Study under review: Ultra-Processed Diets Cause Excess Calorie Intake and Weight Gain: An Inpatient Randomized Controlled Trial of Ad Libitum Food Intake.
There are dozens of contestants in the fight for the title of “optimal diet”: vegetarian, vegan, paleo, keto … and the list goes on. The question of what diet is “best” is far from settled—and it’s quite possible that there’s no such thing as a single “best” diet for everyone. Focusing on which diets are “best” makes it very easy to overlook an important point: almost all of these diets agree that ultra-processed foods should be avoided.
Ultra-processed foods are mixtures of specific parts of different foods, generally constituents that have undergone multiple processing steps after harvesting and are subsequently low in fiber, protein, and various micronutrients, and high in added fats, sugars, or salt. These foods have been described not as foods at all, but as—“formulation(s) mostly of cheap industrial sources of dietary energy and nutrients plus additives …” Doesn’t sound too appealing when phrased that way, does it?
Yet, as shown in Figure 1, the sales of ultra-processed foods have been inching upward from 2002-2016 in all major regions of the world except North America, Australasia, and Western Europe. Sales may have stagnated in the latter three regions, but they also exhibit the highest sales of ultra-processed food, by volume, in the world. After all, the purpose of ultra-processing is to create convenient and highly palatable food products from low-cost ingredients.Their convenience, taste, and generally low cost can be quite alluring.
But, convenient, tasty food may have a downside. Increases in sales of ultra-processed foods are positively associated with population-level BMI trajectories. In fact, ultra-processed food consumption has been associated with higher risk of overweight and obesity, hypertension, cancer, and even mortality in prospective studies. These foods have been associated with addictive-like eating behaviors and have been suggested to facilitate overeating. The problem is that these studies only establish a predictive correlation, not causation.
Since no causal relationship between ultra-processed food intake and obesity or excess energy intake has been established, researchers from the National Institute of Diabetes and Digestive and Kidney Diseases in Bethesda, Maryland conducted a randomized controlled trial comparing ad libitum energy intake on diets based primarily on ultra-processed compared to unprocessed foods.
Ultra-processed foods are food products that have undergone multiple processing steps after harvesting. They are often designed for convenience, palatability, and low cost. However, these foods have been linked to overeating and the ever-increasing global burden of noncommunicable diseases. To determine whether there might be a causal relationship between ultra-processed foods and energy intake, the researchers of the study under review conducted a randomized controlled trial comparing ad libitum energy intake during an ultra-processed diet, compared to a minimally processed diet.
Other Articles in Issue #57 (July 2019)
Good meat, bad meat, red meat, white meat
Red meat is linked to poor heart health in observational studies, but recent evidence suggests that this correlation isn't causal. Part of the story may come down to saturated fat content. This trial puts that theory to the test.
Can HMB help maintain muscle in people at risk for muscle loss?
People with serious diseases can lose muscle mass, which impacts their quality of life. This meta-analysis examined whether HMB can help people with illnesses keep some of their muscle mass.
Mini: Mo’ ingredients, mo’ problems
Multi-ingredient pre-workout supplements may be convenient, but they also have their downsides.
More guacamole, fewer chips: evaluating avocados and hunger
Different nutrients have different impacts on hunger. This study explored whether swapping carbs for avocado can impact measures of satiety.
Mini: The American Diabetes Association’s consensus report on nutrition therapy for adults with diabetes and prediabetes
We cover some key takeaways from this recent update of the 2014 ADA consensus report.
Pumped up!? Can citrulline really improve athletic performance?
Citrulline is a non-essential amino acid that could boost performance in theory. But does it do so in fact? Here, we review a recent meta-analysis examining this question.
Beyond connective tissue: investigating collagen supplementation for strength and muscle mass
Getting enough protein is an essential part of gaining muscle mass. However, not all protein's created equal. This RCT aimed to explore whether collagen supplementation can help bulk up.