Kelly Clarkson has dropped 37 pounds in the last year. She gives credit for her waist-shrinking success to a new, clean eating plan: the Plant Paradox diet.

In early June, Clarkson stunned fans and red-carpet guests with a slimmer physique at the CMT Music Awards. She later told “Today Show” host Hoda Kotb she decided to change her eating habits because she received a diagnosis of a thyroid condition and autoimmune disease.

The goal, the Grammy Award-winning singer and “The Voice” coach said, was never weight loss.

“For me, it wasn’t really the weight. For me, it’s I’m not on my medicine anymore,” she told Kotb. “My blood work came back, and I haven’t been on my medicine since February.”

“The Plant Paradox,” by Dr. Steven R. Gundry, claims that lectins — proteins present in many foods — are responsible for a variety of health ailments, from weight gain and leaky gut to inflammation and thyroid issues. This is why Clarkson used the diet. Eliminating lectins from your diet, Gundry suggests in his book, can reverse these complications.

Unfortunately, some of the foods most experts consider among the healthiest in the world contain lectin. These include fruits, vegetables, and grains.

That’s why this diet worries some nutrition experts and plant-based eating proponents.

What are lectins, and are they unhealthy?

Lectins are proteins found in about 30 percent of foods. Gluten, for example, is a type of lectin. They’re particularly abundant in plant foods.

For plants, lectins act as a natural defense against fungi and insects. In humans, Gundry says, the proteins attack the body, leading to numerous health and digestive problems.

“Lectins are known as pro-inflammatory and autoimmunity-triggering proteins,” said Dr. Luiza Petre, an assistant clinical professor of cardiology at Mount Sinai School of Medicine and a cardiology clinical instructor at New York University’s Langone Medical Center. “Once they enter the bloodstream, they trigger an autoimmune response. They can also directly irritate the intestinal lining, leading to leaky gut syndrome, or the condition where our gut is not working as an effective filter anymore.”

The Plant Paradox diet requires followers to eliminate lectin-rich foods, including:

  • soy
  • peanuts
  • quinoa
  • brown rice
  • potatoes
  • nightshade vegetables, such as tomatoes, peppers, and eggplant
  • most all fruit, except in-season berries and avocados
  • any dairy foods that are made from the milk of grain-fed cows

What’s left is pasture- and grass-fed meat, leafy greens, cauliflower, broccoli, Brussels sprouts, fish, and coconut oil. It might seem limited. But Gundry believes this is the key to restoring health for many individuals.

“[This diet] asks people to eat and party like it’s 9,999 years ago, before the dawn of agriculture,” Gundry, who’s a heart surgeon, told Healthline. “Humans thrived on this diet in the past and are thriving again as they return to their dietary roots and eliminate the ‘disruptors’ that have destroyed their gut microbiome.”

What does the research say?

Gundry describes “disruptors” as chemicals and environmental factors that wreak havoc on the body, including herbicides, certain medications that can have side effects, and artificial sweeteners.

However, research to support Gundry’s claims is very limited. Indeed, no human studies have verified his proposed theories.

Instead, he says, he has anecdotal evidence to support his claims.

“[Kelly Clarkson’s] experience is exactly like tens of thousands of patients who have followed the program,” he told Healthline. “In short, it works.”

But many medical experts are wary of relying on anecdotal evidence instead of published data.

Plus, the foods you’re required to give up for the Plant Paradox diet are considered some of the healthiest. That’s a problem for many nutritional experts.

“While any diet that is highly restrictive will likely help people lose weight in the short term, this diet unfortunately severely limits the intake of many foods central to a plant-based diet,” said Dr. Nicole Harkin, FAAC, a board-certified cardiologist and lipidologist and clinical assistance professor at Columbia University.

She points out there’s good data about the type of diet that’s healthy for the brain and heart.

“While there is little to no evidence that a lectin-free diet is healthy for you, there are an abundance of studies indicating that a whole-food, plant-based diet is good for your heart and brain,” Harkin said.

Eating healthier

For Clarkson, her adherence to the Plant Paradox diet required her to eliminate a lot of processed and packaged foods.

Eliminating processed foods can cut calories, reduce sugar intake, and help you shed unwanted pounds. That step alone could be a successful option for most people.

Clarkson told Kotb in her “Today Show” appearance that it also helped her gain an understanding of the quality of food she was eating.

“It’s about understanding food and what we do to food, like spraying and pesticides and genetically modified and hormones we pump in,” the 36-year-old mother of four told said.

If eliminating all of these foods for a diet feels overwhelming or complicated, keep in mind that cooking destroys lectins.

“It seems unrealistic to eliminate these foods entirely from your diet, as there are ways to prepare them and lower lectin content while reaping the benefits of fiber, vitamins, and other antioxidants,” Petre said.

Soaking, pressure cooking, removing seeds, peels, or sprouting, fermenting, and adding bicarbonate are all ways you can reduce the lectin content of your favorite foods, Petre says. Indeed, much of the lectin in foods is destroyed long before you eat it.

“My advice is to cut the processed and packaged food, as the Plant Paradox diet recommends, but don’t miss out on all of the antioxidants, fiber, and phytonutrients found in fruits, legumes, whole grains, and vegetables,” Harkin added.