Your Healthiest Hair Ever

Healthy hair is thick from roots to ends. But aggressive brushing, heat styling, and chemicals used during coloring and straightening processes chip away at the cuticle, Cutler says. This is especially true for the ends, the oldest -- and therefore most vulnerable -- part of strands.

TEST: Pull back hair (into a ponytail if possible). If it's dramatically thinner at the ends compared to the roots, it's time to bulk up.

Whisk Away Weak Spots
A trim is the most crucial step to fending off frayed, uneven pieces of hair. "Damaged ends start a chain reaction," Cutler says. "A minor split end can continue moving up a mostly healthy piece of hair." Cutting away the fragile part puts a stop to breakage. A rule of thumb: Have your hair cut once every eight to 10 weeks.

Baby Wet Strands
Water temporarily weakens the protective chemical bond that helps hair stand up to aggressors. "That's why it's easier to break wet hair than dry," says Shannon Tor, senior project leader for Tresemme in Chicago. The healthiest way to detangle damp strands: Start an inch above the ends and remove knots in small sections, then move upward in one-inch increments until you reach the roots, Corbett suggests.

Fill Up on Protein
Conditioners containing amino acids as well as wheat, soy, or milk proteins plug holes along the cuticle, temporarily resulting in a thicker strand of hair. Proteins can be drying, however, so use them in moderation once or twice weekly, and find a formula (such as Pantene's) that also contains fatty alcohols or moisturizing lipids, such as ceramides or jojoba oil. Or consider a more potent salon treatment every other month. Redken Chemistry Extreme Shot Phase, $25, redken.com for locations, is packed with proteins and hydrators.