Blog Posts by YouBeauty.com

ThinkstockWhen it comes to sunscreen, how much you use is just as important as when and what you apply. A swipe here and a dot there just won't cut it. "Most people only apply a percentage of the amount necessary, making an SPF 30 closer to an SPF 15," says New York dermatologist Dr. David Bank.

One ounce of sunscreen-the equivalent of a full shot glass-slathered from head to toe is what you should aim for.

So we tested the full one-ounce dose and calculated just how much needs to be applied (to each body part) to protect skin and beat the burn. Full disclosure: It was quite greasy. Allot considerable rubbing-in time.

MORE: NEW FDA Sunscreen Rules

Face

A penny-sized dollop of broad-spectrum sunscreen is what is needed to shield your face from damage. Don't forget the hairline, hair part, the tops of your ears and even your eyelids-some of the most delicate and oft-forgotten areas, according to Bank.

Neck and Décolletage

A dose about the size of two almonds fully

U.S. Olympic Gymnast McKayla Maroney (Getty)A swatch of fabric sewn over an elastic band has turned into the most maligned hair accessory of, oh say, ever. That's right, we're talking about the scrunchie-a much adored, 80s hair accessory that slowly faded from grace, only to become an object of derision when worn in public or for any reason other than holding back one's hair while washing your face. Perhaps the culminating blow came when Carrie Bradshaw herself famously shot them down in "Sex and the City's" sixth season:

Carrie: You have your leading lady running all over town wearing a scrunchie?

Berger: What's wrong with that?

Carrie: Nothing. Unless you're writing about women on the island of Manhattan, in which case... where do I begin?

Here's the thing though-scrunchies are actually darn good for your hair. They don't cause breakage or tug at fragile strands like thin elastic bands do and they hold hair in place like nobody's business. "Scrunchies are much better for your hair than typical ponytail

The ScienceShutterstockBehind Grays

It's long been believed that we go gray when the cells in the hair follicle (called melanocytes) stop injecting the strands with melanin. For most people those first errant strands start popping up sometime in the mid-30s to early 40s, but for others it occurs even earlier than that. The result: an unpigmented hair that, despite its gray appearance, is actually white.

MORE: The Best Hair Color for Your Skintone

"Each hair follicle stops producing melanin at different times so the combination of white hairs lying against other colored strands, makes them appear gray," says Perry Romanowski, a cosmetic chemist in Chicago.

But a breakthrough three years ago at the University of Bradford in Great Britain found that was only half of the gray hair puzzle. They discovered that youthful hair cells produce hydrogen peroxide that's easily converted into hydrogen and oxygen. But as we age, even that system starts slowing down leaving hair to

Eight yoga claims, examined.Yoga has been touted as a cure-all, promising a slimmer, leaner body, improved cardiovascular health and a hotter sex life. But are popular claims about yoga's endless benefits stretching the truth?

MORE: A Guide to Yoga for Beginners

In the new book "The Science of Yoga: The Risks and the Rewards," William J. Broad, a senior writer for the New York Times and himself a devoted yoga lover, looked at the available science to help establish precisely what yoga can and can't do. "There's a mystique that rolls out of India and all things Eastern, which can get mixed up and produce a powerful image that can be dangerous to the extent that it can be misleading," Broad explains. "The science can be a wonderful tonic and helps clarify what's real and what isn't, what's good and what's bad."

Broad says the ancient form of exercise can do far more good for you than bad, but it's still important to separate fact from fiction. Here are eight common beliefs about yoga-and the

Ever gone demi-permanent?When you're looking to cover up grays, there are a few ways to do it.

You can use a semi-permanent hair color if you want the color to last for just a few shampoos (great, for example, if you want quick coverage for a party). If you're looking to make a long-term commitment, you'll want to seek out permanent color. Rather than washing out, this type of dye needs to grow out of your hair-leaving dreaded gray roots in its wake.

QUIZ: How Healthy is Your Hair?

But somewhere in the middle lies the hair color sweet spot that many women crave. It's called demi-permanent hair color.

"This type of product will stay in the hair for 28 shampoos," explains Teca Lewellyn, a Procter & Gamble Beauty Scientist. "So, depending on how frequently you wash your hair, it will take about a month to a month and half to gently fade away."

Here's how it works: Demi-permanent hair color molecules get under the outer cuticle of the hair shaft but, unlike permanent dyes, they don't penetrate

Banish dry skin, from head to toe.Have you ever counted how many steps you go through in your typical morning routine? From shower to hair and makeup, it's no wonder few ladies can make it out of the bathroom in less than 30 minutes. So it's only natural we often have the inclination to skip a couple steps where possible. For many of us, that means the body cream drops by the wayside. It's an easy compromise until one day you look down at your legs only to notice that skin looking rather reptilian.

MORE: Explore Your Best Body Skin Here

Skin's outermost layer, the stratum corneum, is protected by a lipid barrier made up of ceramides, cholesterol and fatty acids which helps keep water in the skin from leaching out. "The natural lipid layer can be lost during cleansing, so it's important to use a product that adds them back into skin," says Ellen Shepard, of Unilever research and development. That's where moisturizers come in-they treat dry skin, helping improve skintone and texture. Humectants (such as sodium

Pesticides are not just on your lawn, but in your home, too.You don't give much thought to toxins when you sip a glass of water, grab a receipt at your local grocery store or enjoy a barbecue on your backyard deck. And yet, in each of these instances, you and your family may be exposed to dangerous chemicals that could threaten your health.

Discover five common toxins that may be lurking in your bedroom, bathroom or backyard-and what you can do to protect yourself and loved ones.

1. Toxins: Air pollutants, including benzene and diesel

Why they're bad for you: "There is absolute proof that air pollution kills people-and it's ubiquitous," says Sandra Steingraber, Ph.D., an ecologist and author of "Raising Elijah: Protecting Our Children in an Age of Environmental Crisis." "Not only is air pollution linked to asthma and lung cancer, but it may also increase the risk for stroke, heart attack and diabetes." Plus, some new evidence shows that small transient exposure is associated with a greater risk than previously thought, she adds.

Is your polish non-toxic?When it comes to beauty products, few things are so obviously full of chemicals than nail polish and remover.

"Who hasn't walked into a nail salon and been overcome by the stinky punch of undeniable chemicals?" says Jenna Hipp, a "green" celebrity nail stylist in Hollywood, California. "You think to yourself: 'This can't good.' And you're right."

It's not just toxic fumes that should raise concern. It's the ingredients in your nail polish that are proven to be harmful. "Between the nail, cuticle and the surrounding skin, it's inevitable that what goes on your nails is absorbed through your blood stream," says Deborah Burnes, founder and CEO of Sumbody natural beauty line and author of "Look Great, Live Green."

Here are eight terms to brush up on before your next nail appointment.

MORE: Non-Toxic Nail Polishes - Our Favorite Brands

"3-Free" = no formaldehyde, toluene or dibutyl phthalate
Formaldehyde is the F-word of manicures-it's not necessary to use and if it is