When Melanie Sahli and Ann Ross of Arizona improved their eating habits to lose weight, they also gained a few things, including glowing skin and healthier hair.

Registered dietitian Elizabeth Somer isn't surprised.

"Your hair and skin and nails are just an outer reflection of your inner health," she says from her office in Salem, Ore. "Everything you need to make your skin healthy, your hair shiny and your nails strong are, lo and behold, also the nutrients that will protect your heart from heart disease, your breasts from cancer and your brain from memory loss."

Somer, author of "10 Habits That Mess Up a Woman's Diet" (McGraw-Hill, 2005, $16.95) and "Age-Proof Your Body" (McGraw-Hill, 2006, $18.95), says looking in the mirror can tell you what's wrong with your diet and direct you to the solution.

Excess weight may be only the most obvious clue. Wrinkles, chipped fingernails and crankiness also can be signs of a poor diet.

"I see women spending hundreds of dollars on creams and other beauty products," she says, "when the first place to start to nourishing your skin or hair or nails is on the inside."

Eating carrots, for example, deposits health-bestowing beta-carotene in your skin tissues, addressing more than just the surface of your skin, as a beautifying cream does, she says.

Beta-carotene, an antioxidant that may help prevent DNA damage, is a highly pigmented compound present mainly in orange, deep-yellow and dark-green vegetables and fruits. So although sunscreen and a hat protect your skin from the outside, colorful produce builds your body's defenses against sun damage from the inside, she said.

Excess weight, aching knees and shortness of breath are what drove Sahli, 54, to join Weight Watchers.

But after losing about 60 pounds in 17 months, she found surprising energy and other improvements in her well-being.

"Emotionally, I'm happier," says Sahli, of Phoenix, "and I can't even tell you the last time I had a cold. My hairdresser noticed that my hair was growing faster. I really was getting healthier from the inside out."

In addition to eating more-nutritious foods, Sahli became conscientious about drinking water and taking a multivitamin every day.

"I used to think water was a waste of time," she says, "but I noticed that I didn't have as much trouble with dry skin over the winter because I was staying hydrated."

Ross, of Tempe, Ariz., also stepped up her water intake when she started following the Weight Watchers plan.

Cutting sugar from her diet and lowering fat intake, Ross lost almost 40 pounds in about seven months. Her skin feels softer now, and people express surprise when they learn she's 62.

Dietitian Somer would credit foods rich in iron and certain B vitamins, especially folic acid, B-6 and B-12, with much of the women's good health. The nutrients help maintain healthy red blood cells, circulate oxygen and nutrients through the body and remove waste products.

"If your circulation is short of optimal," she says, "you're going to notice, for instance, that your hair is dry and lifeless and lacks the luster you'd like it to have."

Somer also recommends omega-3 fatty acids, especially docosahexaenoic acid, or DHA, to prevent and correct diet-caused ills.

Eating cold-water, fatty fish rich in DHA omega-3, including salmon, cod, mackerel, sardines and tuna, may reduce risks for skin cancer, vision loss, heart disease, rheumatoid arthritis, memory loss and Alzheimer's disease, she says. Or try products such as soy milk and eggs that have been fortified with DHA.

"You see somebody whose grocery cart is loaded with tofu and fresh vegetables and soy milk and whole-grain bread," Somer says, "and their skin's glowing and their hair's shining, and they're at a healthy weight. They look like the food they eat."

Join our discussion: http://forums.hawaiimoms.com/viewtopic.php?t=1072">You really are what you eat.