Francesca Biagioli A new study looked at how a vegan diet and processed food consumption affect weight loss, showing surprising results
In recent years, plant-based diets have surged in popularity—not only for their environmental benefits but also for their positive effects on health, especially when it comes to weight loss. But here’s a key detail many overlook: not all vegan foods support weight loss equally.
A recent study published in Nutrition and Metabolism sheds light on this issue. Led by Dr. Priyom Bose, the research team explored how the level of food processing impacts weight loss in people following a vegan diet.
The real key to weight loss is limiting processed foods—whether plant-based or not”
The study involved 244 overweight adults (BMI between 28 and 40), aged 25 to 75. Participants were randomly assigned to two groups: one followed a vegan diet, while the other stuck to their regular eating habits.
To evaluate the types of food consumed, researchers used the NOVA classification system, which breaks food down into four categories:
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Unprocessed or minimally processed foods (fresh fruits, vegetables, whole grains)
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Processed culinary ingredients (sugar, salt, oils)
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Processed foods (like bread and cheese, with added preservatives or sugars)
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Ultra-processed foods (packaged snacks, ready meals, sugary drinks)
Participants recorded what they ate, and researchers tracked their weight at the beginning and after 16 weeks. The goal? To see how plant-based and animal-based foods, with different levels of processing, impacted weight differently.
Reducing 1.8 oz of processed animal foods a day helped participants lose 2.2 lbs”
The results were surprising.
The most striking finding was that cutting back on processed animal-based foods had a significant impact on weight loss. Specifically, reducing intake by 1.8 ounces (50 grams) per day was linked to losing roughly 2.2 pounds (1 kg).
But here’s the twist: not all plant-based foods helped with weight loss. Eating ultra-processed vegan foods—like packaged snacks or microwaveable meals—did not produce the same benefits.
In fact, the real key to losing weight was minimizing both animal and plant-based ultra-processed foods. Instead, the focus should be on fresh, low-fat whole foods.
Simply going vegan won’t guarantee weight loss. What truly matters is cutting out ultra-processed junk, regardless of whether it’s plant-based or not.
Think about it: even if something is vegan, packaged snacks, sweets, and convenience foods are still loaded with added sugar, salt, and fat. These ingredients contribute to weight gain, no matter the source.
So what should your meals look like? Build your plate around fresh vegetables, fruits, legumes, and whole grains. These are the real champions of a healthy plant-based diet.
The study has limits—but the message is clear
Of course, the study isn’t without flaws. Participants self-reported their food intake, which may have introduced errors or inaccuracies. Also, the sample group may not represent the general population.
Still, the takeaway is clear: cutting processed foods—whether vegan or not—makes a big difference in weight management. More studies on larger, more diverse groups will help confirm this.
