When it comes to weight loss and nutrition, how many calories you consume and how much you exercise are two obvious factors to watch. But while a doughnut and several cups of fresh pineapple are roughly 200 calories, not all calories are created equal. There are other important factors to consider beyond calories and macros — where the food comes from, how it’s processed and what’s added to it. The National Institutes of Health recently published a new study that explores the topic.
Here, what you need to know about the study, other research on the topic and how you can use this information to help improve your own health and diet:
THE LATEST RESEARCH
Researchers developed a food classification system that separated foods into four categories based on the extent to which they were processed:
- Unprocessed or minimally processed fruits, vegetables, beans, whole grains, eggs, meats
- Processed culinary ingredients (i.e., oils, butter, salt)
- Processed foods (i.e., canned foods, bread and cured meat)
- Ultra-processed foods (i.e., sweet or savory snacks, ready-to-eat packaged foods, snack bars, poultry and fish nuggets). Ultra-processed foods are designed for mass consumption, hyper-palatability, and high profitability by adding salt, sugar, oil and/or preservatives to extend shelf life and increase ease of consumption. On the other hand, unprocessed foods do not add salt, sugar or fat and only undergo minimal processing to make them safe to eat.
The study participants spent two weeks eating as much as they wanted from an ultra-processed food diet and then another two weeks eating an unprocessed diet (where they had every meal prepared for them).
Researchers found people ate more of the processed meals, to the tune of roughly 500 calories per day, even though the processed and unprocessed meals had the same amount of calories, protein, carbohydrates, fat, fiber and sodium. The results show when you eat processed foods and watch your portion sizes, you’ll still feel less full and want to eat more than if you ate more filling, unprocessed foods.
UNPROCESSED VERSUS PROCESSED FOODS
Fiber and protein found more commonly in unprocessed foods should make you feel full longer, and sodium in processed foods generally makes you want to eat more of that particular food. However, this study found even when those factors are matched, the subjects ate more calories on an ultra-processed food diet.
Still, the study didn’t explore why people ate more on the ultra-processed food diet. They found participants enjoyed each of the meals equally, so this was not a case of “healthy food tastes bad so I’m not going to eat it.” Interestingly, researchers found participants ate ultra-processed foods faster (eating 10 calories more per minute) compared to unprocessed foods.
They also found that while both meals had the same amount of fat and carbs, subjects consumed more fat and carbs on the ultra-processed diet (most of which occurred at breakfast and lunch), while eating the same amount of protein as the unprocessed diet.
WHAT ABOUT PREVIOUS RESEARCH?
Previous research shows ultra-processed foods tend to be lower in protein and fiber, and those nutrients make you feel full sooner and for longer. Differences in calorie intake were thought to be due to the lack of protein and fiber in the ultra-processed foods, but this new study throws a wrench in that hypothesis since fiber and protein were the same, while fat and carbs were higher in the ultra-processed diet.
One potential reason could be that in this new study, the source of fiber in the ultra-processed diet was not from the food itself. Instead, fiber supplements were added to the beverages because the food was not rich enough in fiber to match the unprocessed diet. Fiber supplements in drinks don’t influence satiety the way fiber in food does, which may have contributed, at least in part, to the overconsumption of calories.
Another piece of the puzzle comes from previous research on the “protein leverage” theory. Humans unconsciously try to eat enough protein to sustain their bodies. If they aren’t getting enough protein, they might increase the amount of calories they eat overall in an attempt to get more protein. Since less protein was consumed earlier in the day, participants may have overeaten later without realizing it was their body’s way of signaling it needed more protein.
Ultra-processed foods like diet soda are often high in artificial sweeteners, resulting in misleading hunger signals. The tongue tastes the soda’s sweetness and expects calories, so the body reacts by releasing enzymes to digest calories. When it doesn’t get them, it makes you hungry, thus you’re more likely to overeat.
THE BOTTOM LINE
No matter where you fall with your eating strategies, this new study shows the quality of calories matter, especially when you’re eating to lose weight. If you’re trying to reduce your overall food intake, you’ll want to optimize the calories you’re eating so you feel full every day. It’s possible eating less might be easier if you stick to whole, unprocessed foods and eat more protein earlier in the day. It’ll be easier to build and sustain healthy habits because your hunger will be more satisfied with your meals.
It’s also important to be mindful of the speed at which you eat. This study illustrates that when you eat faster, you eat more and it’s easier to do so when eating ultra-processed foods. For best results, slow down and enjoy your food without distractions.
Ultimately, while calorie counting and specific macro breakdowns can be helpful in gauging what your body needs, focus on eating whole foods and throw in ultra-processed foods as an exception to your habit.
Poti, J.M., Mendez, M.A., Ng, S.W., and Popkin, B.M. (2015). Is the degree of food processing and convenience linked with the nutritional quality of foods purchased by US households? Am J Clin Nutr 101, 1251-1262
Poti, J.M., Braga, B., and Qin, B. (2017). Ultra-processed Food Intake and Obesity: What Really Matters for Health-Processing or Nutrient Content? Current obesity reports 6, 420-431.
Martinez Steele, E., Raubenheimer, D., Simpson, S.J., Baraldi, L.G., and Monteiro, C.A. (2018). Ultra-processed foods, protein leverage and energy intake in the USA. Public Health Nutr 21, 114-124.