Thursday, October 18, 2018

Internal and External Factors in the Obesity Epidemic

Obesity is undeniably one of the growing concerns, that for the most part, go largely unaddressed. Positive body image movements, largely US-centric, have expanded into the mainstream, where one’s own body may be considered a political statement against the beauty norm of “thin”. One of these movements, Healthy At Every Size, proposes that regardless of your weight, you are healthy no matter your weight, which much evidence weighs against such claims. People in the overweight or obese categories of BMI, or those with more adipose tissue, are at higher risk of heart disease. Despite all scientific evidence, why has the HAES movement gained such prevalence? There is no denying that the obesity epidemic in the US has gotten progressively worse in the past couple of decades— data maps from the CDC show an exponential growth of adults who have obesity in just 5 years alone.

Many people believe that their weight is outside their sphere of influence, pointing fingers to one unchangeable factor they claim is responsible for their ballooning weight and inability to shed weight: genetics. To an extent, they are correct. In Dr. Beshel’s study of Drosophila fruit flies, the fly leptin analog unpaired 1 showed that obesity could be genetically induced. With unpaired 1 disrupted, the flies showed more attraction to food, increased food intake, and thus gained weight. Of course, there may be genetic predispositions, or even epigenetic markers that make one more predisposed to food-seeking behaviors; hormonal changes or irregularities may even be at play. However, in the end, these should not be excuses to remain at-risk for many health problems. Obesity costs the economy millions of dollars to address concerns that come with all the excess adipose: costs of medication, disability benefits from debilitating effects of extra fat, and lowered rates of productivity. But there’s more to gaining weight than just genetic— the effect food has on the brain is also observable.

A study published in the American Journal of Clinical Nutrition by Stice, Burger, and Yokum studied the brain’s response to high-fat or high-sugar content. Subjects drank milkshakes with equal amounts of calories, but varied in their sugar and fat content. Using functional MRI techniques, they were able to see the real-time effects of high-sugar or high-fat in various brain areas associated with reward, gustation, and somatosensation. Their results suggested that the high-fat taste “prompted greater activation in regions involved in associative learning processes (caudate and hippocampus) and somatosensory regions (postcentral gyrus)” (Stice et al.)— possibly the association of high-satiety to the milkshake, whereas tastes of high-sugar prompted greater activation in regions associated with reward and motivation, driving the addictive characteristic of sugary food. It feels good; you want more. Sugar is not without calories of its own.

In the end, the only proper way to tackle this epidemic is to change and regulate the food environment in which lurks the greater evils of calorie dense, high-sugar and high fat foods, and the environment in which our attitudes around food revolve around. By including in a way that benefits children’s food behavior well into adulthood and teaching restraint around indulgent foods, challenging the system from inside out will no doubt benefit society as a whole.

Works Cited:

Beshel, J, et al. “A Leptin Analog Locally Produced in the Brain Acts via a Conserved Neural Circuit to Modulate Obesity-Linked Behaviors in Drosophila” (10 January 2017)
https://www.sciencedirect.com/science/article/pii/S1550413116306465?via%3Dihub

Centers for Disease Control and Prevention: Nutrition, Physical Activity, and Obesity: Data, Trends and Maps" (2016)
https://nccd.cdc.gov/dnpao_dtm/rdPage.aspx?rdReport=DNPAO_DTM.ExploreByTopic&islClass=OWS&islTopic=OWS1&go=GO

Eckel , N. et al. “Transition from metabolic healthy to unhealthy phenotypes and association with cardiovascular disease risk across BMI categories in 90 257 women (the Nurses' Health Study): 30 year follow-up from a prospective cohort study” (30 May 2018)
https://www.thelancet.com/journals/landia/article/PIIS2213-8587(18)30137-2/fulltext

Stice E., et al. “Relative ability of fat and sugar tastes to activate reward, gustatory, and somatosensory regions” (1 December 2013)
https://academic.oup.com/ajcn/article/98/6/1377/4577250

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