Low Calorie Diets May Trigger Depression in Men

Following a low calorie diet could increase your risk of developing depressive symptoms, particularly if you’re a man or overweight, according to new research analyzing nearly 30,000 Americans.

The study, published in BMJ Nutrition Prevention & Health, found that people on calorie-restricted diets scored higher on depression screening tests compared to those not following any specific eating plan. Men appeared especially vulnerable, showing increased depression-related symptoms across multiple types of restrictive diets. The findings challenge common assumptions about the mental health benefits of dieting and suggest that real-world calorie restriction may have unintended psychological consequences that differ dramatically from controlled laboratory studies.

The Depression-Diet Connection

Researchers analyzed data from the National Health and Nutrition Examination Survey spanning 2007 to 2018. Among the 28,525 participants, those following calorie-restrictive diets showed a 0.29 point increase in depression scores using the validated Patient Health Questionnaire-9 scale.

The effect was more pronounced in specific groups. Overweight individuals following calorie-restricted diets experienced a 0.46 point increase in depression scores, while those on nutrient-restricted diets saw a 0.61 point jump. To put this in perspective, clinical depression typically begins at scores of 10 or higher on the 27-point scale.

What makes these findings particularly concerning is how they contradict previous research suggesting that low calorie diets improve mood. The key difference appears to be between carefully controlled laboratory studies and real-world dieting experiences.

Why Real-World Dieting Differs

Previous studies showing mood benefits from calorie restriction were primarily randomized controlled trials where participants followed carefully designed diets with balanced nutrition. In contrast, real-life calorie restriction often leads to nutritional deficiencies and physiological stress.

The researchers noted that real-world calorie-restricted diets frequently result in deficiencies of protein, essential vitamins, and minerals. These nutritional gaps can worsen depression symptoms, particularly the cognitive and emotional aspects of the condition.

Another factor may be the psychological impact of failed weight loss or weight cycling—losing weight only to regain it. Unlike controlled studies where participants typically lose weight successfully, real-world dieters often struggle with adherence and may become frustrated when results don’t match expectations.

Men Face Higher Risks

The study revealed striking gender differences in how restrictive diets affect mental health. Men following any type of restrictive diet showed higher scores for somatic depression symptoms—physical manifestations like fatigue, sleep problems, and appetite changes.

Men on nutrient-restrictive diets also experienced increased cognitive-affective symptoms, including depressed mood, feelings of guilt, and concentration difficulties. This represented a 0.40 point increase compared to women not following any special diet.

Several factors may explain men’s vulnerability. Males typically have higher nutritional requirements, making them more susceptible to deficiencies when restricting food intake. Additionally, men often prefer high-fat foods and frequent fast-food restaurants more than women, making nutrient restrictions particularly challenging.

The Brain Chemistry Factor

The researchers suggested that glucose and omega-3 fatty acids are critical for brain health. Diets low in carbohydrates or fats may worsen brain function and exacerbate depression symptoms, especially in men with greater nutritional needs.

This biological explanation aligns with research showing that men have different brain activation patterns during risky decision-making compared to women. Men often show activation in multiple brain regions, potentially making them more sensitive to nutritional disruptions affecting neural function.

The study also found that deficiencies in essential nutrients like vitamin B12, folate, and iron can impair energy metabolism, worsening the physical symptoms of depression that men experienced more severely.

The Weight Factor

Overweight individuals faced particular challenges with restrictive eating. Both calorie-restricted and nutrient-restricted diets were associated with higher depression scores in this group, contradicting research suggesting that weight loss improves mood.

The key difference appears to be actual weight loss success. Controlled studies often achieve better adherence to diets and more successful weight reduction. In real-world settings, barriers like insufficient support and motivation frequently prevent successful weight loss.

When overweight individuals diet without losing weight—or experience weight cycling—they may develop worsening depression symptoms. This creates a potentially harmful cycle where the very tool intended to improve health outcomes leads to psychological distress.

The Somatic Symptom Pattern

Overweight participants following nutrient-restricted diets showed particular increases in somatic depression symptoms. These physical manifestations included low energy, poor sleep quality, and concentration difficulties—symptoms that align with existing research linking restrictive dieting to physical health problems.

The somatic symptoms may reflect the body’s stress response to nutrient restriction, particularly when individuals are already dealing with the metabolic challenges associated with excess weight. This physiological stress can manifest as depression-like symptoms even when mood itself isn’t severely affected.

Beyond Simple Healthy vs. Unhealthy

The research challenges the oversimplified “healthy diet good, unhealthy diet bad” narrative that dominates nutrition discussions. While previous studies consistently show that diets rich in whole foods reduce depression risk, this study reveals that the method of dietary change matters as much as the end result.

