A recent study reveals a potential link between low-calorie diets and increased depressive symptoms, particularly affecting men and overweight individuals. The research, analyzing data from thousands of adults, found that calorie-restrictive diets correlate with higher cognitive-affective symptom scores. Experts emphasize the importance of balanced nutrient intake, including glucose and omega-3 fatty acids, for optimal brain health and mental well-being.
Feeling the blues lately? It might be time to look beyond your emotions. This time, look into your plate. What you eat, or more specifically, how little you eat, could be impacting your mental health. Yes, you read that right! A recent study found that cutting back on calories may increase the risk of depressive symptoms.
According to a new study published in BMJ Nutrition Prevention & Health, following a low-calorie diet is linked to a heightened risk of depressive symptoms.
What is a healthy diet
A ‘healthy’ diet incorporates lots of vegetables, fruits, whole grains, nuts, seeds, lean proteins, and fish. The Mediterranean diet is considered one of the best diets in the world for its health benefits. This diet consists of fruits, vegetables, whole grains, legumes, nuts and seeds, and heart-healthy fats like olive oil.
Diet and mental health
What you eat has a significant impact on both your physical and mental health. While people always focus on the impact of diet on physical health, mental wellness often takes a backseat. The recent research has now shed light on this aspect. The study suggests that a low-calorie diet is linked to poor mental health, and men and individuals who are overweight are more vulnerable to these effects.
The researchers found that a healthy diet is linked to a lower risk of depression, while an ‘unhealthy’ diet (ultra-processed foods, refined carbs, saturated fats, processed meats, and sweets) is generally associated with a heightened risk.
Today, people follow various types of diets for health or medical reasons, and some may be calorie-restrictive or nutrient-lacking.
The study
To understand the effects of diet on mental health, the researchers analyzed data from 28,525 adults (14,329 women and 14,196 men) who participated in the National Health and Nutrition Examination Survey (NHANES) between 2007 and 2018 and completed the Patient Health Questionnaire-9 (PHQ-9), a widely used depression screening tool. In total, 2,508 participants (just under 8%) reported experiencing depressive symptoms. About 29% (7995) of participants had a healthy weight, 33% were overweight, and 38% were classified as obese.
The participants were then categorized based on their diets. The categories were:
- calorie-restrictive
- nutrient-restrictive (low in fat/cholesterol, sugar, salt, fibre, or carbs)
- established dietary patterns (adapted for diabetes, for example)
- not on a diet.
Most of them weren’t on any specific diet, while 8% followed a calorie-restrictive diet. A3% were on a nutrient-restrictive diet, and 2% had an established dietary pattern.
A greater proportion of men (12,772; 90%) weren’t on a diet compared to the women (12,237; 85%). The obese participants (1247;12%) and those overweight (594; 8%) were on a calorie deficit.
The findings
They found that calorie-restrictive diets were linked with higher cognitive-affective symptom scores (measure of the relationship between thoughts and feelings) while nutrient-restrictive diets were associated with higher somatic symptom scores (excessive distress and anxiety about physical symptoms). Men were especially vulnerable. Those on nutrient-restrictive diets experienced more cognitive-affective symptoms than women on no diet. All three types of restrictive diets were associated with higher somatic symptoms in men.
The findings of this study contradict those of previous ones, which suggested low-calorie diets improve depressive symptoms. “This discrepancy may arise because prior studies were primarily randomised controlled trials (RCTs) where participants adhered to carefully designed diets ensuring balanced nutrient intake. In contrast, real-life calorie-restricted diets and obesity often result in nutritional deficiencies (particularly in protein, essential vitamins/minerals) and induce physiological stress, which can exacerbate depressive symptomatology including cognitive-affective symptoms,” the researchers explained.
What are the experts saying
The researchers emphasized that glucose and the fatty acid omega-3 are essential for brain health. “Diets low in carbohydrates (glucose) or fats (omega-3s) may theoretically worsen brain function and exacerbate cognitive-affective symptoms, especially in men with greater nutritional needs,” the researchers said.
“This 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. But the effect sizes are small, with further statistical limitations limiting the generalisability of the findings. Further well-designed studies that accurately capture dietary intake and minimise the impact of chance and confounding are needed to continue this important line of inquiry,” Professor Sumantra Ray, chief scientist, said in a statement.
