Following a low-calorie diet may be linked to a higher risk of depression, according to a new study published in BMJ Nutrition, Prevention & Health. The research suggests that men and people who are overweight might be particularly vulnerable to the emotional effects of restrictive eating patterns.
While healthy diets rich in whole foods like fruits, vegetables, whole grains, nuts, and lean proteins are generally linked to better mental health, the researchers wanted to know whether diets that restrict calories or certain nutrients—for reasons like weight loss or medical conditions—could be connected to depressive symptoms.
To investigate, researchers analyzed data from 28,525 adults in the U.S. National Health and Nutrition Examination Survey (NHANES) from 2007 to 2018. Participants completed a standard depression screening (PHQ-9), and provided information about their diets.
They were asked whether they were following a specific diet—such as calorie restriction, low fat or sugar, or a diet for conditions like diabetes—and their responses were grouped into four categories:
- Calorie-restrictive diets
- Nutrient-restrictive diets (low in fat, sugar, carbs, etc.)
- Medically-advised diets (like diabetic-friendly diets)
- No specific diet
Most people (87%) said they weren’t on any diet. About 8% reported following a low-calorie diet, 3% followed a nutrient-restricted diet, and 2% followed a medically advised eating pattern.
Depressive symptoms were more common in people on calorie-restrictive or nutrient-restrictive diets than in those not on any diet. People on calorie-restrictive diets had slightly higher PHQ-9 scores—on average, 0.29 points higher.
The effect was stronger among overweight individuals on a calorie-restricted diet, who had scores 0.46 points higher. Nutrient-restrictive diets were linked to even greater increases in depression scores, especially among overweight people (+0.61 points).
Men appeared to be more affected than women. Nutrient-restricted diets were linked to higher levels of cognitive-affective symptoms (feelings of sadness, hopelessness, and trouble concentrating) in men, while all types of restrictive diets were linked to greater physical symptoms (like fatigue and appetite changes).
In people with obesity, even medically advised diets were linked to higher depression scores, including both emotional and physical symptoms.
Though these results don’t prove that dieting causes depression, the researchers offer some explanations. In real life, calorie-restricted diets—especially when self-managed—can lead to poor nutrition.
Diets that lack protein, healthy fats like omega-3s, and key vitamins (like B12) may negatively affect brain function and mood. In contrast, clinical studies that found improvements in depression often involved well-balanced, closely monitored diet plans.
Weight loss struggles may also play a role. People who don’t see results from dieting, or who regain lost weight, may become discouraged or develop negative feelings about their health or self-image, further affecting mental wellbeing.
The authors also note that men may have higher nutritional requirements, making them more sensitive to deficiencies that affect brain function. For example, the brain relies heavily on glucose (from carbs) and omega-3 fatty acids (from fats), and diets that cut out these nutrients could increase the risk of depressive symptoms, especially in men.
Professor Sumantra Ray, Chief Scientist of the NNEdPro Global Institute, commented that the study raises important questions about how restrictive diets might impact mental health. He also cautioned that the effect sizes were small and that more research is needed to confirm these findings.
In short, while reducing calories might help with weight goals, it could come with emotional side effects—especially if the diet lacks important nutrients or is not balanced. These findings highlight the need for mindful, well-planned approaches to dieting, and for considering mental as well as physical health when making dietary choices.
If you care about mental health, please read studies about how dairy foods may influence depression risk, and 6 foods you can eat to improve mental health.
For more mental health information, please see recent studies about top foods to tame your stress, and Omega-3 fats may help reduce depression.
The research findings can be found in BMJ Nutrition, Prevention & Health
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