Nancy Gottesman

You hear about it in the news a lot: the obesity epidemic. In the U.S., almost 75 million adults and 12 million children are obese. And these hefty numbers don't include the 33 percent of Americans who are merely overweight.

What exactly does this mean? The Centers for Disease Control and Prevention (CDC) defines obesity as having a body mass index (BMI) of 30 or higher. Just so you can visualize: a 5-foot-5-inch person becomes obese at 180 pounds. A BMI of 25-29 puts you in the "overweight" category.

But is obesity really so bad? The resounding answer is "Yes!"

In case you need convincing, here are 10 sobering reasons to lose weight:

1. Heart Disease

Excess fat, especially at your waist, raises triglyceride and bad cholesterol levels, lowers good cholesterol, increases blood pressure and damages your blood vessel system -- all of which put you at greater risk for cardiovascular disease, heart attack and stroke.

2. Cancer

Obesity is linked to increased risk of cancers of the esophagus, breast (postmenopausal), endometrium (the lining of the uterus), colon, rectum, kidney, pancreas, thyroid and gallbladder, and possibly other types of cancer as well, according to the National Cancer Institute.

3. Diabetes

The most common form of diabetes, Type 2, develops most often in middle-aged men and women who are overweight or obese -- especially when those excess pounds manifest as belly fat. But adults aren't the only ones at risk. Type 2 diabetes is becoming more common among overweight and obese children and teens as well.

4. Heartburn

Norwegian researchers have found that gastroesophageal reflux disease (GERD) has increased by almost 50 percent in only 10 years. The reason? The rise in obesity. "Increased weight -- especially abdominal obesity -- increases the pressure over the lower esophageal sphincter, which is the closure mechanism between the stomach and esophagus," explains study author Dr. Eivind Ness-Jensen, senior resident in internal medicine and gastroenterology at Levanger Hospital in Norway. "The pressure forces the sphincter to open more frequently and for longer durations, promoting reflux of acidic content from the stomach to the esophagus."

5. Immunity and Influenza

As rates of obesity continue to rise, the number of deaths from the flu could rise too. Recent research from the University of North Carolina at Chapel Hill shows that obesity is associated with an impaired immune response to the influenza vaccination.

6. Depression

Obesity in women is linked to a 37 percent increase in major depression, and the two conditions often trigger and influence each other. Heavy women also have more frequent thoughts of suicide, according to the American Psychological Association.

7. Disability

No surprise here. Carrying around excess weight puts a lot more stress on your skeleton and limits mobility. According to the CDC, people with arthritis are more likely to be obese. What's more, Americans over the age 50 will collectively lose the equivalent of 86 million healthy years of life due to the combination of obesity and knee arthritis, say researchers at Brigham and Women's Hospital in Boston. And scientists at the University of New Hampshire found that overweight and obese women had an average of 24 percent less leg strength and 20 percent slower walking speed than normal-weight study participants.

8. Gum Disease

Too much body fat can even affect your oral health, putting you at higher risk for periodontal disease, according to a recent study conducted at the University of North Carolina School of Dentistry.

9. Infertility, Gestational Diabetes and Birth Defects

Heavy women experience more miscarriages and pregnancy complications (such as gestational diabetes and preeclampsia) and are more likely to give birth to babies with birth defects. In addition, obesity can lower the success rate of in vitro fertilization (IVF). A man's fertility suffers too: Obesity is associated with low sperm motility and altered testosterone levels.

10. Quality of Life

Duh! Chronic disease, disability, depression and other health problems all chip away at joie de vivre and longevity. According to research in the American Journal of Preventive Medicine, obesity significantly reduces "quality adjusted life years," due to poor health and premature death caused by excess pounds.

And if individual health woes don't provide enough reasons to lose weight, consider the fact that obesity can have a tremendous impact on the pocketbook as well. According to a new study from Cornell University, obesity now accounts for almost 21 percent of all U.S. health care costs. Nationwide, that translates to $190.2 billion per year. Individually, obese people incur $2,741 more per year in medical costs than non-obese people. In fact, obesity now adds more to health care costs than smoking cigarettes!

So if you've been ignoring those extra pounds, it's time to open your eyes. The best reasons to lose weight are simple: long life, good physical health and emotional well-being. And a little extra financial security doesn't hurt, either.