No body part gets more attention, but there's still so much to know. Discover the scoop on everything from sag to suspicious lumps in this chest cheat sheet.

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Getty ImagesPerky or pendulous, AA or DDD—our boobs come in a seemingly infinite variety of shapes and sizes. Each pair is beautifully unique, of course. And yet many of us wonder about the exact same things: "Why do my breasts sometimes hurt?" "Why can't I find a bra that fits?" "Should I be concerned about this lump?" Worry not: We've got answers to your most pressing breast-related FAQs—so you can give your girls all the support they need.

FAQ No. 1: What should I eat to keep my girls healthy?
Suzanne Dixon, RD, an epidemiologist and dietitian in Portland, Ore., advises eating a wide variety of plant-based foods, including these:

Nuts: "All varieties are rich in phytosterols, which have been shown in lab and animal studies to inhibit tumor development," Dixon says. And some types (including walnuts and pecans) contain fatty acids that may help reduce PMS-related soreness.

Cruciferous vegetables: Cabbage, broccoli, kale and Brussels sprouts are all chock-full of glucosinolates; these chemicals break down into compounds that appear to inhibit the development of cancer cells.

Mushrooms: Women who ate 10 or more grams of fresh fungi a day (about the size of a single white mushroom) had a 64 percent reduced risk of breast cancer, according to a 2009 Chinese study.

Legumes: Beans and lentils are also loaded with phytosterols. A Harvard University study showed that women who ate legumes at least twice a week had a 24 percent lower risk of breast cancer than women who ate them less than once a month.

FAQ No. 2: Help! Why are my breasts heading south?
Here are a few myths and facts about what causes your dynamic duo to droop.

You're getting older
TRUE. The ligaments that help give breasts their shape are made of collagen and elastin, which break down as you age.

You don't always wear a bra
FALSE. "A bra will hold up your breasts temporarily, but it can't prevent sagging," says Dan Mills, MD, vice president of the American Society for Aesthetic Plastic Surgery. Exception: a sports bra. Bouncing during workouts can make connective tissue deteriorate over time.

You liked tanning
TRUE. Ultraviolet rays break down collagen, Dr. Mills says. More reason to slather on SPF!

FAQ No. 3: Should I get an ultrasound, too?
If you have dense breasts, it's harder for a radiologist to spot signs of cancer on your mammogram. But a study published in February estimated that performing supplemental screening ultrasound on 10,000 women with dense breasts and negative mammos would prevent only about four deaths and would require about 3,500 unneeded biopsies. A potential alternative: tomosynthesis, an advanced type of digital mammogram that's becoming increasingly available. It generally improves detection rates and decreases false positives, says Barbara Monsees, MD, spokesperson for the American College of Radiology.

Next Page: What really affects my risk of breast cancer? [ pagebreak ]
FAQ No. 4: What really affects my risk of breast cancer?
Booze? Birth control? BRCA genes? An oncologist ranks some top concerns on a scale of 1 to 3.

Being overweight: 3
Your weight is especially crucial in the postmenopausal period. "Before, most of your estrogen is produced in your ovaries," explains Therese Bevers, MD, medical director of prevention at the University of Texas MD Anderson Cancer Center in Houston. "But after menopause, most of your estrogen is produced by fat cells, so the more fat you have, the more estrogen."

Lack of exercise: 3
An estimated 49,000 cases of breast cancer a year are linked to a sedentary lifestyle, according to research presented at the 2011 annual meeting of the American Institute for Cancer Research.

Your Age: 3
About two-thirds of invasive breast cancers are found in women age 55 or older.

Genetics: 3
Up to 10 percent of cases are thought to be hereditary.

Alcohol: 2
Research shows that sipping two or three drinks a day increases risk by 20 percent.

Fat intake: 1
In a 2014 study, women who ate the most saturated fat had a 28 percent higher risk of hormone receptor–positive cancer. "But factors beyond diet may have played a role, too," Dr. Bevers says.

The pill: 1
While women taking oral contraceptives have a slightly higher risk, their odds drop back to normal after 10 years of stopping.

Parabens: 1
These preservatives, found in some cosmetics, may act like estrogen in the body, which has raised concerns that they could spur the growth of breast cancer cells. But the FDA says parabens are present in beauty items in such small amounts, there's no need to worry.

Insomnia: 1
Some research has suggested a link between lack of shut-eye and breast cancer, but a reassuring 2013 Australian study found no connection.

FAQ No. 5: One side is bigger than the other. Is this normal?
Yes, you are not alone. Unevenness is a very common issue. And it may become more pronounced for women who have nursed. "The breast the baby preferred tends to be more stretched out," explains Jennifer Walden, MD, spokesperson for the American Society for Aesthetic Plastic Surgery. If the difference is noticeable, consider getting a bra with stretch cups so you can customize the fit. Or buy padded bras with removable pads.

FAQ No. 6: How much would I need to weigh to increase my risk of breast cancer?
As you get older, your goal should be to stay as close as possible to what you weighed during your senior year of high school (or below, if you were overweight as a teen). Research from the American Cancer Society has shown that women who gain 60 or more pounds after age 18 are two times as likely to develop postmenopausal breast cancer as women who still fit into their prom dress. Other research has shown that even gaining 20 pounds is linked to an increased risk of about 15 percent. (What's still unclear is whether a woman who has been overweight her whole life has the same level of risk as one who put on pounds through adulthood.) But Dr. Bevers offers some reassurance: "If, like most women, you have gained weight, don't panic. Just do your best to get rid of it."