Study Links Caloric Restriction to Depression Risk

For anyone who’s tried to swap out cookies for carrot sticks, the struggle of dieting is all too familiar—and not particularly enjoyable. A new study has shed light on this issue, revealing that cutting calories is associated with a higher risk of depression, particularly in men.

Researchers from the University of Toronto reviewed data from 28,528 adults in the U.S. over ten years. These individuals provided information about their daily food consumption, any diets they followed, and underwent clinical assessments for depression.

Those on low-calorie diets reported more depressive symptoms, such as fatigue, issues with focus, and a decreased interest in enjoyable activities. The study’s authors suggested this might stem from nutritional deficiencies—such as a lack of protein and vitamins—that could negatively impact brain function and lead to low mood. They also pointed out that not seeing results or experiencing weight fluctuations during dieting could further exacerbate depressive feelings.

The findings were particularly pronounced in men. This could be linked to their greater nutritional requirements and possibly the belief that dieting is more challenging for them than for women.

In the journal BMJ Nutrition Prevention & Health, the researchers noted that restrictive calorie diets are uniquely associated with increased depressive symptoms compared to those who are not dieting. They emphasized the importance of adequate glucose and omega-3 fatty acids for brain health, suggesting that dieting may lead to a decline in cognitive function and contribute to stress and depression.

Participants filled out a clinical depression survey, the PHQ-9, which scores up to 27. Close to ten percent were on calorie-restrictive diets, and those participants scored an average of 0.29 points higher in depression than those not dieting, with men showing more severe symptoms.

The researchers proposed that because biological men generally have higher calorie needs, following restrictive diets might impact their mood differently than it does for biological women. They also noted that men often gravitate towards richer, fatty foods and enjoy dining out more frequently, potentially making dieting feel even more challenging and leading to increased feelings of depression.

This study was observational, so it doesn’t establish a clear cause-and-effect relationship. Experts believe that additional trials are necessary to further explore the connection between dieting and mental health.

Professor Sumantra Ray from the NNEdPro Global Institute for Food, Nutrition and Health commented on the findings, reiterating the emerging evidence linking dietary choices to mental health. She raised concerns about whether nutrient-poor, restrictive diets might contribute to depressive symptoms.

However, she cautioned that the effect sizes observed were relatively small, and highlighted the need for further, more rigorously designed studies to better understand the relationship between diet and depression.