"I'm like 37 pounds [17 kilograms] lighter in my pleather," said Kelly in an interview with NBC's Today show.
Kelly credits that weight loss to simply eating better—no exercise necessary. “I literally read this book, and I did it for this autoimmune disease that I had and I had a thyroid issue, and now all my levels are back up,” she said. “I’m not on medicine anymore because of this book,” Kelly told Extra.
That book she's referencing is called The Plant Paradox by doctor Steven Gundry and “it’s basically about how we cook our food, non-GMO, no pesticides, eating really organic...Literally, I haven’t worked out at all," she said.
But, while she admits the diet helped her drop kilos and feel healthier overall, Kelly still had some real talk for the diet (and healthy eating in general): "Honestly, I'm gonna be real with you: It's really expensive to do," she said. "I was poor growing up, and there's no way my family could have afforded this."
Clearly this is working for Kelly, but what’s The Plant Paradox about, anyway?
Gundry's a cardiac surgeon who says on his website that certain health foods like fruits and vegetables can harm your body by producing lectins, which he calls “toxic chemical compounds.”
“When lectins invade our bodies, they can cause some serious inflammatory responses and other health issues, like leaky gut syndrome, weight gain, brain fog, and more,” Gundry writes on his website.
His book provides a list of foods and ingredients that he says don’t do this, including vegetables like broccoli and cabbage, along with fish and pasture-raised poultry. Fruits, however, are limited: only in-season berries and avocados get the green light.
So, can cutting out lectins help you lose weight?
Honestly, probably not any more than any other diet.
“The book is based on the premise that lectins in grains, beans, peanuts, and other plant-based foods are pro-inflammatory,” says Julie Upton, R.D., co-founder of nutrition website Appetite for Health. “But there’s no good evidence that this actually the case.”
It should also be noted that a lectin-free diet restricts many, many foods that really are good for you, like whole grains, most fruits, and nuts.
There is strong evidence, however, that the healthiest people tend to focus on plant-based diets—lectins included—so it’s tough to make a solid case that eating fruits and vegetables that contain lectins are going to harm you.
“I suspect Kelly Clarkson has lost weight by following an eating style that has fewer calories than what she was previously eating,” Upton says. “When people lose weight, if overweight, they tend to feel better and most health biomarkers improve, too.”
Okay, but what about her thyroid condition?
Kelly didn’t give details on her thyroid condition, or what medication she was taking for it. Treatment for hypothyroidism, however (an underactive thyroid and often the cause of weight gain) generally involves medication like synthetic hormones to alter thyroid levels, the Mayo Clinic says.
And while some doctors may prescribe an alternative medicine—specifically prescription-only natural extracts—in lieu of synthetic hormones, per the Mayo Clinic, it's not suggested that diet alone can manage thyroid conditions.
The bottom line: If Kelly's weight loss has prompted you to revamp your own diet, it's a good idea to focus on more plant-based meals—and to just ignore those "harmful lectins" for now.
This article originally appeared on Women's Health US