How Ultra-Processed Foods Could Cause Disease: Calorie Density

Below is an approximation of this video’s audio content. To see any graphs, charts, graphics, images, and quotes to which Dr. Greger may be referring, watch the above video.

One of the mechanisms linking increased consumption of ultra-processed foods and increased risk of death and disease is calorie overload, leading to excess body fat. This could be due to all the extra sugar and fat added to these foods, but in my last video, I profiled a randomized, controlled trial that found that those on the ultra-processed diet gained more weight than those eating unprocessed foods, even when the two diets were matched with the same nutrient profile.

But ultra-processed foods are also designed to be eaten quickly, and indeed, the ultra-processed group snarfed calories at a 50% faster rate. So, changes in texture due to processing may contribute to the calorie overload, but so too may the increased calorie density of ultra-processed foods, as well as the degradation of the food matrix.

Calorie density is the number of calories for a given weight or volume of food. Some foods have more calories per cup, per pound (0.45 kg), per mouthful than others. Oil, for example, has a high calorie density, which means it has a high calorie concentration with lots of calories packed into a small space. Drizzling just one tablespoon of oil on a dish adds 120 calories. For those same 120 calories, you could eat about two cups (300 g) of blackberries, a food with a low calorie density. You could swallow that spoonful of oil and not even feel a difference in your stomach, but eating a couple of cups of berries could start to fill you up.

A handful of jelly beans has about 16 times more calories than a handful of cherry tomatoes. So, for the same number of calories, you could eat that one handful of jelly beans or about four cups (600 g) of cherry tomatoes. A large serving of French fries is about the same size and weight as a baked potato but has about four times as many calories. So, for the same number of calories, you could have that single serving of fries or around four baked potatoes. Which do you think would be more filling?

Ultra-processed foods tend to have twice the calorie density compared to unprocessed foods, more than 1000 calories per pound, similar to what you see at fast food joints, whereas rural West African diets that closely represent the likely diet of our ancient ancestors, average fewer than 500 calories per pound.

So, the biological mechanisms our bodies use to regulate our weight likely evolved in the context of eating at least four or five pounds (1.80 to 2.25 kg) of food a day. That may be the more natural amount of food we eat. If your body is counting on eating five pounds (2.25 kg) of food but you max out with the same number of calories eating just two pounds (1 kg) of ultra-processed food, what do you think happens? It’s no wonder we overeat—our bodies are expecting three more pounds (1.35 kg) of food! Our bodies just weren’t designed to handle such calorie-concentrated diets. No wonder ultra-processed foods are more fattening.

But wait. That study where people ended up four pounds (1.8 kg) heavier within two weeks of eating an ultra-processed diet compared to an unprocessed diet, not only matched the two diets for nutrients like fat and sugar but also for calorie density. How did they do that?

Here’s an example of one of the ultra-processed meals the researchers fed people: a deli meat and cheese quesadilla with ultra-processed refried beans, sour cream, and salsa. Compare that to one of their unprocessed meals: a big Southwestern entrée salad with black beans, nuts, avocados, corn, grapes, apples. Wait a second! How could you possibly make these the same calorie density? The same number of calories per pound? By adding not one, not two, not three, not four, but five cups of Crystal Light—diet, sugar-free lemonade to help even out the calories per total poundage. But that’s kinda cheating. Calorie density shouldn’t be based on foods and beverages, but ideally based on food only, because beverages are so heavy just from the water that they can disproportionately influence calorie density calculations. If you just look at the calorie density of the food, the nonbeverage calorie density was 85% higher on the ultra-processed foods diet, which could account for some of that weight gain.

You can’t fault the researchers for trying the diet lemonade trick; high calorie density is such an inherent property of so many ultra-processed foods. How else could you possibly actually match it with a variety of unprocessed foods? And that’s the problem; high calorie density is one of the reasons ultra-processed foods may be contributing to obesity.

Please consider volunteering to help out on the site.

• Astrup A, Monteiro CA. Does the concept of “ultra-processed foods” help inform dietary guidelines, beyond conventional classification systems? NO. Am J Clin Nutr. 2022;116(6):1482-1488.
• Hall KD, Ayuketah A, Brychta R, et al. Ultra-processed diets cause excess calorie intake and weight gain: an inpatient randomized controlled trial of ad libitum food intake. Cell Metab. 2019;30(1):67-77.e3.
• Hall KD, Ayuketah A, Brychta R, et al. Ultra-processed diets cause excess calorie intake and weight gain: an inpatient randomized controlled trial of ad libitum food intake. Cell Metab. 2019;30(1):67-77.e3.
• Gupta S, Hawk T, Aggarwal A, Drewnowski A. Characterizing ultra-processed foods by energy density, nutrient density, and cost. Front Nutr. 2019;6:70.
• Prentice AM, Jebb SA. Fast foods, energy density and obesity: a possible mechanistic link. Obes Rev. 2003;4(4):187-194.
• Hall KD, Ayuketah A, Brychta R, et al. Ultra-processed diets cause excess calorie intake and weight gain: an inpatient randomized controlled trial of ad libitum food intake. Cell Metab. 2019;30(1):67-77.e3.
• Ledikwe JH, Blanck HM, Khan LK, et al. Dietary energy density determined by eight calculation methods in a nationally representative United States population. J Nutr. 2005;135(2):273-278.
• Forde CG, Mars M, de Graaf K. Ultra-processing or oral processing? A role for energy density and eating rate in moderating energy intake from processed foods. Curr Dev Nutr. 2020;4(3):nzaa019.

Motion graphics by Avo Media

• calories
• cheese
• fat
• junk food
• meat
• obesity
• sugar
• Ultra-Processed Foods
• weight gain