How Processed Foods are Highly Correlated with ObesityDecember 1, 2021
It comes as no surprise that the consumption of processed foods such as chips, candy bars, and the like are correlated with weight gain and obesity. (https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7399967/)
These foods lack nutritional value and pack the calories, leading one to feel unsatisfied and often craving more. But are there other factors involved besides just a lack of nutrition?
How Processed Foods are Highly Correlated with Obesity
Some researchers are discovering links specifically between a lack of fiber in one’s diet and an increase in the consumption of processed foods. Fiber helps to promote satiety by decreasing the transit time and drawing more water to the intestines allowing one to feel more full; plus, it aids in the growth of beneficial bacteria in the large intestines.
However, with the introduction and use of emulsifiers in processed foods, researchers have been examining the ways in which they may influence the microbiota (or variety of bacteria) in our gut, among other metabolic changes.
Since emulsifiers work to blend water and fat, the purpose of emulsifiers is to increase shelf-life and prevent the separation of fat in foods. Food companies also use emulsifiers to improve taste and texture. “Some of the most commonly used emulsifiers include carboxymethylcellulose (CMC), polysorbate-80 (P80), arabinogalactan, carrageenan, and gum Arabic.” (https://link.springer.com/article/10.1007%2Fs11894-019-0723-4)
While the use of emulsifiers has been granted GRAS (Generally Recognized As Safe) status, the process by which many foods have been able to use emulsifiers is much higher than was initially intended.
The FAO and WHO expert committees met in 1955 to discuss the safety of food additives. They initially decided that up to 1% of additives was considered GRAS. However, because the process to evaluate the safety of food additives can be very long, and the FDA has allowed food companies to submit their own analyses of foods, the number of additives in food is likely much higher than was originally intended for GRAS status.
Additional effects that may stem from that alteration of the gut microbiota and the consumption of processed foods could then lead to an increase in blood glucose levels, an increase in hunger, and ultimately an increase in adiposity and weight gain. (https://pubmed.ncbi.nlm.nih.gov/31786723/)
The ways in which processed foods contribute to alterations in the microbiota include the lack of diversity of “good” bacteria and thus a subsequent overgrowth of “bad” bacteria.
Emulsifiers specifically have been shown to reduce mucin levels (which is the protective layer) of the intestinal lining. This can lead to increased intestinal permeability – when the tight junctions of the intestines open to allow larger proteins and molecules to pass through that were not originally intended to pass through the gut lining. When the body doesn’t recognize these “foreign” particles, it starts to attack them, leading to an increase in inflammation. (https://link.springer.com/article/10.1007%2Fs11894-019-0723-4 )
This increase in inflammation has also been thought to increase insulin levels, which will subsequently lower blood glucose levels, leading to an increase in hunger – often for carbohydrate-containing foods. This further drives the cycle of higher blood glucose leading to a further increase in insulin levels. Higher insulin levels also stimulate the storage of fat in the body which ultimately leads to weight gain over time.
Processed Foods and Obesity
The other factors that can be at play include the rate at which one is able to eat processed foods. Since processed foods lack fiber, there is much less chewing involved, which leads to faster consumption of these foods without the corresponding feelings of fullness.
The conversion of processed carbohydrates into sugar happens almost instantaneously. It’s almost as if many of those foods (like chips, crackers, and candy) practically melt in your mouth.
The fact that they are full of fat, sugar, and salt may also stimulate the pleasure centers of the brain and elicit a dopamine response. This is the reason we continue to crave them even though we know they aren’t healthy options. They don’t promote satiety, so over-consumption is easy.
Much research has examined the concept of “addiction” to food in similar ways a person would be addicted to drugs through the dopamine response system (https://www.nature.com/articles/nrn.2017.130/boxes/bx1).
The problem is that individuals often derive so much more pleasure from eating foods with added fat, sugar, and salt, whereas the same pleasure does not come from whole, unprocessed foods.
In fact, the addition of fiber and protein to one’s diet promotes more feelings of fullness and thus a greater satisfaction after eating; individuals are usually not left wanting more. Much research has indicated that the higher liking for fat (and often sugar and salt among certain groups of individuals) is linked to an increase in body weight (https://ijbnpa.biomedcentral.com/articles/10.1186/s12966-016-0406-6).
Therefore, making healthier food choices leads to weight loss not only because of the decrease in overall calories and increase in nutrients, but also because of the gut, metabolic, and satiety effects of these foods.
ABOUT THE AUTHORMichelle Bauche, MS, RDN, LD, CSOWM is a registered dietitian working for Missouri Bariatric Services in Columbia, Missouri. She is a certified specialist in Obesity and Weight Management and a member of the Weight Management Dietetic Practice Group through the Academy of Nutrition and Dietetics. Read more articles by Michelle!