Obesity Epidemic and Junk Food Consumption Go Hand in Hand

Nancy A. Melville

January 10, 2020

Mounting evidence shows that the obesity epidemic — and rise of related chronic conditions — corresponds with the increased intake of ultra-processed food, particularly in lower socioeconomic classes, but clinicians can play a role in turning the tide by using key strategies to help patients curb their consumption, according to a new review.

"The epidemic of obesity correlates directly with the pervasiveness of chronic diseases," the US authors write.

"Rather than simple secondary treatment of diseases with medications alone, we must transition our efforts to food as medicine as well," they add.

The review, published in Current Treatment Options in Gastroenterology, notes alarming data from the Centers for Disease Control and Prevention showing the prevalence of obesity in the United States in 2015-2016 to be more than a third of the population — 39.8%.

Of the multitude of issues in grappling with the epidemic is the question of food quality versus quantity, and whether "the food source of calories matter — or are all calories created equal?" write the authors, Janese Laster, MD, and Leigh A. Frame, PhD, of The George Washington School of Medicine & Health Sciences, in Washington, DC.

"It is essential to study the trends in types of food consumed to determine the major contributors to the obesity epidemic and chronic disease states," they add.

"Food as Medicine"; Processed Food Intake Leads to Fiber Deficits

In looking at the changes in food consumption that have paralleled the rising obesity prevalence, one indisputable trend is the increase in the consumption of ultra-processed or "junk" foods, and evidence supports a link between the two.

In mice and in vitro trials, emulsifiers, found in highly processed foods, have been shown to alter microbiome compositions, elevate fasting blood glucose, cause hyperphagia, increase weight gain and adiposity, and induce hepatic steatosis.

And recent human trials have found ultra-processed foods contribute to decreased satiety, increased meal eating rates, worsening biochemical markers, and more weight gain.

Notable research includes a study of three cohorts of healthy volunteers who were prospectively followed from 1986 to 2006 and from 1991 to 2003.

With an average weight gain among all participants over 20 years of 16.8 pounds, the study showed weight gain was positively associated with increased consumption of processed foods such as potato chips, sugar-sweetened beverages, refined grains, and processed meats.

Meanwhile, there was an inverse association with weight gain and increased intake of minimally processed foods such as vegetables, grains, nuts, and yogurt.

Additional studies have shown differing trends according to socioeconomic class, with small incremental improvements in dietary quality in higher socioeconomic groups; however, even in those groups, increases in servings of processed foods have been observed, say the review authors.

Ultra-processed food consumption is also linked to deficits in dietary fiber, which may explain notably insufficient fiber intake rates in the US population overall, the authors note.

Although the recommended daily fiber intake is 14 g/1000 calories, or approximately 25 g for women and 38 g for men, data from the National Health and Nutrition Examination Survey (NHANES) showed the average daily fiber consumption in 2009-2010 was just 17 g/day, with substantially higher consumption among men than women.

Lower fiber consumption has also been reported among black adults and those with lower family income.

Fiber deficits have important implications, as high fiber diets are linked to health benefits including the prevention of precancerous lesions, cancer, cardiovascular disease, type 2 diabetes, and Crohn's disease, as well as reductions in mortality, the authors note.

Lessons From the "Blue Zones" and Advice for Clinicians

Lessons from the so-called "Blue Zones" — five regions where populations consistently live over the age of 100 without chronic disease, such as indigenous South Americans and Mediterranean populations — provide insight. These populations, who have low meat intake, high fiber intake, and eat minimally processed foods, have far less chronic disease and obesity, and live longer disease-free, compared with the typical US population.

This offers insights into the dietary and lifestyle practices that appear most beneficial, say Laster and Frame.

In addition to showing better fitness, social interaction, and relatively lower stress, these populations have dietary commonalities of eating until 80% full, eating mostly plant-based proteins including beans (meat up to five times per month), and moderate daily drinking with friends, the authors write.

For the vast majority of individuals who reside outside of Blue Zones, the authors recommend key strategies for clinicians to help steer individuals towards the evidence-based improved dietary practices, underscoring the need to consider the key factors of socioeconomic status, potentially restricted access to fresh food, transportation, and work schedules.

When counseling patients on weight loss and improved nutrition, the authors recommend starting patients with a 2-week food journal of their typical diet.

"Then make small changes such as counseling on reducing, then eliminating, sodas and sugar-sweetened beverages and increasing daily water intake," they suggest.

"Encourage decreasing the frequency of fast food consumption with the ultimate goal of avoidance," they add.

Patients can then be encouraged to gradually change one meal per day for the subsequent month, substituting healthier options based on personal preferences.

Solutions such as baking rather than frying or substituting quinoa or cauliflower rice for white rice can be offered in addition to handouts, recipes, and brands of foods to purchase.

Regularly follow-up with patients, report progress on measures such as weight, and continue to reinforce and encourage them as they develop new tastes and habits, they advise.

"Reassure that over time these improved dietary choices become easier and unhealthy cravings lessen," the authors recommend.  

"But also remind them to allow some pleasurable treats as well and to never punish themselves or feel guilty. A special food upon occasion and in small amounts may be the key to success, as they will not feel deprived or that it is a forbidden fruit," they conclude.

The authors have reported no relevant financial relationships.

Curr Treat Options Gastroenterol. 2019;17:577-586. Abstract

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