Ultra-Processed or Not, Ditching Meat for Plant-Based Foods Can Help You Lose Weight: Study

A new study shows that swapping meat with plant-based alternatives – no matter how processed – can lead to significant weight loss.

The backlash against ultra-processed foods (UPFs) has cast a dark cloud over plant-based meat alternatives, which have been bundled in the same group as sugary sodas, salty snacks, and packaged cakes and muffins.

For many, UPFs have now become synonymous with unhealthy food, confirming the fears of many nutritionists who have warned against correlating processing with nutrition. In that vein, meat analogues have obtained a bad rep in some circles, despite containing less saturated fat, more fibre, and an equivalent amount of protein compared to animal products.

Meanwhile, the rise of obesity and Ozempic are making Americans rethink the way they eat. Brands are responding with products supporting GLP-1 drug users, while consumers are cutting back on foods high in fat, salt or sugar.

And according to a new study by the Physicians Committee for Responsible Medicine (PCRM), swapping meat with plant-based foods, whatever the level of processing they may have gone through, can lead to significant weight loss.

“Our research shows that choosing a bagel instead of bacon for breakfast or a veggie burger instead of a hamburger for dinner is the best option if you are looking to lose weight,” said Hana Kahleova, director of clinical research at PCRM.

Cutting out meat and dairy the top cause of weight loss

UPFs are a part of the Nova classification, which groups foods based on the level of processing. The first category comprises unprocessed or minimally processed foods (like fruits and vegetables), the second contains ‘processed culinary ingredients’ (like nut and seed oils, or salt), and the third is made up of processed foods with enhanced shelf lives (think tinned fish, salted nuts, breads and cheeses).

Foods produced via industrial techniques like extrusion or pre-frying, as well as those with cosmetic additives, are placed in the final category. These UPFs include everything from ice creams, sugary cereals, and packaged breads, to sausages, reconstituted meats, and plant-based analogues.

PCRM’s research – published in the peer-reviewed Nutrition & Metabolism journal – is a secondary analysis of a 2020 study that assigned 244 overweight participants to an intervention or control group for 16 weeks, with those in the former adopting a low-fat plant-based diet with no calorie limit.

That study suggested that the intervention group boosted their metabolism, lost weight, and improved their cardiometabolic risk factors, compared to those in the control group (who had made no dietary changes).

This new analysis specifically looked at the role of processed foods, categorising all foods consumed by the participants using the Nova system. PCRM found that the top three predictors of weight loss were reduced consumption of processed animal foods (like smoked fish), unprocessed or minimally processed animal proteins (like milk, beef or eggs), and animal-derived UPFs (like cheese or fried chicken).

A ‘reminder’ that processed vegan food can be healthy

The intervention increased the consumption of plant-based food against a decrease in animal proteins across all four Nova categories. And no amount of processing showed any sign of impact on weight when it came to vegan products.

Each 50g reduction of processed animal-derived foods per day resulted in a loss of 1kg, as did a 63g decrease in unprocessed animal proteins and a 120g reduction in animal-based UPFs.

Participants following a vegan diet shed an average of 5.9kg compared to the control group, confirming that swapping meat and dairy for plant-based foods was associated with “clinically significant weight loss”.

“Filling your plate with plant-based foods – even if they are considered ultra-processed like soy milk and vegan meat and yoghurt alternatives – instead [of] animal products can have a positive impact on your weight and overall health,” said Kahleova, who was the study’s lead author.

The researcher ascribed these findings to reduced fat and energy intake, higher fibre consumption, and calorie burn from increased after-meal metabolism.

“Our new study is an important reminder that plant-based foods that are considered processed, like canned beans, cereal, and veggie burgers, are actually part of a healthy diet that can help fight America’s diet-related chronic disease epidemics,” said Kahleova.