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Patients with obesity who adopt a low-calorie diet need to know the risks that come with it, particularly the chances for anxiety and symptoms of depression.

A recent study looks at low-calorie diets and the effect they can have on a person’s mental and emotional state, particularly as it relates to men and people with a higher BMI.

The cross-sectional study included 28,525 adults, of whom 7.79% self-reported depressive symptoms.

It acknowledges that some people undergo restrictive diets for health reasons and it’s an area that remains understudied.

“Men who follow a calorie-restricted diet had higher somatic symptom scores compared with women not on a diet,” according to the study, which was published in the journal BMJ Nutrition, Prevention & Health in June.

The authors said the study showed no significant association between “other dietary patterns and depressive symptoms. We also found no significant association between consuming a nutrient-rich diet and depressive symptoms.”

Scientists and health professionals have long emphasized the correlation between a healthy diet, rich in fruits and vegetables, lean meat, and fish, and better emotional wellbeing and cognitive function.

According to the study, calorie-strictive diets “were associated with higher depressive symptom scores, which contrasts with the findings of earlier controlled studies.” 

Researchers said future studies that simulate real-world dieting are important and should address how nutritional deficiencies may increase depressive symptoms.

Joe Esposito has seen similar symptoms in some of his patients.

Esposito is host of the nationally syndicated radio show, “The Dr. Joe Show” and is board-certified in chiropractic, nonsurgical orthopedics and is double board certified in nutrition.

He estimates that between 30% and 50% of his patients on low-calorie diets experience anxiety or depressive feelings.

“Many times, when people have a low-calorie diet they’re not getting enough nutrients as well,” he said. “You can have high-nutrient, low-calorie foods, but most people eat low-nutrient, low-calorie foods. So we’ve got to get those nutrients levels into the body if we’re going to do something like a low-calorie diet. We have to make sure you are eating high-quality foods along with taking quality supplements.”

Without supplements, he said, the body can survive but it won’t thrive.

“We see a lot of this with people taking GLP-agonists” such as Ozempic, which can lower blood-sugar levels and also depress the appetite.

Several healthcare professionals say, while the study is a good start, it opens the door for more research on the topic. They emphasize that it’s not clear if the people interviewed already had issues with anxiety or depressive symptoms.

“So one aspect is really the whole process of going through a calorie restricted or a diet that restricts certain sources of calories such as carbohydrates and that obviously can cause some stress to individuals in the best of times,” said Sumantra Ray, founding chair, chief scientist and executive director of the NNEdPro Global Institute for Food, Nutrition and Health in Cambridge, England. Ray is a licensed medical doctor and nutritionist.

He said what’s noted in this study is that there are a fairly large number of individuals, mostly men, who demonstrate that their self-reported depressive symptoms are a little bit more in the lower calorie group.

“It’s difficult to see whether it is a result of bias or confounding, when a cause-and-effect relationship may seem to exist when it really doesn’t,” said Ray, a leading nutrition expert and co-founder chair of BMJ Nutrition, Prevention and Health.

“However, another aspect of this study is the possibility that low-calorie diets may lead to an unintended lack of nutrients leading to possible deficiencies in essential nutrients which may in turn be linked with mental health risks.”

Either way, those on calorie restricted diets need to be supported by qualified healthcare professionals trained in nutrition. “And this study also gives researchers further direction in well-designed future studies that need to be conducted to elucidate the important relationships between food, mood, and mental health,” Ray said.