Not everyone has the same risk of obesity. Some factors that can make you likely to be overweight or obese include:
Genetic Factors. Research suggests that genes, which give the body directions for responding to its environment, can influence several obesity-causing factors including the amount of body fat you store, where that fat is distributed, how efficiently your body converts food into energy, and how your body burns calories during exercise. Most recently, a team of international scientists has found that the AMY1 gene, which controls the production of an enzyme found in saliva, is strongly correlated with obesity risk. Individuals with less than four copies of the AMY1 gene are eight times as likely to be obese than individuals that who have more copies. According to the federal Centers for Disease Control (CDC), genes are also responsible for varying capacities for hunger and caloric intake. But genetic factors, the agency says, can’t be completely blamed for obesity. Genetic changes happen too slowly in the human population to be responsible for the fast-spreading “obesity epidemic” in the world, the CDC says. Instead, the agency cites increased inactivity and increased consumption of calorie- and fat-laden foods as the driving force behind the epidemic.
Family and Friends. A study by researchers from Harvard University and the University of California in San Diego found that if one sibling became obese, the odds of another sibling becoming obese increased by 40 percent. The same analysis found that if one spouse became obese, the odds that the other spouse would do the same increased by 37 percent. Scientists theorize that over time, a social or familial network changes what people see as usual and acceptable.
Physical Inactivity. When we take in more calories than we burn, we gain weight. The less active we are, the harder it is to burn those excess calories. The American Heart Association reports that sedentary jobs have increased by 83 percent since 1950, and physically active work now only accounts for 25 percent of jobs. Additional factors in the sedentary inactivity epidemic include improved transportation technology. From subways to automobiles to escalators, walking is becoming less and less a part of daily life. Overall, the AHA says, “the consequences of physical inactivity are staggering.”
Unhealthy Eating Habits. Although it’s a well-established fact that having a high-fat, high-calorie eating pattern promotes weight gain and is almost certain to lead to obesity, the reasons behind our unhealthy eating habits are complex. It’s not just lack of “willpower” that drives us to eat unhealthy foods: A recent study conducted in Belgium found that high-fructose corn syrup has the same addictive effects as cocaine on the brains of the mice the researchers studied. Over the past decades, Americans have been subjected to a never-ending bombardment of advertising promoting convenient but unhealthy foods. Marion Nestle, editor of the 1988 Surgeon General’s Report on Nutrition and Heal Weight Gain, cites Big Food’s targeted campaigns to minorities and children as examples of the industry’s lack of commitment to good health. Further, portion sizes have grown in restaurants. According to the National Heart, Lung and Blood Institute, part of the National Institutes of Health, portions today are equal to what would have been meals for two or three people twenty years ago.
Pregnancy. Ideally, a woman’s weight should increase 25 to 35 pounds during pregnancy, according to the federal National Library of Medicine (NLM). The agency says that much of the normal weight gain stems from the baby itself, as well as the placenta, amniotic fluid and increases in the amount of breast tissue, blood supply and fat stores. Women who are already obese when they become pregnant, or become obese during pregnancy, are at risk for a number of serious conditions. For women who are overweight prior to pregnancy, weight gain should be constrained to be more modest, because the risk of becoming obese is much higher. The federal Centers for Disease Control (CDC) lists some of the potential problems as stillbirth, cesarean deliveries and the baby being born with diabetes. Up to 10 percent of women may suffer an excess level of hormones that released by the thyroid gland after pregnancy. That usually causes mild hypertension, but the condition isn’t permanent. The National Institute for Diabetes and Digestive and Kidney Diseases (NIDDK), part of the National Institutes of Health (NIH), says that other obesity-related hormones, including leptin and ghrelin, are genetic and can cause chronic obesity. But there is no evidence that levels of this hormone increase during pregnancy. The bottom line for post-childbirth weight gain: extra pounds is not inevitable; experts universally say that eating well and exercising can help you manage your weight.
Lack Of Sleep. The Landmark Nurses’ Study found a distinct link between lack of sleep and obesity. The investigation followed 60,000 nurses for 16 years. At the beginning of the study period, none were obese. But after 16 years, women who slept five hours or fewer per night had a 15 percent higher chance of becoming obese than those who got enough sleep. Experts cite several reasons for the link between weight and lack of sleep. People who don’t get enough sleep may be too tired to exercise. They also may eat more than people who are well rested because they are awake for more hours and because appetite-controlling hormones are disrupted by the lack of sleep. Other irregular eating patterns, such as skipping breakfast, may also lead to weight gain.
Several types of medications can lead to weight gain, including some antidepressants, anti-seizure medications, diabetes medications, antipsychotic medications, steroids and beta blockers. According to experts from the Johns Hopkins School of Medicine, the reasons for medication-related weight gain aren’t always clear. Some drugs may cause an increased craving for food, leading to overeating, and other medications, can lead to fatigue, which is likely to make a person less active. The Hopkins team also reports that weight gain is so common among Americans that it’s often impossible to single out a medication as a cause.
Generally, rates of obesity are highest during adulthood, specifically ages 50+. About 1 in 3 (approx. 30%) of American adults are obese, however this rate is higher for those who were obese as school-age children. One study found that about half (42 to 63%) of obese school-age children go on to be obese adults. The percentage of older people – age 65 and over – is more than one third, according to the Centers for Disease Control. The problem of obesity in older age may be aggravated by a reduction in what is already inadequate physical activity.
Illnesses and Health Conditions. Diseases that are linked to obesity include: Heart disease, high blood pressure, type 2 diabetes, cancer, osteoarthritis, depression and sleep apnea, according to the federal Centers for Disease Control (CDC). Other illnesses linked to obesity include Prader-Willi syndrome, hypothyroidism and Cushing’s syndrome. There may also be a link between obesity and smoking. According to the National Library of Medicine, one study found that obese smokers tended to have higher levels of fat accumulation than obese nonsmokers.
Improper Prenatal and Postnatal Care. According to the Harvard School of Public Health, factors influencing obesity begin in the “intra-uterine environment” and help shape the “trajectory of weight gain…throughout the life course.” Prenatal factors that influence an offspring’s obesity include the mother’s weight gain and blood sugar levels throughout pregnancy. Developing pregnancy-related (gestational) diabetes is especially harmful. Although it might seem like common sense to assume that the quality of a mother’s diet during pregnancy would affect her offspring’s weight, Harvard says no concrete relationship between the two has been established. A Harvard study published in 2007 found that children of mothers who gained an excessive amount of weight during pregnancy had four times the risk of being overweight at age three than children who were born to mothers who gained an “inadequate” amount of weight during pregnancy.