Most participants—87% of the nearly 30,000 studied—weren’t following any specific diet plan. Among those who were dieting, 8% followed calorie-restrictive approaches, 3% used nutrient-restrictive methods, and just 2% adhered to established dietary patterns like diabetic diets.

Interestingly, established dietary patterns showed no association with depression scores, suggesting that medically supervised or well-defined eating plans may be safer for mental health than self-directed restriction efforts.

The Classification Challenge

One limitation that extends beyond typical coverage involves how people classify their own diets. The study relied on self-reported dietary patterns, and participants may not accurately categorize what they’re actually eating.

For example, the researchers found that people reporting “low sugar” and “low fiber” diets couldn’t be used as a proxy for “low carbohydrate” diets, despite sugar and fiber both being carbohydrates. This suggests that many dieters don’t fully understand the nutritional composition of their chosen eating patterns.

The “diabetic diet” option provided no description to participants, yet many chose this category. Without knowing what constitutes a diabetic diet, people may have been following widely different eating patterns while believing they were on the same plan.

This classification confusion may partly explain why some dietary approaches showed no clear mental health effects—the categories may have been too broad or imprecise to capture meaningful patterns.

The Laboratory vs. Reality Gap

The study highlights a crucial disconnect between controlled research environments and real-world dieting experiences. Laboratory studies typically provide participants with carefully planned meals, nutrition education, and ongoing support—conditions that rarely exist for independent dieters.

In controlled settings, participants usually achieve their weight loss goals and maintain balanced nutrition throughout the study period. These ideal conditions may explain why laboratory research consistently shows mental health benefits from calorie restriction.

Real-world dieters face numerous challenges absent from research settings: unclear nutritional guidance, limited food preparation skills, financial constraints, social pressures, and lack of professional supervision. These factors can transform potentially beneficial dietary changes into sources of stress and nutritional inadequacy.

The Support System Difference

Another critical factor involves social and professional support systems. Research participants typically receive regular check-ins, educational materials, and professional guidance throughout their dietary interventions. Most independent dieters lack access to registered dietitians, psychologists, or other professionals who could help navigate the mental health challenges of restrictive eating.

This support gap may be particularly important for men, who research shows are less likely to seek help for both nutritional and mental health concerns. Without proper guidance, men attempting restrictive diets may be especially vulnerable to developing the depression symptoms documented in this study.

Clinical Implications

The findings have immediate implications for healthcare providers recommending dietary changes. The research suggests that simply telling patients to “eat less” or “cut carbs” without considering individual risk factors could inadvertently worsen mental health outcomes.

Healthcare professionals may need to screen for depression risk factors before recommending restrictive diets, particularly for male patients and those who are overweight. The study suggests that tailored dietary counseling based on sex and BMI could help prevent diet-induced depression.

Professor Sumantra Ray, commenting on the research, noted that the study “adds to the emerging evidence linking dietary patterns and mental health, raising important questions about whether restrictive diets which are low in nutrients considered beneficial for cognitive health, such as omega-3 fatty acids and vitamin B12, may precipitate depressive symptoms.”

Key Research Findings

The comprehensive analysis revealed several crucial insights:

• Calorie-restricted diets increased depression scores by 0.29 points overall
• Overweight individuals showed 0.46-0.61 point increases depending on diet type
• Men experienced higher depression symptoms across all three restrictive diet categories
• Nutrient-restricted diets particularly affected cognitive-emotional symptoms in men
• Self-reported diet classification showed concerning inaccuracies among participants
• Real-world dieting outcomes differed dramatically from controlled laboratory studies
• Weight cycling and failed weight loss may contribute to diet-induced depression

Looking Forward

The research opens new questions about how to balance physical health goals with mental health protection. While calorie restriction remains an important tool for managing obesity and related health conditions, the findings suggest that implementation methods need careful consideration.

Future studies should examine whether providing better nutritional education, mental health support, or gradual diet modifications could preserve the physical benefits of calorie restriction while minimizing depression risks. The researchers specifically called for intervention studies testing tailored dietary recommendations based on individual risk factors.

The study also highlights the need for more research simulating real-world dieting conditions rather than ideal laboratory environments. Understanding how dietary changes affect mental health under realistic conditions—including barriers, setbacks, and imperfect adherence—could lead to more effective and safer weight management strategies.

As obesity rates continue rising globally, finding ways to help people lose weight without triggering depression becomes increasingly critical for public health. This research suggests that the path forward may require more individualized, carefully supervised approaches rather than one-size-fits-all dietary recommendations.