- A new cross-sectional study led by researchers from Toronto, Canada examined how dieting may affect depression symptoms.
- The researchers analyzed data from adult participants to determine whether certain types of diets can have negative implications for mental health.
- Their findings showed that participants who restricted calories were more likely to have more depressive symptoms.
The majority of adults in the United States –
One potential issue people trying to lose weight may come across is restricting calories or nutrient types too much.
The
However, people often go extreme when they start trying to lose weight and severely restrict their calorie count. Others will even focus on eating only one food group such as with the carnivore diet.
While losing weight can be important for some, it is also vital to do it in a healthy manner.
The study findings appear in BMJ Nutrition Prevention & Health.
Depression affects millions of people every year, and in the U.S., cases of depression are on the rise. According to 2020 data from the
The authors of the current study noted that research shows that eating healthy foods can help mental health, and that processed foods can harm it. However, the researchers say that more information is needed on calorie and nutrient restriction, a gap they wanted to close with this study.
The researchers used data from 28,525 adults who participated in both the National Health and Nutrition Examination Survey (
The study categorized participants into four groups:
- calorie-restricted diet (8%)
- nutrient-restricted diet (3%)
- established medical dietary pattern, such as the DASH diet (2%)
- not on any diet (87%).
The researchers compared how the participants responded to the PHQ-9 and considered factors such as body mass index (BMI) and biological sex.
The researchers found a connection between the diet category the participants were in and their depressive symptoms. Overall, 7.79% of the participants reported having depressive symptoms.
People in the calorie-restriction group had higher overall PHQ-9 scores — they had an increase of 0.29 points compared to the other groups.
The increase was more pronounced when considering only people with higher BMIs in the calorie-restriction group. Their PHQ-9 score was higher by an average of 0.46 points.
Even more concerning was an association found in overweight people in the nutrient-restriction group. While the nutrient-restriction group did not have a higher PHQ-9 score overall, when looking specifically at overweight people in this group, they had a higher PHQ-9 of 0.61 points.
The researchers also noticed some associations emerge depending on the biological sex of the participants. The researchers used the PHQ-9 to measure somatic symptoms which are physical symptoms related to psychiatric distress.
According to the study authors, “in biological men, all three dietary patterns were associated with higher somatic symptom scores.”
Men who were on a nutrient-restricted diet were also more likely to have an increase in cognitive-affective symptoms.
The study authors think these associations may be attributed to men having higher caloric needs and not getting their nutritional needs met through their food intake.
Amy Roethler, RDN, LD, a dietitian and nutritionist for Newport Healthcare’s PrairieCare program, who was not involved in this research, spoke about the study with Medical News Today.
“For many years, there has been suspicion that significant calorie restriction can lead to negative impacts on one’s mental health, specifically depressive symptoms,” Roethler said. ”This study certainly provides additional support to this theory.”
The dietitian noted that, from her experience working with patients that they tend not to focus as much on their nutrient intake but instead focus more on restricting their calories which is why this likely happens.
“In general, I find once individuals are able to make some changes to their eating habits, eating more fruits and vegetables, whole grains, healthy fats, and lean proteins, they find they start to feel better, which often leads to sustained changes,” she added.
Roethler also said she recommends that primary care providers who are working with patients trying to lose weight who also have a history of depression refer their patients to registered dieticians for guidance.
Timothy Frie, MS, CNE, a neuronutritionist and nutritional psychology researcher, also shared his thoughts about the study — in which he was not involved — with MNT.
“The finding that calorie restriction is associated with increased depressive symptoms – especially in men and people with elevated BMI – highlights that mental Health consequences may arise when dietary changes are made without adequate support, monitoring, or nutrient sufficiency,” said Frie.
Frie explained that calorie restriction can sometimes lead to people cutting out foods that the body needs for mood regulation:
“Cutting calories or entire food groups leads to deficits in B vitamins (especially B12, B6, and folate), iron, omega-3 fatty acids, and complex carbohydrates — all essential for neurochemical processes that regulate mood and emotions.”
On this note, the study authors hope to research specific nutritional deficits that may occur with dieting and what impact those deficits have on depressive symptoms.
