A study published Tuesday in BMJ Nutrition, Prevention & Health suggests that restricting calories too severely may be associated with worsening symptoms of depression.
Researchers analyzed data from more than 28,000 adults who participated in the National Health and Nutrition Examination Survey (NHANES). The study examined participants’ dietary habits alongside their reported symptoms of depression.
According to the findings, people who followed calorie-restrictive diets — especially men and those with a body mass index (BMI) in the overweight range — were more likely to report higher levels of depressive symptoms.
Diet quality also played a significant role. Participants who consumed more ultraprocessed foods, refined carbohydrates, saturated fats, processed meats, and sweets tended to experience greater symptoms of depression. In contrast, those who followed a Mediterranean-style diet, rich in fruits, vegetables, whole grains, and healthy fats, generally reported better mental health outcomes.
“The findings suggest caution against overly restrictive or nutritionally unbalanced diets, particularly for individuals already dealing with weight-related stress or mental health challenges,” said Dr. Venkat Bhat, lead author of the study, psychiatrist, and director of the Interventional Psychiatry Program at St. Michael’s Hospital and the University of Toronto.
Instead of drastic calorie cuts, Bhat recommends choosing balanced, sustainable dietary changes that support nutritional needs while taking into account the psychological effects of dieting.
A Different Take from Earlier Research
The study’s authors note, however, that the research has limitations. Because of its observational design, the study can only highlight an association between calorie restriction and depressive symptoms — it cannot prove a direct cause-and-effect relationship.
Additionally, the study relied on participants’ self-reported dietary patterns, which leaves room for inaccuracies, according to Dr. Kary Woodruff, an associate professor and director of the Coordinated Master’s Program in Nutrition and Integrated Physiology at the University of Utah, who was not involved in the study.
Still, the findings add to growing evidence suggesting that extreme dieting and poor diet quality may negatively impact mental well-being — and that a balanced, nutrient-rich approach may be the healthier, more sustainable path for both body and mind.
“I could think I’m on a calorie-restricted diet when in fact I may be in a calorie surplus — there’s no way to verify participants’ calorie-restriction status,” Woodruff noted.
While the study was large and adjusted for multiple factors that could influence the outcomes, its findings diverge from some earlier research on the relationship between calorie restriction and depression, according to Bhat.
“Other studies have actually found that calorie-restricted diets can reduce depressive symptoms,” said Dr. Johanna Keeler, a postdoctoral researcher at King’s College London, who was not involved in the new study. Keeler coauthored a 2023 study that suggested calorie restriction, when carefully managed, may help improve mood in certain cases.
A key distinction, Keeler pointed out, is that previous research often involved supervised dietary interventions, where participants followed calorie-restricted plans under the guidance of healthcare professionals. “These findings might reflect that unsupervised dieting, which can easily lead to nutritional deficiencies, may worsen depressive symptoms,” she said.
Both Bhat and Keeler agree that more high-quality research — especially randomized controlled trials — is needed to better understand how dieting behaviors influence mental health over time.
When Calorie Restriction Could Worsen Depression
Experts say there are several possible reasons why calorie restriction, particularly when done without medical supervision, might negatively affect mental health.
For one, extreme calorie cutting can lead to deficiencies in essential nutrients — such as omega-3 fatty acids, B vitamins, iron, and magnesium — all of which play critical roles in mood regulation and brain health. Without these nutrients, people may become more vulnerable to depressive symptoms.
Additionally, strict dieting can increase stress, anxiety, and a preoccupation with food, which might exacerbate underlying mental health issues, especially for those already struggling with body image concerns or weight-related stress.
“The psychological burden of restrictive eating patterns, coupled with possible biological effects from insufficient nutrition, may explain why some individuals experience a decline in mood,” Bhat explained.
More research, especially randomized controlled trials, will be necessary to fully understand how different dieting approaches impact mental health, Bhat emphasized.
When Restriction Might Worsen Depression
There are several reasons why the calorie restriction observed in the recent study may be linked to poorer mental health outcomes.
While previous research — including Keeler’s — has shown that low-calorie diets can reduce depressive symptoms among people with overweight or obesity, those benefits may be tied to successful weight loss. According to Keeler, improvements in depression symptoms in those cases might stem from physiological changes, enhanced physical mobility, or even more positive social interactions following weight loss.
“Embarking on a calorie-restricted diet without actually experiencing weight loss — or experiencing ‘weight cycling’ — may not deliver the same mental health benefits. In fact, it could become frustrating and emotionally draining, potentially increasing depressive symptoms,” Keeler explained in an email.
Calorie restriction that is too extreme or nutritionally inadequate may also disrupt normal physical processes, she added. Fatigue, poor sleep, and difficulty concentrating can all result from insufficient nutrient intake.
According to Woodruff, rigid or unbalanced dieting behaviors have also been linked to increased anxiety and a greater risk for disordered eating.
“The key is to look at what — and how much — is being restricted,” Woodruff said. “Following a healthful eating pattern that includes mild to moderate caloric restriction may help improve mood and reduce depressive symptoms. But extreme approaches can seriously harm mental, emotional, and physical health.”
Finding the Right Balance
The takeaway? There’s no one-size-fits-all approach to dieting — and how individuals respond to calorie restriction can vary widely. Bhat stressed the importance of personalized dietary guidance that takes both mental and physical health into account.
With so much conflicting nutrition advice in the public sphere, Keeler recommends consulting with a healthcare provider or registered dietitian before making major dietary changes, especially when weight loss is the goal.
Even for those hoping to shed pounds, a heavily restrictive diet may not be the most effective — or sustainable — path, said Natalie Mokari, a registered dietitian based in Charlotte, North Carolina.
“Start by looking at your plate,” Mokari said. “Do you have a source of protein, a carbohydrate, a healthy fat, and some fiber or micronutrients from fruits and vegetables?”
Her advice is to focus first on what to include, rather than what to cut out. By prioritizing nutrient-dense foods, balanced portions, and slower eating habits, individuals may naturally eat less — without feeling deprived.
“You may find that when your body gets what it needs, you don’t crave as much of what it doesn’t,” she added.
Ultimately, experts agree that the goal shouldn’t be short-term calorie cuts, but rather long-term improvements in diet quality and overall well-being.
“Regardless of weight loss, improving dietary quality can have a significant positive impact on both physical and mental health,” Woodruff said. “Working with a registered dietitian can help you define what a truly nourishing, sustainable diet looks like for you.”