A study published in The New England Journal of Medicine found that nearly 604 million adults and 108 million children are obese. Ruth Fremson/The New York Times
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About what percent of the world's population is now obese?

5 percent
10 percent
20 percent
40 percent
Anderson Cooper, age 37, in 2005. Michael Nagle for The New York Times
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Hair can turn gray prematurely as a result of:

Smoking
Genetics
Heart disease
All of the above
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College students at a school cafeteria were most likely to pick up a sweet potato dish labeled as:

Sweet potatoes
Wholesome sweet potato superfood
Cholesterol-free sweet potatoes
Zesty ginger-turmeric sweet potatoes
Getty Images
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To prepare for an athletic competition in hot weather, this method might produce the best results, a new study suggests:

Wearing frozen undergarments during a race
Drinking slushies during the race
Taking long, hot baths in the days preceding the event
All were equally effective
Paul Rogers
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Lacking a network of friends has been tied to an increased risk of:

Heart attacks
Cancer
Autoimmune disorders
All of the above
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A study of 420 people living near Athens International Airport found that nighttime exposure to airplane noise increased the risk of:

High blood pressure
Stroke
Diabetes
All of the above
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Doctors may be prescribing too much of these drugs to women who have had a cesarean delivery, a new study suggests:

Oxytocin
Statins
Opioids
Sedatives
Guyco
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This organ, the largest internal organ in the body, grows and shrinks in size by up to 40 percent over the course of a day and may influence our cravings for sweets:

Stomach
Liver
Pancreas
Kidneys
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