- A study of over 28,000 people found calorie restriction linked to more depressive symptoms, particularly in men and those with obesity
- Restrictive diets in real life may lead to nutrient deficiencies and physiological stress
- Researchers urge caution and call for balanced dietary guidance based on real-world eating habits
A new study has found that cutting calories may increase the risk of depressive symptoms, particularly among men and people living with overweight or obesity.
Published in BMJ Nutrition, Prevention & Health, the Canadian study analysed data from 28,525 adults who took part in the US National Health and Nutrition Examination Survey. Participants completed a mental health questionnaire measuring symptoms such as low mood, fatigue, and poor sleep.
The researchers found that those following low-calorie diets scored higher for depressive symptoms than those who were not dieting at all.
The effect was more noticeable among men and people classified as overweight or obese.
Around 8 per cent of participants reported experiencing depressive symptoms, while over 70 per cent were either overweight or obese.
Low-calorie diets were more common among people with obesity and those attempting to lose weight. However, the researchers suggested that these self-imposed dietary restrictions could lead to nutritional deficiencies – particularly in protein, vitamins, and minerals – putting the body under stress and worsening mental wellbeing.
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Previous studies have suggested that calorie-restricted diets might help improve mood, but these often involved carefully planned, nutritionally balanced interventions.
The current research challenges those findings, noting that real-world dieting often lacks nutritional balance and may not offer the same mental health benefits.
The study authors emphasised the difference between healthy and unhealthy diets. Diets rich in whole foods – such as fruits, vegetables, whole grains, nuts, and lean protein – have been linked to a reduced risk of depression. In contrast, diets high in ultra-processed foods and refined carbohydrates have been associated with a higher risk.
Professor Sumantra Ray, executive director of the NNEdPro Global Institute for Food, Nutrition and Health, commented on the study: “This adds to the growing body of evidence linking diet and mental health.
“Restrictive diets low in nutrients important for cognitive function, such as omega-3 and vitamin B12, may contribute to depressive symptoms. However, further well-designed studies are needed to better understand these relationships.”
While the study has limitations and cannot prove direct causation, it raises important questions for healthcare professionals when advising on weight loss or dietary changes – particularly for those already vulnerable to mental health challenges.
