Want to Maximize Weight Loss? Look to Less Processing, Not Just Fewer Calories

A recent study shows that people who ate minimally processed foods lost about twice as much weight as those eating ultra-processed foods. That could mean food quality is just as important to post-bariatric life as calories.

People are used to focusing on calories, portion sizes, protein intake, or finding the “right” diet plan. But there’s possibly another factor to consider: the quality of the food you’re eating.

Ultra-processed foods are common in today’s food environment because they are convenient, affordable, and accessible. What are they? Packaged foods that have been significantly altered from their original form and often contain additives or ingredients not typically used in home cooking. On the flip side of that are minimally processed foods: fruits, vegetables, eggs, lean meats, dairy products, beans, and whole grains.

In a recent study, researchers examined whether the level of food processing itself could influence weight loss. Two diets were compared, ultra-processed versus minimally processed, but each diet was specifically selected to meet nutritional recommendations. Despite the effort to make both diets “healthy,” participants who ate minimally processed foods lost more weight. This could turn out to be a game changer for those struggling with obesity.¹

Why Would Food Processing Matter for Weight Management?

The study included 55 obese adults who followed two different diets for eight weeks each. The important distinction was that researchers weren’t comparing a “healthy” diet to an “unhealthy” one. Both eating plans met recommendations for nutrients, fruits and vegetables, fiber, and other markers of a balanced diet. The primary difference was how much the foods had been processed before they reached the plate.

Participants also lost weight on both diets. However, the minimally processed group lost about twice as much. Not only that, but they also had greater reductions in body mass index (BMI) and body fat. Why would that matter, especially if nutritional recommendations were met in both groups?

Researchers came up with several ideas. Minimally processed foods tend to provide fewer calories for the same volume of food and generally take longer to chew and eat. Slowed eating gives the body’s natural fullness signals more time to work, which could help explain why participants consumed fewer calories. They also reported better craving control on the minimally processed diet.

Ultra-processed foods are designed to be convenient, highly palatable, and ready to eat with little preparation. There’s nothing inherently wrong with that, especially when it’s an occasional treat, but they’re easy to eat quickly, making it more difficult to recognize when you’re satisfied. Eating a diet full of ultra-processed foods requires consciously restricting portions, whereas minimally processed foods naturally encourage slower eating, early satiation, and, potentially, portion restriction.

Another interesting aspect was that the ultra-processed food items were low in saturated fat, sugar, and sodium and included recommended amounts of fiber, fruits, and vegetables. Even so, participants still lost more weight eating minimally processed foods. It suggests that the nutritional content, combined with the degree of processing, influences how our bodies respond to food.

For people living with obesity, this is an important reminder that the foods available in our environment can influence hunger, cravings, eating speed, and overall calorie intake. Gradually choosing more minimally processed options might be one practical way to bolster the success of long-term weight loss, including after bariatric surgery.

How to Apply This to Your Weight Loss Journey

You don’t have to overhaul your entire diet overnight. Just start making moves toward small, sustainable changes. When possible, prepare meals at home so you have greater control over the ingredients and lean into proteins, vegetables, fruits, beans, whole grains, eggs, and low-fat dairy. As far as protein goes, aim for chicken thighs rather than chicken sausage or a pork chop as opposed to ground pork patties. The closer food is to its natural state, the less processed it is.

For people thinking about bariatric surgery or adjusting to life after surgery, better eating habits are even more important. Protein intake, nutrient density, and portion control are foundational to long-term success, and, based on this study, choosing minimally processed foods could elevate your effort, improve fullness, reduce cravings, and make it easier to maintain healthy eating patterns. Rather than focusing only on calories, pay attention to the quality of those calories.

At SAMPA, we want to help patients develop strategies for nutrition, weight management, and lasting lifestyle changes. Whether you need additional support after surgery or have questions leading up to a procedure, our team is here to help you understand your options.

Reference:

1. Dicken, S. J., Jassil, F. C., Brown, A., Kalis, M., Stanley, C., Ranson, C., Ruwona, T., Qamar, S., Buck, C., Mallik, R., Hamid, N., Bird, J. M., Brown, A., Norton, B., Gandini Wheeler-Kingshott, C. A. M., Hamer, M., van Tulleken, C., Hall, K. D., Fisher, A., … Batterham, R. L. (2025). Ultraprocessed or minimally processed diets following healthy dietary guidelines on weight and cardiometabolic health: A randomized, crossover trial. Nature Medicine, 31. https://doi.org/10.1038/s41591-025-03842-0.