Keeping Fit: Does a plant-based diet work as well as the new weight-loss drugs?

Published 1:00 pm Tuesday, April 1, 2025

The newest class of weight-loss drugs, GLP-1 agonists like Victoza, Wegovy or Ozempic, have seen explosive growth in the past few years. And it is understandable to see why. Boasting up to 15% bodyweight losses, or about 30 pounds for a 200-pound person, these drugs have been a breakthrough for a lot of people.

However, for an equally large number of people who try the drugs but then discontinue them within the year they have been a bust. Much of this is because of the common side effects (nausea, vomiting, diarrhea and heartburn) but some is also because these drugs are pricey and not always covered by insurance. Nevertheless, if you discontinue them, the studies show the weight comes right back. Ugh! Fortunately, for those who are willing to adopt it, a healthy plant-based (vegan) diet may offer even better long-term success.

The most successful weight-loss trial

In 2017, the journal Nutrition and Diabetes surprised the scientific world by publishing results that showed people could eat as much as they wanted of a low-fat, whole (unprocessed), plant-based diet and still lose weight. In fact, with no calorie counting or restrictions whatsoever they lost on average 26 pounds in just the first six months. That appears awfully close to the results the new weight-loss drugs promise.

But it is at this point, in most dieting studies, that participants start gaining back the weight so that the typical weight loss after one year is just 5% at best (maybe a 10-pound weight loss). However, in the “BROAD study: a randomized, controlled, community-based trial of a whole-food, plant-based diet,” the participants kept the weight off. With no extra effort at counting calories, or even extra exercise, these people maintained an almost 13% bodyweight loss. That’s very close to the results that can be expected by most of the new weight-loss drugs. And this is with none of the awful side effects, or even gnawing hunger, since the participants were allowed to eat all they wanted. The only catch? You had to stay away from the processed foods and animal foods our culture loves.

Safer and cheaper?

However, for those who find they can embrace this lifestyle long-term, research shows the benefits are even greater. For example, in the Adventist Health Study-2, which included more than 60,000 adults, the typical body mass index (BMI) of those following vegan diets was 23.6, compared with 28.8 for those following omnivorous diets. That’s a difference of about 36 pounds. Which is even more than can be expected on the new weight-loss drugs.

And in contrast to the cost of Wegovy, which can easily exceed $15,000 a year without insurance, a randomized study published in JAMA Network Open in 2023 found that a vegan diet saved about $500 annually in grocery bills. So not only does a whole-food, plant-based diet offer weight-loss benefits very close to the newest weight-loss drugs, it does it without the side effects, and saves you money, too.

The bottom line

Whole-plant foods, because of their increased fiber and intact cell walls, already naturally stimulate more GLP-1 secretion in the lower portions of your bowels than processed foods can ever do. With their bulk, they also stimulate satiety on far fewer calories, and the side effects include reduced cholesterol and blood sugar and decreased risk of diabetes, heart disease and even dementia.

Even if you choose to use one of the newest weight-loss drugs, a more plant-based diet will likely improve your health, possibly lessen unpleasant side effects and decrease your possibility of gaining much of the weight back if you ever go off the drugs.

For most people, adopting a healthier, plant-based diet is a simple matter. Those looking for guidance can find it online at places like nutritionstudies.org, nutritionfacts.org or the Physicians Committee for Responsible Medicine (pcrm.org).

Thomas Morrison is a fitness coordinator at the Bradley Wellness Center.