Less Food, More Sadness? Study Links Restrictive Diets To Depression

Researchers have found that restrictive diets that cut calories or certain nutrients may be linked to increased symptoms of depression, especially in men and overweight people. Diet affects not only the body, but also emotional well-being, and therefore dietary recommendations should be personalized.

Depression is an increasingly common mental health problem worldwide. Between 1990 and 2017, cases increased by about 50%.

It is characterized by a set of symptoms that affect mood, such as persistent sadness, loss of interest in activities, guilt, negative thoughts and even suicidal ideation, as well as physical symptoms such as insomnia, fatigue, changes in appetite and difficulty concentrating.

There are several factors that contribute to depression, some of which cannot be changed, such as age and biological sex, but diet is a factor that can be adjusted and has recently gained attention as a possible way to influence mental health.

Many people think of food as a way to take care of their bodies and lose weight. However, recent research shows that what we eat can also have a profound effect on our emotional well-being.

Several studies have compared “healthy” diets, which include natural foods, fruits, vegetables, whole grains, nuts, seeds, lean proteins and fish, with “unhealthy” diets, which include processed foods, refined sugar, fried foods, processed meats and sweets.

The general conclusion is that those who follow a more balanced diet tend to have a lower risk of developing symptoms of depression.

Despite this, this view that diet is simply “good” or “bad” may be too simplistic. People follow a wide variety of diets on a daily basis, which are not always ideal, but are more realistic.

In addition, some studies have focused on more specific eating patterns, such as the MIND diet (which combines the Mediterranean diet with the DASH diet and focuses on brain health), which has shown positive effects in reducing symptoms of depression in some populations.

However, few studies have investigated how different types of diets that people actually follow, such as calorie-restricted diets, diets that reduce sugar or fat, or diets to treat conditions such as hypertension or diabetes, impact mental health, especially in large and diverse populations such as the United States.

With this in mind, researchers at the University of Toronto, Canada, conducted a study based on data from more than 28,000 American adults, collected between 2007 and 2018. They analyzed information about these people's eating habits and symptoms of depression, measured by a standard mental health questionnaire.

The aim was to understand how different dietary strategies influence the risk of experiencing depressive symptoms, also taking into account the person's sex and body mass index (BMI).

The results showed that people who followed calorie-restricted diets (i.e., with fewer calories) had slightly higher scores for depressive symptoms compared to those who followed no diet.

This effect was even stronger in people who were overweight or obese, especially when they followed diets that also restricted certain nutrients, such as fat or sugar.

Men who were dieting also reported more physical symptoms of depression (such as fatigue and insomnia) than men who were not dieting. And men who followed nutrient-restricted diets reported more emotional symptoms, such as sadness and lack of pleasure, than women who were not dieting.

Based on these findings, the authors conclude that popular diets, even those with good intentions, such as those for weight loss or improving health, can have negative impacts on the mental health of some people, depending on their weight and gender.

Therefore, it is important that dietary guidelines take into account each person's individual profile, and that diets are not treated as a single, universal solution.

READ MORE:

Mental health consequences of dietary restriction: increased depressive symptoms in biological men and populations with elevated BMI

Gabriella Menniti, Shakila Meshkat, Qiaowei Lin, Wendy Lou, Amy Reichelt, and Venkat Bhat

BMJ Nutrition Prevention & Health. 3 June 2025

https://doi.org/10.1136/bmjnph-2025-001167

Abstract:

The literature primarily examines the mental health effects of dietary patterns, with ‘healthy’ diets linked to fewer depressive symptoms, although no standardised definition of a ‘healthy’ diet exists. Many individuals adopt restrictive diets such as caloric or nutrient restriction or medically prescribed patterns (eg, diabetic diets) to improve health, yet their impact on depressive symptoms remains understudied. This study aims to evaluate the association between restrictive dietary patterns and depressive symptoms stratified by sex and body mass index (BMI). A cross-sectional study was performed using the National Health and Nutrition Examination Survey (NHANES) 2007–2018. Adults who completed dietary assessments and the Patient Health Questionnaire-9 (PHQ-9) for depressive symptom severity were included. Statistical analyses were performed using R. Multivariable linear regression was used to examine associations, and interaction effects were explored by including BMI or sex, with subgroup analysis performed when appropriate. The study included 28 525 adults, of whom 7.79% reported depressive symptoms. Compared with individuals not following a specific diet, those adhering to calorie-restrictive diets had a 0.29 point increase in PHQ-9 scores (95% CI 0.06 to 0.52). Among overweight individuals, calorie-restricted diets were associated with a 0.46 point increase (95% CI 0.02 to 0.89) and nutrient-restricted diet was associated with a 0.61 point increase (95% CI 0.13 to 1.10) in PHQ-9 scores. Men who followed any diet showed higher somatic symptom scores than those not on a diet. Additionally, men on a nutrient-restrictive diet had a 0.40 point increase in cognitive-affective symptom scores (95% CI 0.10 to 0.70) compared with women not following a diet. There are potential implications of widely followed diets on depressive symptoms, and a need for tailored dietary recommendations based on BMI and sex.