Doctor of integrative medicine and bestselling author Andrew Weil says the Keto diet is a trend that could be dangerous.

“I think it’s a fad, I don’t think it will last and I don’t think it’s a healthy way to eat for a length of time,” Dr. Weil tells PEOPLE at an event for True Food Kitchen, a restaurant chain he co-founded that bases its menu on his anti-inflammatory diet.

Ketosis — a normal process in the body that occurs when there is no glucose to burn for energy, so the body burns fat — “is an abnormal state; it’s a starvation state” he says. “You’re eliminating carbohydrates  — it’s not a good idea to cut out a whole macronutrient. I think there’s a risk of getting serious deficiencies,” says Dr. Weil, Director and Clinical Professor of Medicine at the University of Arizona Center for Integrative Medicine.

“It represents a misunderstanding,” he adds. “There are good and bad carbs. There are a lot of carbs that people eat that are going to promote weight gain and reduce insulin sensitivity and you want to learn the differences in kinds of carbohydrates so you limit the [bad carbs] that you eat but you don’t eliminate them totally.”

Dr. Weil points out that another popular diet, Paleo, keeps people from eating beans, while they are “a good source of fiber that’s slow digesting. They have protein and a lot of minerals. To say you don’t eat beans because they’re carbs, that’s silly to me.”

But he agrees that cutting back on some carbs is a healthy way to lose weight. “The simplest advice to people who want to lose weight is to stop eating foods made from flour and sugar.”

He also says there’s a misunderstanding when it comes to whole grains. “When I ask the average American to name a whole grain food, the answer I get is wheat bread. Wheat bread is not a whole grain food. It’s basically white bread with color.”

He recommends quinoa, rice, buckwheat oats and cracked wheat to get in whole grains. “The starch in grains is tightly compacted and it’s enclosed more or less by a fibrous hull and it has some fat in the germ. The fat slows emptying from the stomach and the bran, the coating, and it makes it hard for the digestive enzymes to get in and convert it from starch to sugar.” This is better for blood sugar and less likely to result in weight gain.

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But with milled grain, like flour and sugar, “the starch is turned into a material with an infinite surface area and it’s a snap for enzymes to turn that from starch into sugar.” These are the kinds of carbs that raise blood sugar and make people gain weight, he says.

He recommends fruits and vegetables as the primary part of a healthy diet in his anti-inflammatory food pyramid, with whole and cracked grains, pasta al dente, beans, healthy fats and fish and shellfish making up the other main sources of nutrients.

Dr. Weil also says people should eat a little bit of everything and enjoy food. “A lot of Americans look at the table as a minefield: You make one mistake and you go to nutritional hell,” he says. “People on these rigid diets don’t look like they’re enjoying food.”