Summary: New research finds an association between low-calorie and other restrictive diets and a small increase in depressive symptoms, particularly among men and people who are overweight. The large observational analysis evaluated diet patterns and depression scores in more than 28,000 U.S. adults using nationally representative survey data.
Participants reporting calorie- or nutrient-restrictive eating patterns had slightly higher scores on measures of emotional and physical distress than those not following a specific diet. The results indicate that unsupervised or self-directed restrictive diets in real-world settings may carry a modest negative impact on mental health for some groups.
Key Facts:
- Depression risk: Individuals on calorie-restrictive diets had higher PHQ-9 depression scores than those not dieting.
- Gender differences: Men on restrictive diets showed greater increases in emotional (cognitive-affective) and somatic symptom scores than women.
- Obesity and overweight: Overweight and obese participants following restrictive diets experienced more pronounced depressive symptoms compared with those of healthy weight not dieting.
Source: BMJ
Following a low-calorie diet is associated with a modest increase in depressive symptoms, according to research published in the open-access journal BMJ Nutrition Prevention & Health.
The analysis suggests particular vulnerability among men and people with overweight or obesity. The authors note that dietary quality and nutrient balance are important considerations when evaluating mental health outcomes.
Previous evidence links overall dietary patterns with mental health: diets emphasizing minimally processed foods—fresh fruits and vegetables, whole grains, nuts, seeds, lean proteins, and fish—are generally associated with lower depression risk, while diets high in ultra-processed foods, refined carbohydrates, saturated fats, processed meats, and sweets are commonly linked with higher risk.
However, people adopt many other patterns for health or medical reasons, including diets that limit calories or specific nutrients. It has been unclear whether these restrictive patterns relate to depressive symptoms in routine, non-research settings. To investigate, the researchers analyzed data from 28,525 adults (14,329 women and 14,196 men) who participated in the U.S. National Health and Nutrition Examination Survey (NHANES) from 2007–2018 and completed the Patient Health Questionnaire-9 (PHQ-9) for depressive symptom severity.
In the sample, 2,508 people (just under 8%) reported depressive symptoms. Weight status among participants was: 7,995 (29%) healthy weight, 9,470 (33%) overweight, and 11,060 (38%) obese.
Respondents were asked whether they followed any specific diet to lose weight or for other health reasons and, if so, to select from nine diet options included across the NHANES cycles. Researchers grouped reported patterns into four categories: (1) calorie-restrictive; (2) nutrient-restrictive (e.g., low in fat/cholesterol, sugar, salt, fiber, or carbohydrates); (3) established dietary patterns (for example, diets adapted for diabetes); and (4) not on a diet.
Most participants (25,009; 87%) reported not following any specific diet. Of the rest, 2,026 (8%) followed a calorie-restrictive diet, 859 (3%) a nutrient-restrictive diet, and 631 (2%) an established dietary pattern. When examined by sex, a larger share of men (12,772; 90%) than women (12,237; 85%) reported not being on any diet. Calorie restriction was reported most often by people with obesity (1,247; 12%) and those who were overweight (594; 8%).
On average, PHQ-9 scores were 0.29 points higher among those on calorie-restricted diets compared with participants not following any diet. The effect was more pronounced among those who were overweight: PHQ-9 scores were 0.46 points higher for overweight individuals following calorie restriction. Nutrient-restrictive diets were associated with a 0.61-point increase in PHQ-9 scores among overweight participants.
Specific symptom domains also differed by diet type. Calorie-restrictive diets correlated with higher cognitive-affective symptom scores (thoughts and feelings), while nutrient-restrictive diets were associated with higher somatic symptom scores (physical distress and anxiety about bodily symptoms). These associations varied by sex: nutrient-restrictive diets were linked to higher cognitive-affective symptom scores in men compared with women not on a diet, and all three diet types were associated with higher somatic symptom scores in men. People with obesity following an established dietary pattern also showed higher cognitive-affective and somatic symptom scores than healthy-weight non-dieters.
The authors emphasize that this is an observational study and cannot establish causality. Self-reported diet classification may be imprecise. The findings contrast with some randomized controlled trials that found improvements in depressive symptoms with calorie reduction; the discrepancy may reflect differences between carefully designed, nutrient-balanced diets in trial settings and real-world restrictive diets that can lead to nutrient deficiencies (for example in protein, vitamins, or minerals) and physiological stress.
Other possible explanations include failure to achieve weight loss goals or weight cycling—repeated loss and regain of weight—which may worsen mood. The researchers also note that nutrients such as glucose and omega-3 fatty acids are important for brain function; diets low in carbohydrates or essential fats could theoretically impair cognitive-affective functioning, potentially affecting men more in this sample.
Professor Sumantra Ray, Chief Scientist and Executive Director of the NNEdPro Global Institute for Food, Nutrition and Health, which co-owns BMJ Nutrition Prevention & Health with the BMJ Group, commented that the study contributes to growing evidence linking diet and mental health. He cautioned that effect sizes are small and that statistical limitations affect generalizability, underscoring the need for further, well-designed studies that accurately capture dietary intake and minimize confounding.
About this diet and depression research news
Author: Caroline White
Source: BMJ
Contact: Caroline White – BMJ
Image: The image is credited to Neuroscience News
Original Research: The findings will appear in BMJ Nutrition Prevention & Health.