Summary: New research links low-calorie diets with a slight increase in depressive symptoms, particularly among overweight individuals and men.
Those on calorie- or nutrient-restrictive diets scored higher on measures of emotional and physical distress than those not dieting.
Key Facts: Depression Risk: People on calorie-restrictive diets had higher PHQ-9 depression scores than non-dieters.
Obesity Link: Overweight and obese participants following restrictive diets experienced more pronounced depressive symptoms.
The findings also contradict those of previously published studies suggesting that low calorie diets improve depressive symptoms.
According to recent studies, low-calorie diets may be associated with a marginal rise in depressive symptoms, especially in men and overweight people. The extensive observational study examined depression scores and eating patterns in more than 28,000 U.S. S. adults.
On tests of emotional and physical distress, those following diets that restricted calories or nutrients performed worse than those who were not. These results imply that restrictive diets that are not monitored may have detrimental effects on mental health in practical situations.
Key Facts:.
Depression Risk: Those following calorie-restrictive diets scored higher on the PHQ-9 than those who were not on a diet.
Gender Differences: Compared to women, men on restrictive diets reported higher levels of emotional and physical symptoms.
Obesity Link: Those who were overweight or obese and were on restrictive diets had more severe symptoms of depression.
BMJ is the source.
Research published in the open access journal BMJ Nutrition Prevention and Health indicates that eating a low-calorie diet is associated with an increased risk of depressive symptoms.
The results imply that men and overweight people may be particularly susceptible to the negative effects of restrictive eating.
While an “unhealthy” diet that is dominated by ultra-processed foods, refined carbohydrates, saturated fats, processed meats, and sweets is generally linked to a higher risk of depression, the researchers explain that a “healthy” diet that is rich in minimally processed foods, fresh fruits and vegetables, whole grains, nuts, seeds, lean proteins, and fish is generally linked to a lower risk.
However, there are a variety of diets that people follow for health or medical reasons, such as those that limit calories or specific nutrients, and it’s unclear whether these other dietary patterns could be linked to an increased risk of depressive symptoms, they add.
They drew on 28,525 adult participants (14,329 women and 14,196 men) who had answered the Patient Health Questionnaire-9 (PHQ-9) for the severity of depressive symptoms as part of the nationally representative US National Health and Nutrition Examination Survey (NHANES) for the years 2007–18 in order to investigate this further.
All told, 7995 participants (29 percent) were healthy weight, 9470 (33 percent) were overweight, and 11060 (38 percent) were obese, while 2508 individuals (just under 8 percent) reported depressive symptoms.
In order to determine which of the nine diet options listed in all six cycles of NHANES they were on, participants were asked if they were on any specific diets for weight loss or other health-related reasons.
Dietary patterns were divided into four categories: (1) calorie-restrictive; (2) nutrient-restrictive (low in sugar, salt, fat/cholesterol, fiber, or carbohydrates); (3) established dietary patterns (such as those modified for diabetes); and (4) not on a diet.
While 8 percent of 2026 participants followed a calorie-restrictive diet, 3 percent followed a nutrient-restrictive diet, and 631 percent followed an established dietary pattern, the majority of participants (25,009, 87 percent) stated they were not on any particular diet.
A higher percentage of men (12,772; 90 percent) than women (12,237; 85 percent) reported not being on a diet when stratified by sex. While nutrient-restrictive and established dietary patterns were less frequently reported, with the highest percentage of established dietary pattern users among obese participants (359; 3 percent), calorie restriction was most frequently reported by obese participants (1247; 12 percent) and those who were overweight (594; 8 percent).
The PHQ-9 scores of individuals following calorie-restrictive diets were 0–29 points higher than those who were not following any particular diet.
PHQ-9 scores were higher for those who were overweight and on a calorie-restrictive diet: they were 0 points higher for those who were on a calorie-restrictive diet, and they were 0 points higher for those who were on a nutrient-restrictive diet.
Nutrient-restrictive diets were linked to higher somatic symptom scores (excessive distress and anxiety about physical symptoms), while calorie-restrictive diets were also linked to higher cognitive-affective symptom scores (a measure of the relationship between thoughts and feelings).
These scores also differed by sex: all three types of diet were linked to higher somatic symptom scores in men, while a nutrient-restrictive diet was linked to higher cognitive-affective symptom scores in men compared to women who were not on a diet.
Additionally, those who were obese and following a structured diet scored higher on somatic and cognitive-affective symptoms than people who were healthy and not on a diet.
Since this is an observational study, it is impossible to draw definitive conclusions regarding causality. The researchers speculate that respondents might not have correctly categorized their diets either.
The results also run counter to earlier research that claimed calorie-restricted diets alleviated depression symptoms.
The reason for this discrepancy, however, is that previous research was mostly randomised controlled trials (RCTs), in which participants followed carefully planned diets that ensured balanced nutrient intake, the researchers explain.
In contrast, real-world calorie-restricted diets and obesity frequently lead to physiological stress and nutritional deficiencies, especially in protein and important vitamins and minerals. These factors can worsen depressive symptomatology, including cognitive-affective symptoms. “”.
They indicate that failure to lose weight or weight cycling—losing weight and then regaining it—could be another reason.
The researchers explain the gender differences by pointing out that brain health depends on glucose and the fatty acid omega-3. They propose that diets low in fats (omega-3) or carbohydrates (glucose) may, in theory, impair brain function and aggravate cognitive-affective symptoms, particularly in men who require more nourishment.
“This study adds to the emerging evidence linking dietary patterns and mental health, raising important questions about whether restrictive diets that are low in nutrients considered beneficial for cognitive health, such as omega-3 fatty acids and vitamin B12, may precipitate depressive symptoms,” says Professor Sumantra Ray, Chief Scientist and Executive Director of the NNEdPro Global Institute for Food, Nutrition and Health, which co-owns BMJ Nutrition Prevention & Health with BMJ Group.
However, the effect sizes are small, and the findings’ generalizability is further constrained by additional statistical limitations. Continued research along this crucial line of inquiry requires more carefully planned studies that precisely measure dietary intake and reduce the effects of chance and confounding. “.”.
Concerning this research on depression and diet.
Written by Caroline White.
BMJ is the origin.
Contact: BMJ’s Caroline White.
Picture: Neuroscience News is credited with this picture.
