-- intro: By now you’ve probably heard that obesity increases the risk of heart disease and diabetes. But you might not know that the extra weight can have other serious health consequences, including cancer.
A new study found that 10 percent of all gallbladder, kidney, liver, and colon cancers could be attributed to excess weight. A whopping 41 percent of uterine cancers were tied to obesity, according to the study published today in The Lancet.
Read on to learn eight surprising effects of obesity.
quicklist: 1category: Surprising Effects of Obesitytitle: Cancerurl:text: The Lancet study of 5.4 million people found that every 1-point population-wide increase in body mass index or BMI would result in 3,790 additional cancers each year. That’s worrying, considering that the average BMI in the U.S. has risen nearly 2.5 points for men and almost four points for women since 1971, according to a 2013 study.
The National Cancer Institute estimates that obesity contributes to 34,000 new cases of cancer in men and 50,000 in women each year. But if every adult reduced their BMI by 1 percent – a loss of roughly 2.2 pounds – about 100,000 new cases of cancer could be avoided, according to the agency’s website.
quicklist: 2category: Surprising Effects of Obesitytitle: Migrainesurl:text: A study published in the journal Neurology revealed what a real headache carrying extra weight can be.
Johns Hopkins researchers surveyed nearly 4,000 people to find that the higher their body mass index, the greater their chances were of having episodic migraines. Those who were obese were 81 percent more likely to experience at least 14 migraine headaches each month compared to people who were a healthy weight. Obese women over the age of 50 suffered from chronic headaches the most.
quicklist: 3Category: Surprising Effects of ObesityTitle: Infertilityurl:text: Overweight women have a harder time getting pregnant. One Indian study of 300 morbidly obese women found that over 90 percent of them developed polycystic ovarian disease, a condition associated with infertility, over a three-year period.
As with cancer, the association between obesity and infertility isn't entirely clear.
"Obesity is an inflammatory state and that alone might decrease fertility," noted Dr. Marc Bessler, director of the Center for Weight Loss and Metabolic Surgery at New York Presbyterian Hospital at Columbia University Medical Center. "It may also be the result of hormone changes produced by the fatty tissue."
Bessler said that many of his heavier patients experienced difficulty getting pregnant. And many infertility clinics don't accept female patients with high body mass indexes given their diminished chances of conceiving. However, Bessler said some of his patients become pregnant just months after weight-loss surgery once they had dropped a few pounds.
quicklist: 4category: Surprising Effects of Obesitytitle: Premature Birth url:text: For heavier women who do get pregnant, the worries aren't over. A study in the Journal of the American Medical Association found that obesity increases a woman's chance of having a pre-term baby, especially when her body mass index is 35 or higher.
The study's authors speculate that having too much fat may inflame and weaken the uterine and cervical membranes. Whatever the reason, it can have devastating effects. Premature birth is the leading cause of infant death and long-term disabilities.
quicklist: 5category: Surprising Effects of Obesitytitle: Sleep Disordersurl:text: Sleep and excess weight do not make good bedfellows. Nearly 80 percent of older, obese Americans report having problems with sleep, an American Sleep Foundation survey found.
Poor sleep contributes to a host of diseases including diabetes, heart disease and, ironically, obesity itself. Numerous studies link short sleep to expanding waistlines, including the Harvard Nurses' Study, which found that those who slumbered less than five hours a night were 15 percent more likely to gain weight than those who enjoyed at least seven hours of sleep.
"Sleep apnea can be caused by increased fat around the neck area that presses down and closes off the soft tissues of the airways while a person is lying down, especially on his back," Hensrud said. "This means the person does not get good quality sleep, has less oxygen in the blood stream, and the heart has to work harder."
quicklist: 6category: Surprising Effects of Obesitytitle: Bullyingurl:text: Though fat people are often the butt of the joke, obesity stigma is no laughing matter.
A Yale study found that weight is the number one reason people are bullied at any age and those who are bullied have lower self-esteem, higher levels of depression and increased risk of suicide.
The main source of ridicule, according to the Yale researchers: Loved ones.
"More than 40 percent of children who seek treatment for weight loss say they have been bullied or teased by a family member," said the study's lead author, Rebecca Puhl. "When we asked obese women who stigmatized them the most, 72 percent said it was someone in their family."
Puhl said discussions with loved ones about their burgeoning weight often come across as judgmental and derogatory, even when intentions are good. However, offering support and encouragement is the most effective approach to help someone struggling to drop off pounds.
quicklist: 7category: 8 Surprising Effects of Obesitytitle: Difficulty Finding Doctorsurl:text: The number two source of stigma, after loved ones?
Puhl said her studies have found that 67 percent of overweight men and women report being shamed or bullied in the doctor's office. And 50 percent of doctors found that fat patients were "awkward, ugly, weak-willed and unlikely to comply with treatment" while 24 percent of nurses said they were repulsed by their obese patients.
A negative reception from a healthcare provider is especially detrimental to obese people, Puhl stressed, because they already contend with a greater number of health problems than average.
"Besides jeopardizing discussions between patients and healthcare providers, someone who is obese is more likely to avoid the doctor altogether even when they have a problem," she said.
However Puhl noted that the knife cuts both ways. Her studies reveal that people are less apt to follow doctor's orders and more likely to switch to a new provider if their physician is overweight.
quicklist: 8category: 8 Surprising Effects of Obesitytitle: Smaller Wagesurl:text: Wider waistbands seem to widen the pay gap.
One George Washington University School of Public Health study found a strong connection between greater obesity and shrinking wages. Examining data from the 2004 National Longitudinal Survey of Youth, the researchers discovered that wages among the obese were $8,666 less for females and $4,772 lower for males compared with their thinner counterparts. In 2008, the researchers found wages were $5,826 less for obese females -- a 14.6 percent penalty over normal-weight females.
Slimmer females, especially, do seem to have fatter wallets. In a University of Florida study, women who weighed 25 pounds less than the group average, earned $15,572 a year more than women of normal weight and women who tipped the scales at 25 pounds above the average weight earned an average of $13,847 less than an average-weight female. They found no such disparity among men.
A version of this story previously ran on ABCNews.com.