New research suggests that cutting calories too aggressively may take a toll on mental health. In a large U.S. study, adults following low-calorie or nutrient-restrictive diets reported more depressive symptoms than those not on a specific diet. Men and individuals living with overweight or obesity appeared most affected.
The study, published in BMJ Nutrition Prevention & Health, analyzed data from more than 28,000 adults who completed mental health questionnaires as part of the National Health and Nutrition Examination Survey.
Researchers found that people following calorie-restrictive diets had higher scores for depressive symptoms, particularly when those individuals were overweight. Nutrient-restrictive diets were also associated with increased symptoms, including physical complaints and mood-related issues.
“This discrepancy may arise because prior studies were primarily randomized controlled trials. ... In contrast, real-life calorie-restricted diets and obesity often result in nutritional deficiencies ... and induce physiological stress, which can exacerbate depressive symptomatology,” the authors explained.
In particular, the study found that men on restrictive diets scored higher on both cognitive-affective symptoms (such as sadness and hopelessness) and somatic symptoms (like fatigue and sleep issues), suggesting a broader impact on mental well-being.
Researchers emphasized that this was an observational study and cannot confirm causality. But the findings challenge earlier studies suggesting low-calorie diets improve mood. Differences in nutrient balance, weight cycling and individual nutritional needs may explain the contrast.
“This study adds to the emerging evidence linking dietary patterns and mental health,” said Professor Sumantra Ray of the NNEdPro Global Institute for Food, Nutrition and Health. “Further well-designed studies ... are needed to continue this important line of inquiry.”
The authors did not receive specific grant funding for this research from any public, commercial or nonprofit agencies. One author receives broader research support from multiple institutions, including the Canadian Institutes of Health Research and the Department of National Defence (Canada), among others.