Yes, there are certain foods that cats should avoid. Cats should not eat foods that are high in fat, sugar, or salt, as these can cause gastrointestinal problems. Additionally, cats should not eat chocolate, onions, garlic, grapes, or raisins, as these can be toxic to cats. Signs of dietary problems in cats can include vomiting, diarrhea, weight loss, and decreased appetite. If you notice any of these symptoms in your cat, it is important to take them to the vet as soon as possible.