A new study published in BMJ Nutrition Prevention & Health has found that low-calorie or restrictive diets may be associated with a higher risk of depressive symptoms, particularly in men and people who are overweight or obese. The findings challenge previous research and highlight the potential mental health costs of calorie-cutting diets, especially when followed without proper nutritional guidance.Healthy vs. Unhealthy Diets: What We KnowTraditionally, diets rich in whole foods—such as fruits, vegetables, whole grains, nuts, lean proteins, and fish—are linked to lower risks of depression. On the other hand, diets high in ultra-processed foods, refined sugars, saturated fats, and processed meats are associated with a greater risk of mental health issues. However, not all diets fit neatly into these categories, and many people follow restrictive eating plans for various health reasons. This new study set out to explore whether these restrictive diets themselves may be linked to depressive symptoms.The Study: Diet Patterns and Depression ScoresResearchers analyzed data from 28,525 adults who participated in the US National Health and Nutrition Examination Survey (NHANES) between 2007 and 2018. Participants also completed the PHQ-9 questionnaire, a standard tool used to assess the severity of depressive symptoms.About 8% of participants reported depressive symptoms. Diet types were grouped into four categories:Calorie-restrictive dietsNutrient-restrictive diets (low in fat, sugar, salt, fibre, or carbs)Established diets (such as diabetic diets)No specific dietThe majority—87%—were not following any specific diet. Only 8% reported being on a calorie-restrictive diet, and even fewer followed nutrient-restrictive (3%) or established (2%) dietary plans.Key Findings: Dieting and Depressive SymptomsThe results showed that people on calorie-restrictive diets had slightly higher PHQ-9 depression scores than those not on a diet. The differences were more significant among overweight individuals and men.Overweight individuals following calorie-restrictive diets had PHQ-9 scores 0.46 points higher.Nutrient-restrictive diets led to a 0.61-point increase in depressive scores in the same group.Men on nutrient-restrictive diets had higher cognitive-affective symptoms (thoughts and feelings linked to depression) compared to women.All three diet types were associated with higher somatic symptoms (physical symptoms linked to emotional distress) in men.Possible Explanations and LimitationsResearchers noted that participants might have inaccurately reported or classified their diets. Unlike clinical trials, real-life calorie-restricted diets often lack adequate nutrients, leading to deficiencies that could affect mental health.The researchers suggest that poor nutrient intake, weight cycling, and physiological stress might contribute to the link between dieting and depression. They also highlight the role of nutrients like omega-3 fatty acids and vitamin B12 in supporting brain function—nutrients that may be lacking in restrictive diets.While the effects seen in the study were modest, the findings add to growing concerns about the mental health impact of restrictive diets. Experts stress the need for well-designed studies that accurately assess diet and mental health links, particularly among vulnerable groups.