Men and women are equal under the law (at least that is the ideal). But when it comes to health, there are some big differences between the sexes. Here are 12 facts all women should know about how women’s health differs from men’s health:

1.       Heart. Heart disease is the leading cause of death for women in the United States. Nearly five times as many women die from heart attacks every year than will die from breast cancer. Most people are aware of the signs of a heart attack—in men. In women, the symptoms may not be the same and are often harder to identify. Forty-three percent of women experience no chest pain at all during a heart attack. The top symptoms reported by women include:

• Shortness of breath
• Weakness
• Fatigue

Women sometimes experience pre-heart attack symptoms up to a month prior to the actual attack. These symptoms are not necessarily ones you would associate with a heart attack, and include:

• Unusual fatigue
• Sleep disturbance
• Shortness of breath
• Indigestion
• Anxiety

If you think you are experiencing a heart attack, call 911 immediately and crush or chew a full-strength aspirin and swallow with water.

2.     Sex. There is a generally-held belief that men hit their sexual peak at about 18, while women peak in their thirties. Studies do show that in men, testosterone levels drop 2% each year after they turn 30. Anecdotal evidence indicates that women may continue to peak for a long time, in part due to lessened childcare responsibilities, greater self-confidence, and other benefits of, if not getting older, at least not being young any more.

3.       Weight. It’s just so unfair—but women are more likely to be overweight than men. Women carry more fat than men naturally because it is essential for the energy needed to bear and nurse babies, so gaining weight just comes naturally to us. It also seems to be true that women have more difficulty losing weight. Men carry more muscle mass than women, and muscle mass is more metabolically active than fat. When women exercise, their burn rate is 37% lower than men, on average. So you can be doing all the same things as your hubby or significant other, and he’s going to be slimmer and trimmer than you. Just resign yourself to the awful truth, and eat less and exercise more than he does.

4.     Depression. Women are twice as likely as men to experience severe depression. Some of this gender gap may be due to women’s ever-changing hormones from puberty to menopause. The most critical symptom of depression is not feeling sad; most seriously depressed people report feeling nothing, or emotional numbness. Depression is treatable. In addition to seeing a doctor, exercise, good nutrition and good friends are important.

5.     Osteoporosis. Osteoporosis, or thinning of the bones due to loss of calcium, is far more prevalent in women than men. This is because estrogen plays a major role in the female body’s ability to absorb calcium. (Testosterone plays a similar, but less pronounced role in men.) There are usually no warning symptoms of osteoporosis until bones begin to fracture easily, so get a bone density scan on a regular basis once you start menopause. You can prevent osteoporosis by making sure you are getting enough calcium, either through supplements or in your diet. Women from 18 to 50 need 1,000 milligrams of calcium a day. When women turn 50, this should be increased to 1200 milligrams a day, according to the Mayo Clinic.

6.     Autoimmune disease. Three out of four people suffering from autoimmune disease are women. Autoimmune diseases occur when the body undergoes an immune response to its own tissues and naturally occurring bodily substances. Examples of this are lupus, eczema, and rheumatoid arthritis, but there are many more. There is nothing you can do to prevent an autoimmune disease, but many are either treatable or manageable.

7.     Drugs. When women get addicted, they experience more severe withdrawal symptoms than men and (perhaps as a consequence) find it more difficult to quit. Women produce less of the stomach acid required to break down ethanol and are the fastest-growing segment of the alcohol-abusing population in the U.S. Smoking has a more negative effect on cardiovascular health in women than in men.

8.     Pain. Women generally are more sensitive to pain than men. Women are also more likely to have chronic pain conditions such as fibromyalgia, migraine, osteoarthritis and rheumatoid arthritis.

9.     Life Expectancy. Women tend to live 7.1 years longer than men in the U.S. (which is behind Cuba in average life expectancy, according to the United Nations). Harvard researchers speculate this is because women experience menopause, which protects them from the risk of further childbearing so they can help with rearing grandchildren (the “Grandmother Effect”). Few other species menstruate, and they are all species where the young remain dependent longer on parents to survive.

10.  Menopause. Men’s bodies change gradually over time, but women’s life changes are more profound and dramatic—none more than the onset of menopause. As just mentioned, menopause protects woman from dangerous late-life childbearing. It also stops the production of the hormones estradiol and progesterone, which in turn eliminates the ripening of eggs and the growth of uterine lining. Estrogen levels drop, but continues to be produced by the ovaries, bone, blood vessels, brain, and fat tissues. The hormone testosterone also declines over time (in men as well as women). However, many women find they are delighted with the cessation of menstrual flow and seldom miss the abrupt mood swings that sometimes accompany menstruation.

11.  The X Factor. This refers to the fact that women have two X chromosomes and men have one X and one Y. Initial research indicates that the micro-ribonucleic acid (RNA) in the X chromosome plays a role in strengthening the immune system, enabling it to ward off diseases and even cancer. Because men have only one X chromosome, if something goes wrong, they have no backup. Scientists think this may be why women live longer and tend to be somewhat healthier than men—and may also be the reason women experience more autoimmune diseases than men.

12.  Heart Rate Variability. HRV is the variability in timing between one heartbeat and the next. This is a function of the “tug-of-war” between the sympathetic and the parasympathetic nervous systems. High variability (in microseconds; we’re not talking about afibrillation here) indicates good health and low stress. When stress is high or health is poor, the tug-of-war degrades, resulting in lower HRV. HRV tends to be somewhat higher in men than in women, though the reason for this is unknown. It is important to know that you can train yourself to raise your HRV—thereby lowering stress and increasing your resilience and energy. This can be done merely by doing measured deep breathing. SweetBeat™, the iPhone app from SweetWater Health, monitors HRV and helps train you to raise your HRV levels.