HEALTH UPDATE: FIVE STUDIES YOU MAY HAVE MISSED

And this time they deal with hot topics like aging, obesity, and the impact of (gasp!) pornography.  Read on:

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Here's a roundup of five medical studies published this week that can give you new insights into your health, mind and body. Remember, correlation is not causation – so if a study finds a connection between two things, it doesn't mean that one causes the other.

The entire world is getting fat
Journal: The Lancet
In what is the most comprehensive look at global obesity in decades, scientists said they can’t find a single positive note in the fight against the epidemic.
In every single country they studied - there were 188 of them - the obesity rates stayed the same or got worse.
Nearly 30%, or almost one out of every third person on this planet, is overweight or obese, according to the study. In 1980 there were 857 million people considered overweight or obese. In 2013, that number was 2.1 billion.
Obesity is more of a common problem in the developed world, but it has become a growing problem in poorer countries.
The country with the most obese people is the United States. About a third of American adults are overweight, which accounts for 13% of all the heavy people worldwide. The United States is only a little over 4% of the world's population, so that's a startling statistic.
Women saw the bigger gains. Between 1980 and 2013, the rate of women who are obese increased from 29.8% to 38%. For men it increased from 28.8% of the population to 36.9% of the population.
Read more from PLOS Blogs

Men who watch a lot porn may have smaller brains
Journal: JAMA Psychiatry
Men who watch a lot of porn are a little lighter when it comes to their gray matter, according to a  study out of the Max Planck Institute for Human Development in Berlin.
Scientists made brain scans of a small group of 64 healthy men from 21 to 45 as they looked at pornographic images. Researchers also assessed how often the men typically looked at porn.
The study may be the first to establish a link between the amount of pornography consumption and brain size. The study does not determine whether men who watch a lot of porn have smaller brains to begin with or whether the volume of their brains has shrunk over time.
The study did show that the region of the brain that activates when someone experiences sexual stimuli is less active in those men who typically watch a lot of porn.
Read more from TIME.com
Want to look younger? Avoid the sun, smoking and high-calorie diets
Journal: Cell Press
Forget special creams and surgeries to look younger - what you really need is to avoid cigarettes and sunshine, according to scientists at the University of North Carolina.
If you avoid “gerontogens" - that’s the fancy word for stuff in the environment that may make you age - you may look younger and may even live longer.
Other “gerontogens” include the chemicals used in chemotherapy. A low-calorie diet may also slow aging, as may a low-stress environment, according to the study.
We still don’t know why some people age faster than others. But the researchers hope their study will someday lead to a blood test that would allow doctors to look at someone’s DNA for biomarkers of aging. Those biochemical signatures would help determine how fast a person is aging and why, and perhaps slow or stop the process. That’s a long way off though. This study is still in the mouse model phase.
Read more: Cell Press release
Teen sunbathers beware: 5 bad sunburns increase risk for deadly cancer
Journal: Cancer Epidemiology, Biomarkers & Prevention
People who say they had more than five or more blistering sunburns before they turned 20 have an 80% increased risk of melanoma, the most deadly form of skin cancer.
A study examined the health of 108,916 registered nurses for 20 years. Of those nurses, the ones who had five or more bad sunburns, the kind with blisters, when they were ages 15 to 20, had a 68% increased risk for basal cell carcinoma and squamous cell carcinoma and an 80% increased risk for melanoma.
People who had a similar number of bad sunburns when they were older faced no similar increased risk for melanoma, but they did have a greater chance of developing basal cell or squamous cell carcinoma.
Scientists caution people who have a propensity to develop moles or who sunburn easily should take particular care in the sun, especially early in life.
Read more: American Association of Cancer Research
Laser treatment helps tooth regeneration in mice
​Journal: Science Translational Medicine
Lasers sound a lot more fun than root canals. Scientists demonstrated in a new study that it's possible to regenerate dentin, the hard bone-like tissue in teeth, using light.
The technique makes use of stem cells already found in teeth. Researchers did not have to transplant these cells that have tremendous potential in regenerative medicine.
By shining infrared light on damaged teeth in mice, scientists activated molecules called reactive oxygen species. These molecules bind to stem cells, making the stem cells turn into dentin-forming cells that help regenerate the tooth structure, said David Mooney, senior author of the study and researcher at Harvard University.
Scientists demonstrated this in rodents, but not humans, however. Also it's a somewhat lengthy process, which would take weeks to months to work.
If it were successful in humans, though, the technique "potentially could replace the root canal," Mooney said.
Read more from Harvard