When it comes to your health, you can be too fat or too skinny.

Everyone knows that obesity is linked to a host of ailments and a shortened life expectancy, but so, too, is being significantly underweight. Canadian researchers reviewed 51 studies on the links between body mass index and death from any cause.

They found that adults who were underweight — a BMI under 18.5 — have a 1.8 times higher risk of dying than those with a "normal" BMI of 18.5 to 24.9. Factors such as smoking, alcohol use and lung disease were considered, and adults with chronic or terminal illnesses were excluded.

"BMI reflects not only body fat, but also muscle mass," said Dr. Joel Ray, a study author from St. Michael's Hospital in Toronto. "If we want to continue to use BMI in health care and public health initiatives, we must realize that a robust and healthy individual is someone who has a reasonable amount of body fat and also sufficient bone and muscle. If our focus is more on the ills of excess body fat, then we need to replace BMI with a proper measure, like waist circumference."

BODY OF KNOWLEDGE

You're born with more than 300 bones, but as you age, some fuse together (think about your skull, for example), and by the time you're an adult, you have 206.

NUMBER CRUNCHER

One maple-frosted doughnut from Dunkin' Donuts (70 grams) contains 270 calories, 135 from fat. It has 15 grams of total fat, or 23 percent of the recommended total fat intake for a 2,000-calorie daily diet.

It contains 0 milligrams of cholesterol; 340 milligrams of sodium (14 percent); 32 grams of total carbohydrates (11 percent); 1gram of dietary fiber (4 percent); 14 grams of sugar; and 3 grams of protein.

COUNTS

8.6 — Number, in millions, of people worldwide who contracted tuberculosis in 2012

1.3 — Number, in millions, who died from tuberculosis in 2012

Source: World Health Organization

STORIES FOR THE WAITING ROOM

In England, researchers announced the first documented cases of people catching tuberculosis from their cats, a phenomenon described as exceedingly rare. All four cases were related to a rare cluster of sick cats in southern England, each infected by bovine tuberculosis, most likely from eating rodents who had come into contact with TB-carrying cows or badgers, who also host the bacteria.

Health authorities said the likelihood of something similar occurring in the United States is vanishingly small. Bovine tuberculosis infections comprise about 1 percent of TB cases in the U.S., and typically originate from consuming unpasteurized milk, which is illegal to sell.

PHOBIA OF THE WEEK

Merinthophobia — fear of being tied up

NEVER SAY DIET

The Major League Eating speed-eating record for vanilla ice cream is 1.81 gallons in 6 minutes, held by Joey Chestnut. There is no record of how long the resulting headache lasted.

BEST MEDICINE

A physician notices Bob, an inveterate hypochondriac, sitting in his waiting room.

"Not again, Bob," says the doctor. "It's only Wednesday. You were here Monday."

Bob nods: "Couldn't come yesterday. I was sick."

LAST WORDS

"Don't worry, it's not loaded." — American musician Terry Kath (1946-1978), who died from an unintentional, self-inflicted gunshot wound while playing Russian roulette

To find out more about Scott LaFee and read features by other Creators Syndicate writers and cartoonists, visit the Creators Syndicate website at www.creators.com.