I am getting a lot of questions about a headline that was spurred by a recent article published in Cell Metabolism on May 16, 2019 titled: Ultra-Processed Diets Cause Excess Calorie Intake and Weight Gain: An Inpatient Randomized Controlled Trial of Ad Libitum Food Intake.
The highlights of the study were that 20 inpatient adults received either an ultra-processed or an unprocessed diet for 14 days each and then switched diets for another 14 days. The diets were matched for presented calories, sugar, fiber and macronutrient (protein, carbohydrate, and fat) content.
What was found is that when the participants were consuming ultra-processed foods, they on average, consumed approximately 500 additional kcal per day than when they were on the unprocessed food diet. This increase in caloric intake correlated with increases in body weight respectively. In the summary of the article, the authors state that “Limiting consumption of ultra-processed foods may be an effective strategy for obesity prevention and treatment.”
This is a great example of what I will admit is a bias of mine; which is, that a calorie is not just a calorie. Well, in theory it is, and I do believe that energy balance matters, however, our metabolism is far more complex than the age-old “calories in = calories out” equation of weight management. I believe our food (and the quality thereof) provides information to our body and can set off a series of chemical and hormonal responses that can be favorable or unfavorable.
So, what are ultra-processed foods exactly?
For the purposes of this article, The NOVA classification system was utilized.
Ultra-processed foods have been described as ‘‘formulations mostly of cheap industrial sources of dietary energy and nutrients plus additives, using a series of processes’’ and containing minimal whole foods (Monteiro et al., 2018).
It is highlighted that most diets classically focus on the nutrient composition of a diet, however, the NOVA diet classification system hand considers the nature, extent, and purpose of processing when categorizing foods and beverages into four groups:
(1) unprocessed or minimally processed foods (think of food in its most natural form, often, minimal processing includes harvesting, shelling, slaughtering, etc).
(2) processed culinary ingredients (think pressing, drying, milling, grinding, etc).
(3) processed foods (think canning, non-alcoholic fermentation, baking, etc)
(4) ultra-processed foods (think of foods with additives such as dyes, colors, stabilizers, texture enhancers, flavors and preservatives used to imitate or enhance the appeal of foods.
(Monteiro et al., 2018).
These ultra-processed foods are often engineered to make you want more. They are hyper-palatable and usually calorie dense with less water content than unprocessed or minimally processed foods. In the above study, it was noted that the participants ate faster when they were consuming the ultra-processed diet. It is hypothesized that this could be a factor in why they ate more. Can you believe that? These "foods" are actually chemically modified to make you crave them and eat more of them! Doesn't that make you want to boycott them on that basis alone?
The take away for me, and what I teach my patients, is that it is always best to consume most of one’s diet as whole foods. Prepared foods should at least still be identifiable as their whole food form and absent of industrial additives (i.e. it is easy to identify that a homemade tomato sauce is made from crushed tomatoes, herbs and olive oil).
I believe that there is value to having our body “process” the food versus having it done for us. I think we are just starting to learn many of the reasons why this is the case, let alone some of the negatives we are just now learning to many of the industrial additives that were once thought to be “safe.” …Perhaps this could be the topic of another blog post.
Hall et al., Ultra-Processed Diets Cause Excess Calorie Intake and Weight Gain: An Inpatient Randomized ControlledTrial ofAd LibitumFood Intake, Cell Metabolism (2019), https://doi.org/10.1016/j.cmet.2019.05.008
Monteiro CA1, Cannon G2, Moubarac JC2, Levy RB2, Louzada MLC2, Jaime PC1.The UN Decade of Nutrition, the NOVA food classification and the trouble with ultra-processing.Public Health Nutr. 2018 Jan;21(1):5-17. doi: 10.1017/S1368980017000234. Epub 2017 Mar 21.