(CBS NEWS) -- Health trends come and go — some helpful, some not so helpful, and some downright dangerous. CBS News asked medical experts about some of the popular trends they recommend ditching in 2017.

Trend: Cooking with coconut oil

“People seem to be eating it and drinking it with everything — adding it to coffee, cooking their vegetables with it — and it’s giving them large quantities of fat. I wish this trend would go away,” said Dr. Andrew Freeman, a cardiologist and director of Cardiovascular Prevention and Wellness at National Jewish Health in Denver, Colorado.

Trend: Smartphone apps to diagnose melanoma

Don’t use an app to diagnose skin cancer, said Dr. Abigail Waldman, a dermatologist at Brigham and Women’s Hospital in Boston and an instructor at Harvard Medical School.

Trend: Guzzling water all day long

Carrying a water bottle around and chugging H20 all day long won’t bolster health, said Dr. Stanley Goldfarb, a professor at Perelman School of Medicine at the University of Pennsylvania.

Trend: Bone broth for nutrition

Bone broth has become popular with nutrition-conscious consumers but it’s not the magical brew it’s touted to be, said Linda Antinoro, a registered dietitian at Brigham and Women’s Hospital.

Trend: Bottled fruit smoothies

Bottled fruit smoothies are packed with sugar, said Antinoro.

Eat fresh fruit or make your own, versus the sugar-laden bottled ones. Not to bash any brands, but a 15-ounce bottle can have 40 to 50 grams of sugar. That is about 10 to 12 teaspoons of sugar,” Antinoro said.

Trend: High-tech medical tests

With medical technology booming, it’s tempting for some people to undergo tests “just to be sure.” But it may be risky.

Dr. Eliot Nierman, a general internist and associate professor of clinical medicine at the University of Pennsylvania, said people can overdo it on medical tests these days. He said it’s time to scale back and question the necessity of undergoing tests that aren’t recommended, based on the evidence, before they’re performed.

Trend: “I’m not a person who needs a lot of sleep”

“There are some people who claim they don’t need sleep,” said Penn’s Nierman, but it’s not true for most.

Most people need seven hours a night, and some even more, he said.

Trend: Setting a weight-loss pound goal

“Setting a goal of losing like 30 or 50 pounds isn’t recommended,” said Elisabetta Politi, nutrition director of the Duke Diet and Fitness Center at Duke University.

It sets people up for frustration over time. Weight loss is a long, steady process, she said, and it may help to approach it with smaller, more reachable goals.

Trend: Hot yoga and hot fitness classes

More than 36 million U.S. adults practice yoga, according to a 2016 Yoga Alliance report, and while its many benefits are well known — it improves strength and flexibility, and can help lower stress, among other health perks — there’s one type of yoga that some experts recommend crossing off your list in 2017.

Trend: No snacking after dinner

Snacking in the evening a couple of hours after dinner isn’t necessarily the big diet-buster it’s cracked up to be. It can actually be good for you if it’s healthy and light, said Dr. Michelle Terry, a clinical professor at the University of Washington and an attending physician at Seattle Children’s Hospital.

MORE: Read the full version of this story at CBSNEWS.com, tap here