More than 70% of U.S. adults are overweight or obese. To lose weight, people often change their diet or take medication. The National Institutes of Health (NIH) recommends lowering daily calories by 500 to 1,000 to lose 1–2 pounds per week. Cutting sugary drinks and making small food swaps can help.
Risks of Extreme Calorie and Nutrient Restriction
Some dieters go to extremes, cutting calories too much or eating from only one food group. These practices can harm physical and mental health. A new study in BMJ Nutrition Prevention & Health examined how calorie and nutrient restriction affect depression.
How the Study Was Conducted
Researchers used data from 28,525 adults in the National Health and Nutrition Examination Survey (NHANES) and their Patient Health Questionnaire-9 (PHQ-9) scores. Participants fell into four groups:
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Calorie-restricted diet (8%)
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Nutrient-restricted diet (3%)
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Established medical diets (e.g., DASH diet) (2%)
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No diet (87%)
The team compared PHQ-9 scores—an established measure of depressive symptoms—while controlling for factors like body mass index (BMI) and sex.
Key Findings on Depressive Symptoms
Overall Depression Rate: 7.79% of all participants reported depressive symptoms.
Calorie Restriction: Those on low-calorie diets scored 0.29 points higher on the PHQ-9 than non-dieters. Overweight dieters in this group scored 0.46 points higher.
Nutrient Restriction: Though overall scores did not rise, overweight participants in the nutrient-restricted group scored 0.61 points higher.
Men Face Higher Mental Health Risks
The study found that men on any of the three restrictive diets had higher somatic symptom scores (physical signs of depression). Men on nutrient-restricted plans also showed more cognitive-affective symptoms. Researchers suggest that higher male calorie needs may leave men short of essential nutrients when they diet.
Expert Commentary on Diet and Mental Health
Amy Roethler, RD, LP, dietitian at PrairieCare, noted that severe calorie cuts are long suspected to worsen mood. She emphasized the importance of balanced diets rich in fruits, vegetables, whole grains, healthy fats, and lean protein. Roethler advises doctors to refer weight-loss patients with depression to registered dietitians.
Neuronutritionist Timothy Frie, MS, CNE, highlighted how dieting without proper guidance can cause deficiencies in B vitamins, iron, omega-3s, and complex carbs—nutrients critical for mood regulation. He urged close monitoring of mental health during dietary changes.
Implications for Future Research and Care
The authors plan to explore which specific nutrient shortages drive the link between dieting and depression. Their goal is to guide safer weight-loss strategies that protect both physical and mental health.
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