In his book, The Plant Paradox, Steven Gundry, M.D., a cardiologist and heart surgeon based in Southern California, claims that any food with the plant protein lectin is your worst enemy when it comes to weight loss.
But here’s the thing about lectins: They’re found in foods you’ve always thought good for you—like whole grains, squash, tomatoes, beans, nuts, and a lot of animal proteins. And that’s just the short list.
Gundry claims that humans weren’t intended to eat foods containing lectins and that eliminating those foods can decrease inflammation, boost weight loss, and lead to an overall healthier lifestyle. But is this really legit? We talked to Gundry and a few experts to find out.
So, what are lectins?
Lectins are proteins naturally found in many foods, especially grains and beans. They like to bind to carbohydrates, which can help cells interact and communicate with each other.
In plants, lectins play defense.They’re how plants protect themselves against being eaten. By making insects and animals feel sick to their stomach, lectins discourage them from eating lectin-filled plants again.
In humans, Gundry says that eating lectins provokes an inflammatory response—which can lead to weight gain and other serious health conditions, such as leaky gut and irritable bowel syndrome (IBS).
What is the lectin-free diet?
“The lectin-free diet takes out high lectin foods like grains, quinoa, legumes, and nightshade vegetables like tomatoes, peppers, and eggplant,” says registered dietitian Amy Goodson.
Also on the do-not-eat list: dairy, out-of-season fruit, and conventionally-raised meat and poultry. Womp, womp.
Instead, the diet suggests you load your plate with low-lectin foods like leafy greens, veggies like cauliflower, broccoli, and asparagus, mushrooms, nuts and seeds, millet, pasture-raised meats, and wild-caught fish.
Can it actually help you lose weight?
Gundry says that he’s personally lost 70 pounds on a lectin-free diet, and that he’s put many of his patients on this plan as well. “The amazing thing is when people change nothing except removing major lectins, they start losing weight and they still are eating lots of calories, but we’re not storing it as fat anymore,” Gundry says.
He also cites a 2006 study that indicates that a lectin-free diet can have a positive effect on people with cardiovascular disease and metabolic syndrome (a group of conditions indicated by increased blood pressure, high blood-sugar levels, excess body fat around the waist, and abnormal cholesterol levels).
However, other experts are skeptical about how effective it is. “Anytime a diet starts to take out a massive amount of food groups, it’s a little more faddish by nature,” says Goodson. “The benefits of eating whole grains and vegetables, which provide vitamins, minerals, and fiber, significantly outweigh the risk that a small amount of lectin will cause GI issues.”
Plus, most foods with lectins can be super beneficial for weight loss, says Samantha Cassetty, R.D. For example, one 2017 study published in the American Journal of Clinical Nutrition linked whole grains with weight loss. And another study published in the same journal found that people who consumed pulses over a six-week period (a.k.a. beans, lentils, chickpeas) lost significantly more weight than those who didn’t consume any pulses.
However, Leah Kaufman, R.D., has seen weight-loss success in patients with IBS through eliminating certain lectin-containing foods via a low FODMAP diet, which cuts out foods like beans and starchy vegetables.
Goodson does admit that lectins can be troublesome in high quantities, or when you eat lectin-rich foods raw. “But I don’t know who eats chickpeas or quinoa raw,” she says. In fact, simply soaking beans and grains overnight and cooking them reduces the amount of lectins that can cause GI distress. Peeling and de-seeding nightshades can help too.
Plus, there are many different types of lectins. Some are anti-microbial and may have anti-cancer potential (woot!), while other lectins aren’t so good for you. But research is a little iffy on both sides. “The majority of research [on lectins] have been animal and in vitro studies, not studies in humans,” says Goodson. So take the findings with a grain of salt.
Should you ditch lectin?
While going lectin-free may help some people, it likely won’t solve everyone’s stomach issues. “It’s not one of those things that should be applied globally,” says Goodson. “If you’re having serious issues, talk to your doctor or see a registered dietitian.”
Plus, only 10 percent of Americans get the recommended daily amount of fruits and vegetables, says Goodson, so we should eat more, not less produce. “If you look at the benefits of fruits, vegetables, and whole grains for heart health and lowering disease risk, I’m going to argue that a little bit of fruit and vegetables are going to help people versus harm them,” says Goodson.
LIMIT THE INTAKE OF THE LECTIN-RICH FOODS
1. Beans & Legumes – Beans carry more lectins than any other food. Do your best to limit beans, peas, lentils, and other legumes or cook them in a pressure cooker. Also, some legumes hide as nuts – so it’s best to cut out peanuts and cashews as well.
2. Grains – For the most part, grains are a relatively new food to us. Our hunter-gatherer ancestors didn’t search for grains. Plus, most grains are lectin bombs, as well as gluten-free grain substitutes. It’s best to limit grain intake. If you must, eat white flour over wheat.
3. Squash – An easy rule to remember is that any vegetable with seeds is actually considered a fruit. Such is the case with squash, pumpkins, and zucchini. The seeds and peels of these foods are full of lectins. If you MUST eat squash, make sure to toss the peels and seeds aside.
4. Nightshades – Nightshades are vegetables that include eggplant, any kind of pepper, potatoes, and tomatoes. The peels and the seeds of these plants contain loads of lectins, too. Make sure to peel and deseed them or pressure cook or ferment them. All these techniques reduce the amount of lectins.
5. In-Season Fruit – Again, it’s nature’s candy, so you’ll want to limit the quantity you eat, but when it’s in season, fruit is okay to add to your diet.