10 surprising obesity facts

A BMI in the obesity range affects your health in surprising ways, from osteoporosis risk to your sex life.
© MSN Healthy Living // © MSN Health

Obesity affects health in some strange and surprising ways. It sabotages memory in older women, dilutes the effectiveness of the flu vaccine and can even wreck your sex life. It’s also unpredictable. Most people don’t continue to gain weight throughout life, for example. Read on for the latest scoop on obesity and new studies that show its impact on your health.

-- By Linda Melone for MSN Healthy Living

1 of 12 Overweight people (RONALDO SCHEMIDT/Getty Images)

Weight loss improves memory

Obese women who lose weight may notice an improvement in memory, according to a new (June 2013) study presented at the Endocrine Society’s 95th annual meeting.  Previous research shows obese people have an impaired ability to recall life events, such as a 2010 study from Northwestern Medicine that links memory loss to weight: the more an older woman weighs the worse her memory. The study, part of a larger study funded by the Swedish Research Council and the Swedish Heart-Lung Foundation, showed a one-point drop in memory score for each BMI point increase in a woman’s weight. The new Endocrine Society’s study shows this memory loss is reversible. Brain activity pattern during memory testing showed improvement in remembering and matching faces as the study participants’ average BMI dropped from 32.1 before the six-month diet to 29.2 BMI.

2 of 12 Man trying to remember (Juanmonino/Getty Images)

Obese people have weaker immune systems

Lower levels of vitamin D in obese people may affect the immune system and increase the risk for asthma and allergy, according to new research by The Endocrine Society.  Researchers found a link between the severity of a person’s obesity and certain biochemical measures of allergic disease. “As an inflammatory disorder (the fat around the midsection causes inflammation), obesity can affect anything from diabetes to asthma to cancer,” says Joseph Skelton, MD, an obesity expert at Wake Forest Baptist Medical Center. In addition, obesity may decrease the effectiveness of the influenza vaccine, according to a study published in the International Journal of Obesity (2012).

3 of 12 Checking temperature (Peter Dazeley/Getty Images)

Obesity wrecks your sex life

Hormonal changes associated with obesity can cause libido to drop in both men and women. “The balance of the sex hormones is a complex one,” says Dyan Hes, a pediatrician and obesity specialist on the American Board of Obesity Medicine. “In general, obese men have decreased testosterone levels and elevated estrogen levels, whereas obese women develop a hyperandrogenic (excess male hormone) state.”  This hormone imbalance in obese women leads to polycystic ovarian syndrome (PCOS) and includes symptoms such as excess body hair, irregular menses, acne, and ultimately contributes to infertility. Insulin levels mediate these changes, says Hes. “No one knows exactly at what level fat cells will lead to all these changes, although the higher the level of obesity, the greater risk of all these hormonal complications.”

4 of 12 Person sleeping (B2M Productions/Getty Images)

Obesity patterns appear early

Early childhood growth and feeding patterns may impact early childhood weight and obesity status, independent of the parents’ BMI, according to a study published in PLOS One, a peer-reviewed online publication. Obese children are more likely to become obese adults, according to the Centers for Disease Control and Prevention (CDC). Children who emptied their bottles by age two showed a 1.3 times higher risk of obesity risk. Researchers recommend promoting breastfeeding and increased feeding skills of caretakers as ways to intervene. A new study published in Pediatric Obesity backs this up. Researchers reported a 2.5 time higher obesity risk in formula-fed babies compared with breast-fed babies by the time the babies reached 24 months.

5 of 12 Baby (Mike Kemp/Getty Images)

Some people can’t stop eating

It’s normal to feel ravenous after skipping lunch or going all day without food, but people born with a rare genetic defect called Prader-Willi Syndrome (PWS) lack the ability to regulate their appetite. “They literally cannot stop eating,” says Cindy Heiss, PhD, RD, at the Metropolitan State University of Denver. “Prader-Willi Syndrome is characterized by such a voracious appetite for food (as a result of brain dysregulation of appetite) that individuals typically have to live in a special group home or institutional environment where access to food is strictly controlled.” Symptoms usually appear in children ages 1 to 4 and include constant craving for food and rapid weight gain along with poor muscle tone and lack of eye coordination.

6 of 12 Too much food (Jupiterimages/Getty Images)

Gases in a person's breath could predict obesity risk

Analyzing a person’s breath may indicate the likelihood of weight gain, according to a recent study published in the April 2013 Journal of Clinical Endocrinology & Metabolism. People with high concentrations of both hydrogen and methane gases in their breath are more likely to have a higher BMI and body fat percentage, the study found. The combination of the two gases indicates the presence of a microorganism that may contribute to obesity. “Obese people have different colonies and numbers of bacteria in their gut,” says Apovian.  “If they lose weight they have more of the lean person’s bacteria, although this is a research area we’re just starting to discover. We don’t yet know what comes first.” 

7 of 12 Gases in breath (Buena Vista Images/Getty Images)

Obesity ranks second among preventable causes of death

Obesity is second only to smoking as the most preventable cause of death, according to the CDC. Much of the illness related to chronic diseases traces back to a lack of physical activity and poor nutrition. Conditions related to obesity include high blood pressure, heart disease and stroke, type 2 diabetes, increased risk of gallstones and metabolic syndrome, a group of risk factors defined by a large waistline, high triglycerides, lower than normal HDL (good cholesterol), higher than normal blood pressure and higher than normal fasting blood sugar. In addition, obesity increases the risk of certain cancers, osteoarthritis, sleep apnea and reproductive problems.

8 of 12 Ambulance (Marje Cannon/Getty Images)

Obesity may increase risk of osteoporosis

Obesity was thought to be protective of bone loss, but new research shows the opposite may be true. A study published in the journal Radiology (July 2013) found that obese people with higher levels of fat in their muscle tissue, blood and liver also had higher levels of fat in their bone marrow, increasing the risk of osteoporosis. Earlier studies examined the relationship between bone mineral density and visceral fat (fat around the organs), where this study looked at fat inside the bone marrow, which produces stem cells responsible for bone formation. Higher levels of bone marrow fat puts people at increased risk of fracture, according to the study.

9 of 12 Osteoporosis (Chris Fertnig/Getty Images)

Older people are less obese

Changes in body fat and lean muscle associated with aging causes a gradual increase of body fat, a decrease in lean body mass (muscle) and an increase in body weight as we age.  After the age of 60 this trend declines slightly, especially among men. “It differs between men and women,” says Caroline M. Apovian, MD, director of the Center for Nutrition and Weight Management at Boston Medical Center and a leading obesity medicine specialist. “In general, everyone gains weight, but women continue to gain into their 70s before they start to drop off; this occurs earlier for men.” In addition to hormonal changes and the loss of muscle mass, a less robust appetite also contributes to this drop off in body weight. “Even if you’re thin you start to lose taste and sense of smell,” says Apovian.

10 of 12 Older man at doctor's office (BSIP/Getty Images)