Last week I explored why we blame the fat person for being fat. I concluded that we need to be sensitive to the feelings of fat people. We should not shame them. They deserve the same respect as anyone else. This week we blame the food—processed food. I shift to the more technical term obesity when addressing processed food. Processed food is making America obese, or so we hear. Is this concept valid? If we removed all processed food from the American diet, would we become a fat-free society?

Avoid processed foods is the battle cry of food activists. Critics claim that processed foods are junk foods. Filled with sugar and fat, they contribute only empty calories. Junk food is too tempting and leads to overeating. Overeating leads to weight accumulation. Weight accumulation leads to obesity. Some critics claim processed foods are addictive. Marketing feeds these addictions. Americans don’t stand a chance. It is a wonder that all Americans aren’t obese. The most eloquent critic of processed foods is Michael Pollan who published Food Rules.

Food Rule#6: “Avoid foods that contain more than five ingredients.”

Carlos Monteiro classified foods into four NOVA groups. We should avoid ultra-processed foods at all costs. These are foods with additives. One food process forbidden is extrusion. NOVA considers pasta as unprocessed even though it’s extruded. Canned and frozen foods with five ingredients or less are minimally processed and OK to eat. Sugar is not a processed food but a culinary ingredient. It is safe to use in home baking but harmful when added by food companies.  

Big Food deflects responsibility for the obesity epidemic. With the onset of COVID-19, we no longer hear about an obesity pandemic. Big Food tells us that a calorie a calorie. It produces high-calorie foods, but it also manufactures low-calorie products. The industry blames the increase on obesity to a decrease in exercise. Consumers prefer the high-calorie foods to low calorie alternatives. The food industry sells nutritious foods and not so nutritious foods. Critics deplore the low nutrient energy dense foods (LNED), products like Twinkies (1). Big Food also features HNED foods like premium chocolate milk. We can find LNEL (low nutrition energy light) items such as diet soda. Slim Fast is a HNEL food. Do only LNED and HNED foods contribute to obesity? Big Food claims that it just produces what consumers want. It gives people choices. Isn’t that what the American economy is all about?

Are processed foods responsible for obesity? As I did last week, I dipped into the scientific literature to answer this question. Once again, it is not a comprehensive look. I found surveys of populations in Australia (2) and the United Kingdom (3). I also found four reviews of the effects of processed foods on obesity (4-7). The focus of all these articles was on ultra-processed foods as defined by NOVA. Processing as such is not the problem. One article noted that ultra-processed differed from processed in “industrial formulation.” That means that it is the addition of food additives and not the process (2) converts a processed food to an ultra-processed one. All six articles concluded that consumption of ultra-processed foods leads to obesity. A 10% increase in consumption of ultra-processed foods led to an 18% increase in obesity (2,3). The trend is worldwide.

NOVA is not consistent in its definition of ultra-processed foods (5). The definition changes over time. Coding of what constitutes an ultra-processed food differs from study to study. One survey added alternative meats to the list (3). Most articles identified ultra-processed foods as high in sugar and fat and low in fiber (2-4,6) or LNEDs. A review uncovered no association of these products with “beneficial health outcomes” (5). I read only one article that separated out subcategories of this vast group of products (6). Consumption of soft drinks and sugar-sweetened beverages increased body fat. Consumption of chocolate products and ready-to-eat breakfast cereals decreased body fat. Looking at details, I noted that smokers ate more ultra-processed foods but were not as obese as nonsmokers (3).

One article reviewed dietary intervention studies of obese subjects (8). Consumption of ultra-processed foods led to decreased healthy microbes in some studies. A healthy microbiome appears to protect against obesity. Results in the studies reviewed were inconsistent, making firm conclusions difficult. One review speculated on some possible explanations for the relationship between processed foods and obesity (4). They provided two explanations—consuming acrylamide and overeating. Acrylamide forms during heating at high temperatures, such as baking, frying, and roasting. The chemical forms in both commercial operations and home cooking. Overeating makes sense as weight increased with energy intake (3-5). The more calories we consume the fatter we get. People eating ultra-processed foods are more likely to overeat. Nothing earth-shattering here. There are no biochemical mechanisms proposed beyond calorie consumption.  

So, can we blame processed foods for making us fat? Not so fast. Correlation does not prove causation. The data show a very strong correlation between ultra-processed food and obesity. It is probable that eating too many ultra-processed foods leads to weight gain. Weight gain increases our chances of becoming obese. In the 1970s Flip Wilson had an answer for all his sins, “The devil made me do it.” Are ultra-processed foods the obesity devil? They might be if processed food is addictive. More on food addiction in July on this site. They could be if obesity is pre-programmed in children by the age of five. They may be if the Set Point Theory is real (9).

