A large-scale study published in BMJ Nutrition Prevention & Health has found that low-calorie diets may be linked to a higher risk of depressive symptoms, particularly in men and individuals who are overweight.
The findings suggest that while restrictive diets are popular for health and weight loss reasons, they could have unintended consequences for mental health.
It is widely accepted that healthy diets—rich in whole foods, fruits, vegetables, and lean proteins—are associated with lower depression risk. Conversely, unhealthy diets, laden with ultra-processed foods and refined sugars, tend to increase that risk. However, less is known about how calorie-restricted or nutrient-restricted diets impact mental well-being.
Researchers analyzed data from 28,525 adults participating in the U.S. National Health and Nutrition Examination Survey (NHANES) between 2007 and 2018. Participants completed the Patient Health Questionnaire-9 (PHQ-9), a tool for assessing depressive symptom severity. Roughly 8% of participants reported depressive symptoms, with 87% not on any specific diet.
The study categorized diets into four types: calorie-restrictive, nutrient-restrictive (low in fat, sugar, salt, etc.), established dietary patterns (e.g., diabetes-focused), and no diet.
The study found:
– PHQ-9 scores were 0.29 points higher in calorie-restrictive dieters versus non-dieters.
– Overweight individuals following calorie-restricted diets had scores 0.46 points higher.
– Nutrient-restrictive diets were linked to 0.61-point higher PHQ-9 scores.
– Men, in particular, exhibited stronger depressive symptoms with dietary restrictions.
Researchers speculate that in real-world settings, calorie-restricted diets often result in nutritional deficiencies and physiological stress—conditions that may contribute to worsening depression. This contrasts with previous studies based on controlled trials, where balanced nutrition was maintained despite reduced calories.
The gender differences may stem from higher nutritional needs in men. Nutrients like glucose and omega-3 fatty acids are essential for brain health and may be lacking in restrictive diets.
Professor Sumantra Ray from the NNEdPro Global Institute notes that although the effect sizes are small, the study raises vital questions about how restrictive eating patterns—especially those low in critical nutrients—might influence mental health. He calls for more well-designed studies to explore this area further.
While the study is observational and cannot confirm cause and effect, it highlights the potential mental health risks of low-calorie diets and underscores the importance of nutritional balance.
If you care about mental health, please read studies about One sleepless night can reverse depression for days and findings of Scientists find better treatment for older adults with depression.
For more about mental health, please read studies about Frequent painkiller use linked to mental health risks in these people and findings of Common depression drugs may offer new treatment for bipolar disorder.
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