan Twerks Through Her 'Late-Night' Fitness Routine Following Split from Channing Tatum

Unsurprisingly, fans were in awe of her natural beauty and had plenty to say about the star's photo. 

"Rest. Take care of yourself and your baby ," one fan wrote, with another adding, "Some days our body needs that "

RELATED: Ellen DeGeneres’s On-Air Mistake Prompted Jenna Dewan to Talk About Ex Channing Tatum

This wasn't the first time that Dewan has posted images of her face au natural. In 2017, she shared another makeup-free selfie to Instagram, noting that she struggles with melasma—a skin condition causing dark spots or patches to appear on the face. Melasma can be triggered by too much time in the sun or hormonal changes brought on by birth control pills or pregnancy, for example. 

Needless to say, she looks incredible with or without makeup and melasma—and her message about scoring plenty of R&R is something everyone needs to remember as the holiday season hits.

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New insight on the extinction history of a flightless seabird that vanished from the shores of the North Atlantic during the 19th century has been published today in eLife.