The NOVA definition of ultra-processed foods found in the references is too expansive. It includes junk foods (LNEDs). It also includes HNEDs, LNELs, and HNELs. It is time that researchers subdivided ultra-processed foods into subcategories. It requires careful coding (6). Otherwise, a bowl of Fiber One is as dangerous to us as a Twinkie. Without a biochemical mechanism, all we can conclude is that overeating ultra-processed foods makes us fat. Then again overeating any combination of foods leads to obesity.

NOVA considers these ultra-processed foods to be equally dangerous

Some caveats here. I had modest success in obtaining grants during my research career. I also served on grant panels. First, studies on ultra-processed foods are not neutral. Governmental agencies funded most of the articles cited in the references at the end of this post. The operating paradigm presupposes that ultra-processed foods are a threat to human health. If a grant proposal fails to hypothesize an adverse effect, it will not receive funds. The agency will want preliminary data showing the effects. If manuscripts written on these data do not demonstrate negative relationships, a prestigious journal will not accept it. This situation does not mean the researchers are unethical. Natural selection takes its course. Those researchers with conclusive data rise to the top of the food chain.

Observational and correlative studies have fewer restrictions than experimental studies. They also do not carry as much prestige. I could not receive grant funding from federal agencies without a plausible, biochemical mechanism. Ultra-processed studies will not remain credible until a plausible, biochemical mechanism is established. Without a mechanism there are no good calories or bad calories. Only calories. Ultra-processed calories may attract us, causing us to overeat. It still is about calories consumed and calories absorbed. The only mechanism I see on the horizon is with the microbiome (8). As Linn Steward suggests, the food matrix may prevent calories from absorption.* To this point, research has indicted but not convicted these foods.

If we removed all processed food from the American diet, would we become a fat-free society? We will never be a fat-free society, but we could reduce the level of obesity with a better understanding of the cause. Articles referenced in this post point to ultra-processed foods as the culprit. If so, are they all to blame or only a subset of the category?* These products make up from 23% of the Malaysian diet up to 56% of the American diet (5). Future research must establish a mechanism. It must also isolate the food(s) or ingredient(s) responsible for rising rates of obesity. Until then we won’t know who or what to blame.

Next week: Blaming American culture for the rise in obesity around the world

*See comments to last week’s post

References:

(1) de La Haye, K., G. Robbins, P. Mohr, and C. Wilson, 2013. Adolescents’ intake of junk food: Processes and mechanisms driving consumption similarities among friends. Journal of Research on Adolescence 23(3):524-536. doi:10.1111/jora.12045    

(2) Machado, P.P., E. Martinez Steele, R.B. Levy, M.L. Costa Louzada, A. Rangan, J. Woods, T. Gill, G. Scrinis, and C.A. Monteiro, 2020. Ultra-processed food consumption and obesity in the Australian adult population. Nutrition and Diabetes 10: 39. http://doi.org/10.1038/s41387-020-00141-0    

(3) Rauber, F., E. Martinez Steele, M.L. Costa Louzada, C. Millett, C.A. Monteiro, and R.B. Levy, 2020.  Ultra-processed food consumption and indicators of obesity in the United Kingdom population (2008-2016). PLoS One 15(5):e0232676. http://doi.org/10.1371/journal.pone.0232676

(4) Pagliai, G., M. Dinu, M.P. Madarena, M. Bonaccio, L. Iacoviello, and F. Sofa, 2021. Consumption of ultra-processed foods and health status: a systematic review and meta-analysis. British Journal of Nutrition 125:308-318. doi:10.1017/S0007114520002688  

(5) Elizabeth, L., P. Machado, M. Zinocker, P. Baker and M. Lawrence, 2020. Ultra-processed foods and health outcomes: A narrative review. Nutrients 12:1955. doi:10.3390/nu12071955  

(6) Costa, C.S., B. Del-Ponte, M.C. F. Assuncao, and I.S. Santos, 2017. Consumption of ultra-processed foods and body fat during childhood and adolescence: A systematic review. Public Health Nutrition 21(1): 148-159. doi.10.1017/S1368980017001331 

(7) Costa de Miranda, R., F. Rauber, and R.B. Levy. 2021. Impact of ultra-processed food consumption on metabolic health. Current Opinion Lipidology 32::24-37. doi:10.1097/MOL.0000000000000728   

(8) Lane, M., G. Howland, M. West, M. Hockey, W. Marx, A. Loughman, M. O’Hely, F. Jacka, and T. Rocks, 2020. The effect of ultra-processed very low-energy diets on gut microbiota and metabolic outcomes in individuals with obesity: A systematic literature review. Obesity Research & Clinical Practice 14:197-204. https://doi.org/10.1016/j.orcp.2020.04.006 

(9) Farias, M.M., A.M. Cuevas, and F. Rodriguez, 2011. Set-point theory and obesity. Metabolic Syndrome and Related Disorders 9(2):85. dx.doi.org/10.1089/met2010.0090