The September 30, 2012 issue of the Chicago Tribune ran an article by reporter Julie Deardorff entitled “In battle against bulge: calories aren’t the only enemy.” While increased food consumption and decreased physical exercise explains most of globesity—the skyrocketing percent of overweight and obese consumers worldwide— the author points out that obesity is complex condition involving multiple genes and pathways.
Deardorff notes that studies have identified nearly a dozen factors besides overeating and inactivity that may contribute to being overweight. Some are as follows.
- Air pollution. Pregnant mothers may predispose their babies to obesity when they breath high levels of polycyclic aromatic hydrocarbons (PAHs). These are a group of over 100 compounds that are byproducts of burning coal, oil, gas, tobacco and garbage including cigarette smoke, grilled meats to burning candles and incense. One study with humans was published in the June issue of the American Journal of Epidemiology (1).
- Gut bacteria. Bacteria in the gut impact how food is digested. Research shows that changing the mix of microbes in the gut can lead to increased weight gain. For example, antibiotics given to infants less than six months old may increase the likelihood the child will be overweight. (No such correlation was found with antibiotics given to older babies age 6 to 14 months old.) (2)
- Sleep deprivation. Lack of sleep, say less than five or six hours per night, can alter hormone levels that control hunger (3). It may also decrease resting metabolic rates. One study also showed those that lacked sleep had higher blood glucose levels after a meal, which is associated with diabetes, a condition related to obesity.
Deardorff went on to list other factors that researchers suspect in may influence our weight. Older, more overweight moms have children that are more likely to be obese. Both are trends in many countries. The increasing level of carbon dioxide in the air may make blood slightly more acidic which causes appetite-related neurons in the brain to “fire more frequently.” People are keeping indoor temperatures warmer than in the past. In Britain in 1978, the average living room temperature was 64.9 degrees F, in 2008 it was 70.3 degrees. People generate extra heat in cooler rooms, without necessarily shivering. Decreased smoking, viruses, pharmaceutical drugs, and air conditioning (keeping people indoors during hot months where they exercise less), were additional factors.
None of this lets over-consumption of food off the hook, but it does show that weight management is a challenge indeed.
(1) Rundle, A, et al. 2012. Association of childhood obesity with maternal exposure to ambient air polycyclic aromatic hydrocarbons during pregnancy. Am J Epidemiol. 175(11):1163-72.
(2) Trasande L, et al. 2012. Infant antibiotic exposures and early-life body mass. Int J Obes (Lond). Aug 21, doi:10.1038/ijo.2012.132
(3) Kristen Knutson, K. 2012. “Does inadequate sleep play a role in vulnerability to obesity?” The American Journal of Human Biology, Wiley-Blackwell, January 2012, DOI: 10.1002/ajhb.22219