In a newly published analysis – based on national health data – a team of Canadian researchers have discovered that both calorie- and nutrient-restrictive diets could be hiding a link to elevated depressive symptoms. And that effect appears to be amplified in overweight individuals and biological men.
Quite simply, this new paper threatens to upend some popular opinions that restrictive eating patterns are universally beneficial for mental health. It also serves as a stark reminder that a one-size-fits-all approach to dietary guidance doesn’t really fit anyone.
Methodology
The new study, appearing in BMJ Nutrition, Prevention & Health, examined data from more than 28,000 U.S. adults who participated in the National Health and Nutrition Examination Survey (NHANES) between 2007 and 2018.
Survey participants completed both dietary assessments and the Patient Health Questionnaire-9 (PHQ-9), the standard tool used to evaluate depressive symptoms.
The findings suggest that those who followed calorie-restricted diets had, on average, a 0.29-point increase in depressive symptom scores compared to those who weren’t. For the overweight participants, the impact was more pronounced: a 0.46-point jump with calorie restriction, and a 0.61-point bump with nutrient-restricted diets.
Diet and Depression
Multiple studies have illustrated the mental health benefits of “healthy” diets – whether they focus on fruits, vegetables, whole grains, or lean proteins. But this new research explores the more nuanced reality of how we all eat. And why. In practice, restrictive diets can help curb caloric intake, they vary wildly in what they offer in terms of nutrition.
In practice, restrictive diets – especially those involving strict calorie or nutrient limitations – can lead to lower energy levels, poor sleep, and hampered cognitive function, all of which are somatic or cognitive-affective symptoms associated with depression.
Those Most At Risk
Biological men and individuals with higher body mass index (BMI) emerged as particularly vulnerable groups in this particular study.
Men who followed any type of restrictive diet reported higher somatic symptoms (such as fatigue and sleep disturbances). Those on nutrient-restrictive diets also suffered a 0.4-point jump in cognitive-affective symptoms, such as low mood and trouble concentrating.
The authors, working out of the University of Toronto, theorize that these effects could come from the higher nutritional requirements that men’s bodies demand. So, if a new diet cuts back dramatically on those calories, it can initiate a ripple effect that hinders physical and mental functioning.
On top of that, men tend to lean toward high-fat, high-sugar foods. As a result, they might find restrictive diets more psychologically taxing due to their preferences and beliefs around food.
For overweight participants, the researchers failed to turn up any of the mood benefits they expected. On the contrary, their depressive symptoms got worse. The authors blame nutritional deficiencies or the stress of unsuccessful weight loss efforts in uncontrolled, real-life settings.
Implications for Public Health and Clinical Practice
The authors encourage healthcare providers to look at individual factors when offering dietary advice to their patients. They also stress the need for a broader investigation, including research that replicates real-world eating patterns. The resulting data could lead to more effective, tailored nutrition strategies that boost physical and mental health outcomes.
Ultimately, the findings point to an important consideration often overlooked in the dietary debate: the potential high psychological cost of restrictive eating.
Further Reading
Prediction Of Adolescent Suicidal Events By Residual Depressive Symptoms
