Many people think that cutting calories, skipping snacks, and opting for salads will help them lose weight and feel better. However, about eight percent of U.S. adults struggle with depression yearly, and recent findings indicate that dieting might worsen that issue.
A significant survey conducted in the U.S. shows a connection between calorie-restricted diets and elevated scores on the PHQ-9 depression questionnaire, particularly among men and individuals with higher body weight. This research was led by psychiatrist Dr. Gabriella Menniti at the University of Toronto.
Link between calories and mood
The study analyzed responses from 28,525 adults who discussed their eating habits and motivations throughout six rounds of the National Health and Nutrition Examination Survey. Among those, about two thousand participants, or eight percent, showed enough depressive symptoms to meet clinical thresholds.
Those on calorie-restricted diets had nearly a third of a point higher depression scores compared to similar individuals who were not dieting. Although the difference seems minor, it was consistent across various income, age, and ethnic groups.
Men who monitored their calorie intake reported worse symptoms than women, showing higher rates of fatigue and sleep issues. Additionally, overweight participants who reduced their carb or fat intake experienced steeper declines in mood than those who maintained their weight.
Men carry a different risk
Nutrition experts believe that biological factors in men may heighten their nutritional needs. Men typically need more protein, iron, and several B-vitamins to sustain lean muscle. When these nutrients are lacking, energy metabolism can slow, resulting in mood-related chemicals like serotonin potentially dropping, which may lead to irritability and a flat emotional state. The research team observed this trend even when accounting for factors like income, education, and physical activity.
“Diets low in carbohydrates or fats could theoretically impair brain function and worsen mood and cognitive symptoms, especially in men with higher nutritional demands,” Dr. Menniti pointed out.
Weight matters more than willpower
Extra body weight can sometimes hide nutrient deficiencies, as fat stores calories but not vitamins. Therefore, overweight dieters often reduce portions without considering food quality. This imbalance can lead to a situation where weight loss is minimal, but the levels of essential nutrients drop significantly, which could lower motivation and cause frustration.
In the survey, the correlation between calorie restriction and low mood was strongest among adults with a body mass index between 25 and 30. The researchers suggest that unmet expectations may amplify the emotional impact of dieting.
Mood swings and calorie cuts
The brain uses roughly twenty percent of the daily energy, relying heavily on glucose. A significant drop in blood sugar can impair focus within moments and heighten anxiety. Cutting carbohydrates to achieve weight loss may leave brain cells undernourished long before seeing any results on the scale. This lack of energy is often misinterpreted as laziness or lack of self-control rather than a biological warning signal.
Fats also play a crucial role. Omega-3 fatty acids are vital for building cell membranes and managing inflammation, and insufficient seafood consumption has been associated with mood disorders. While studies on supplements vary, those starting with lower omega-3 levels seem to benefit the most. This finding suggests that deficiency might be the primary factor affecting mood, rather than the dosage of supplements taken.
Micronutrients hide in plain sight
Vitamin B12 is key for processes producing dopamine and serotonin. Research indicates adults with low B12 levels tend to report higher depression scores, even after accounting for income and alcohol consumption. Similarly, recent NHANES data show men with low ferritin levels exhibit more symptoms of depression, as the lack of this nutrient can drain energy and motivation quickly.
Restrictive diets that minimize red meat, eggs, or fortified cereals can lead to deficiencies in these nutrients within weeks, and mood changes are often noticeable before any lab tests reflect them.
Balancing calories and mood
Dietitians typically recommend filling half your plate with fruits and vegetables, one-quarter with lean protein, and the remaining quarter with whole grains. This strategy ensures adequate fiber for gut health, amino acids for neurotransmitter production, and slow-releasing starches for stable blood sugar levels.
Including two servings of fatty fish weekly or a daily handful of walnuts can provide the necessary omega-3s without resorting to supplements. Foods rich in vitamin B12, like yogurt or fortified plant-based milks, can help fill common nutrient gaps for those avoiding meat.
For managing weight, experts suggest cutting no more than 500 calories from daily needs. A gradual approach helps maintain nutrient density and reduces cravings that might derail progress.
Cut calories gradually
Monitoring mood alongside meals can be as simple as joting a single word like “flat” or “energized” next to meal entries in a phone app. Patterns can emerge over the week that tell more than any nutrition label.
If low energy consistently follows days of consuming under 1,800 calories, that information can act as a warning sign. The solution may be adding a small amount of complex carbs instead of abandoning the diet entirely.
Mental health professionals often emphasize that food acts as information rather than just fuel. Sending the right message requires mindful adjustments rather than rigid restrictions.
Small, sustainable changes can yield quicker results than drastic diets. Both your mind and body will appreciate the differences.
The study appears in BMJ Nutrition, Prevention & Health.
