Do you ever feel mentally exhausted during the day, even if you’ve had enough sleep? Do you get cranky or unable to function before lunch or mid-afternoon, until you eat something? Or maybe you’re having a hard time learning how to use a new electronic device and chalk it up to “getting old.”

These are just some of the symptoms of eating unhealthy seed oils (aka vegetable oils), according to Catherine Shanahan, MD, best known as Dr. Cate and author of The Fatburn Fix and Deep Nutrition. Other side effects of such fats can include weight gain, anxiety, mood problems, migraines, and other types of headaches.

Seed oils are the most common fats in foods that come in packages and on restaurant menus and they make up the largest share of fat in the typical American diet. But this doesn’t make them healthy.