Abstract With the emergence of support for diet in the maintenance of cognition, clinicians have been justifiably eager to promote diet recommendations for their older patients. But popular diets, such as the Mediterranean diet, Dietary Approaches to Stop Hypertension (DASH), and the Mediterranean‐DASH Intervention for Neurodegenerative Delay (MIND), have not been shown to benefit cognition among patients who already have dementia or cognitive decline. In our experience, promoting these restrictive diets can be detrimental to patients with dementia who are already prone to eating disturbance; vulnerable to malnutrition; and, if underweight, demonstrate increased mortality. Moreover, we have seen both patient and caregiver satisfaction negatively affected by dietary modification. Clinicians need to be aware that any dietary recommendations for patients with dementia should be mitigated by the lack of evidence for improvement in cognition, the risks for exacerbating poor nutrition, and the potential for further limiting their quality of life.