Your Body on Ultra-Processed Foods: Weight Gain, Muscle Loss, and Stubborn Fat

How do ultra-processed foods affect your body?

Ultraprocessed foods are foods that undergo complex manufacturing processes and contain artificial ingredients, such as preservatives, artificial flavors, and stabilizers. These foods include fast food, soft drinks, processed sweets, and ready-made meals. Although they are delicious and simple to prepare, studies suggest that they may be harmful to our health in the long run.

What happens when we eat ultra-processed foods?

Researcher Kevin Hall, a metabolic specialist, conducted a study to find out how these foods affect the body. In this study, participants were admitted to a medical laboratory for a month, where they were given four different diets:

An unprocessed diet: based on natural foods such as fresh vegetables, legumes, and whole grains.

Three ultra-processed diets: containing the same amount of essential nutrients (such as sugar, fat, protein, and fiber) but highly processed.

The results were interesting:

When participants ate unprocessed foods, they consumed about 2,700 fewer calories per day and lost about half a kilogram of fat.

But when they switched to a diet that was 80% ultra-processed, their daily calorie intake increased to 3,700 calories, resulting in an increase of more than a kilogram in just one week!

Why do we eat more when we consume ultra-processed foods?

There are several reasons why we eat more when we eat these foods:

High calorie density: Ultra-processed foods contain more calories per bite than fresh foods.

Dilute quickly: These foods digest feverishly, leaving us hungry again shortly after.

Food addiction: Some ultra-processed foods are designed to be “hyper-palatable,” combining sugar, salt, and fat in ways that make us want to eat more of them.

Can ultra-processed foods be made less harmful?

Although eliminating these foods completely can be difficult, there are some tweaks that can reduce their negative effects. In the study, researchers tried two new diets:

Cutting down on ultra-processed foods: foods that combine sugar, salt, and fat in unnatural ways were cut. However, they found that this change reduced intake by only 200 calories per day and was not enough to prevent weight gain.

Adding water-rich foods: non-starchy vegetables (like lettuce or broccoli). These foods add volume to meals with few calories, helping you feel full without gaining weight.

When non-starchy vegetables were added to the ultra-processed diet, participants lost about a pound in a week while reducing their daily calorie intake by about 830 calories.

The big challenge: Losing fat without losing muscle

Although the modified diet helped reduce weight, the weight loss was due to lean mass (such as muscle or water), not fat. This suggests that ultra-processed foods may affect how the body digests nourishment and distributes nutrients.

“If we can understand the mechanisms behind these effects, scientists and nutritionists can re-engineer some of these foods to make them healthier,” says Kevin Hall.

Practical tips to improve your diet

While waiting for more research, here are some simple tips to help reduce the negative effects of ultra-processed foods:

Add vegetables to your meals, whether fresh or frozen, such as salads, broccoli, or carrots.

Try legumes, such as beans or legume-rich soups.

Choose whole grains, such as oats, brown rice, or quinoa.

Reduce added sugars: Pay attention to the amount of sugar in yogurt, granola, or sauces.

Focus on filling, nutritious foods, such as eggs, even if they’re the processed kind.

The bottom line

Ultra-processed foods may be an integral part of our daily lives, but a few simple tweaks can help reduce their negative effects. By adding vegetables and cutting back on tempting foods, we can improve the quality of our meals without completely abandoning processed foods. As research continues, we may discover new ways to redesign these foods to make them more suitable for our health.