The Skeptical Cardiologist has been ranting about the deleterious effects of added sugars from highly-processed food in our diets ad nauseam (see here or here).
Two recent discussions further support the role ultra-processed foods (UPFs) play in our obesity epidemic.
The Guardian published a long article that provides an easily digested background to the concept of UPFs and their influence on obesity. A lot of that background comes from the work of Carlos Monteiro, MD, from Brazil:
“The concept of UPFs was born in the early years of this millennium when a Brazilian scientist called Carlos Monteiro noticed a paradox. People appeared to be buying less sugar, yet obesity and type 2 diabetes were going up. A team of Brazilian nutrition researchers led by Monteiro, based at the university of Sao Paulo, had been tracking the nation’s diet since the 80s, asking households to record the foods they bought. One of the biggest trends to jump out of the data was that, while the amount of sugar and oil people were buying was going down, their sugar consumption was vastly increasing, because of all of the ready-to-eat sugary products that were now available, from packaged cakes to chocolate breakfast cereal, that were easy to eat in large quantities without thinking about it.”
I highly recommend you read the full article in The Guardian on this important topic. It is extremely well-written and the author has interviewed both Monteiro and Kevin Hall for the piece.
I’ve been meaning to follow up on some recent evidence showing the major role that the sugar industry played in vilifying fat and obscuring the dangers of excess sugar in the diet.
Here are two items to help you further understand this process:
A researcher at the University of California San Francisco uncovered documents showing that Big Sugar paid three Harvard scientists in the 1960s to play down the connection between sugar and heart disease and instead point the finger at saturated fat. Coca-Cola and candy makers made similar headlines for their forays into nutrition science, funding studies that discounted the link between sugar and obesity.
An observational study by Monteiro, et al. in BMJ Open confirmed the presumed close association between highly processed foods and added sugar and added further to the evidence that sugar, not fat, is the major nutrient which most of us should minimize in our diet.
‘Empty Calories’
Monteiro and his colleagues began that paper by noting that dietary guidelines are increasingly recommending limiting added sugar to <10% of dietary calories because of evidence that “a high intake of added sugars increases the risk of weight gain, excess body weight, and obesity; type 2 diabetes mellitus, higher serum triglycerides and high blood cholesterol; higher blood pressure and hypertension; stroke; coronary heart disease; cancer; and dental caries.”
“Moreover, foods higher in added sugars are often a source of empty calories with minimum essential nutrients or dietary fibre which displace more nutrient-dense foods and lead, in turn, to simultaneously overfed and undernourished individuals.”
The study analyzed the relationship between processed food consumption, total calories, and calories from added sugar using data from the National Health and Nutrition Examination Survey 2009-2010.
They divided foods into four categories:
- Unprocessed or minimally processed foods: Fresh, dry, or frozen fruits or vegetables, grains, legumes, meat, fish, and milk
- Processed culinary ingredients: Table sugar, oils, fats, salt, and other substances extracted from foods or from nature and used in kitchens to make culinary preparations
- Processed foods: Foods manufactured with the addition of salt, sugar, or other substances of culinary use to unprocessed or minimally-processed foods, such as canned food, simple breads, and cheese
- Ultra-processed foods: Formulations of several ingredients that — besides salt, sugar, oils, and fats — include food substances not used in culinary preparations, in particular, flavors, colors, sweeteners, emulsifiers, and other additives used to imitate sensory qualities of unprocessed or minimally-processed foods and their culinary preparations or to disguise undesirable qualities of the final product
The top ultra-processed foods by calorie intake were breads, beverages, cakes, cookies and pies, salty snacks, frozen and shelf-stable dishes, pizza, and breakfast cereals.
Altogether, ultra-processed foods accounted for 58% of all calories in the U.S. diet and nearly 90% of all added sugars.
Kevin Hall’s Stunning Study
The second item about UPFs was an episode of the keto diet company Key Eats’ podcast Best Known Method with Ethan Weiss, MD, interviewing the National Institute of Diabetes and Digestive and Kidney Diseases nutrition researcher Kevin Hall discussing ultra-processed foods.
The early part of the podcast reviews Hall’s early training in physics and mathematics and transitions into mathematical modeling of metabolism. Ultimately, he ended up testing the hypothesis that a diet of UPF with similar macronutrient composition would result in greater weight gain than an unprocessed diet.
The results were published in Cell Metabolism last year and are summarized in this neat graphic.
Yes. You read that correctly.
Among 20 inpatient adults (10 men and 10 women), the ultra-processed diet caused increased ad libitum energy intake and weight gain despite being matched to the unprocessed diet for presented calories, sugar, fat, sodium, fiber, and macronutrients.
Hall said he expected negative results from this study but now believes something about UPFs beyond their macronutrient composition causes many individuals to overeat and gain weight. Whereas in 2016, I thought the major culprit was the added sugar in UPFs, Hall’s study suggested it is not just added sugar or missing fiber in the diet that is leading to excess eating and weight gain.
Identifying Ultra-Processed Foods
If you have difficulty in determining what foods should be considered ultra-processed I recommend getting a copy of Michael Pollan’s small and delightful booklet, “Food Rules: An Eater’s Manual.”
The first section entitled “Eat Food” provides 21 short, memorable phrases to help you identify and avoid ultra-processed foods, concoctions that he terms “edible food-like substances.”
Some of the key rules:
- Don’t eat anything your grandmother wouldn’t recognize as food
- Avoid food products with ingredients that no ordinary human would keep in the pantry
- Avoid things that contain high fructose corn syrup
- Avoid foods that have some form of sugar (or sweetener) listed among the top three ingredients
- Avoid food products that contain more than five ingredients
- Avoid food products with the wordoid “lite” or the terms “low-fat” or “nonfat” in them (one I particularly like as it emphasizes the misleading health claims of low-fat diary)
As previously indicated in the post “I Am a Keto-friendly cardiologist and I Love Keyto,” I have tremendous professional respect for Weiss, the cardiologist behind Keyto (now Key Eats). It is ironic that Key Eats’ first products are (seemingly) ultra-processed food bars.
Anthony Pearson, MD, is a private practice noninvasive cardiologist and medical director of echocardiography at St. Luke’s Hospital in St. Louis. He blogs on nutrition, cardiac testing, quackery, and other things worthy of skepticism at The Skeptical Cardiologist, where a version of this post first appeared.