Following a low-calorie diet could increase the risk of depressive symptoms, particularly among men and individuals who are overweight, according to new research published in BMJ Nutrition Prevention & Health.
The study analyzed data from over 28,000 adults in the US National Health and Nutrition Examination Survey (NHANES) from 2007 to 2018, assessing depressive symptom severity with the Patient Health Questionnaire-9 (PHQ-9).
Researchers categorized diets into calorie-restrictive, nutrient-restrictive, established dietary patterns (such as those adapted for diabetes), and no specific diet.
They found that those on calorie-restrictive diets had PHQ-9 scores 0.29 points higher than those not dieting, with overweight individuals on such diets showing an even greater increase in depressive symptoms.
The study highlights that while a healthy diet rich in whole foods generally lowers depression risk, restrictive diets may lead to nutritional deficiencies, physiological stress, and worsened mental health.
This contrasts with earlier randomized controlled trials that suggested low-calorie diets might improve mood, possibly because real-world dieting often lacks balanced nutrient intake and can involve weight cycling.
Men appeared especially vulnerable, with nutrient-restrictive diets linked to higher cognitive-affective symptoms (related to thoughts and feelings), and all diet types associated with increased somatic symptoms (physical distress and anxiety) in men.
Researchers suggest that men’s greater nutritional needs for brain-supporting nutrients like glucose and omega-3 fatty acids may explain this difference.
Professor Sumantra Ray, Chief Scientist at the NNEdPro Global Institute, noted that while the effect sizes are small and further research is needed, the findings raise important questions about the mental health impacts of restrictive diets low in key nutrients such as omega-3s and vitamin B12.
Practical suggestions:
Prioritize balanced, nutrient-rich diets including fruits, vegetables, whole grains, lean proteins, and healthy fats.
Avoid overly restrictive calorie or nutrient cuts without professional guidance.
Monitor mental health closely when changing dietary patterns, especially for men and those with higher BMI.
Seek advice from healthcare providers or dietitians to ensure nutritional adequacy during weight loss or health-focused diets.
This study underscores the complex relationship between diet and mental health and encourages a cautious, well-informed approach to dieting for both physical and psychological well-being.
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