
Most common form of weight-loss diet can trigger depression - new study shows
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PEOPLE ON THE DIETS EXPERIENCE LOW MOOD, LOW ENERGY AND SLEEP DISTURBANCES 23:30, 03 Jun 2025 Following a low-calorie diet could increase the risk of developing symptoms of depression, a
study suggests. The effects of calorie restriction on mood were more pronounced in men and overweight people, researchers said. The findings contrast previous studies which claim low-calorie
diets improve depressive symptoms. However, researchers argue prior trials included tailored and balanced diet programmes that may not be the same as what people realistically follow in
everyday life. For the study, published in BMJ Nutrition Prevention and Health, researchers in Canada used data from the 28,525 people who took part in the US National Health and Nutrition
Examination Survey (NHANES) and had completed a health questionnaire relating to depressive symptoms, which gave them a score based on severity. Of the total, 14,329 were women and 14,196
were men. A little under 8% had reported depressive symptoms, while 33% were overweight and 38% were obese. The majority of the group (87%) said they were not on a specific diet, while 2,206
were restricting calories. Some 859 were on a "nutrient-restrictive" diet, low in fat, sugar, salt, fibre or carbohydrate, and 631 were on diets tailored for the likes of
diabetes. Researchers found low-calorie diets were more common among obese patients and those who were overweight. Questionnaire scores for depressive symptoms, such as a low mood, low
energy and sleep disturbances, were higher among those restricting calories compared to those who reported not being on a diet at all. The scores were also higher among overweight people
following low-calorie diets. Article continues below Researchers said: "Numerous studies have consistently focused on 'healthy' versus 'unhealthy' diets. "They
have shown that 'healthy' diets rich in minimally processed foods, fresh fruits and vegetables, whole grains, nuts, seeds, lean proteins and fish have been linked to a lower risk
of depression. "In contrast, an 'unhealthy' diet dominated by ultra-processed foods, refined carbohydrates, saturated fats, processed meats and sweets is associated with an
increased risk of depressive symptoms. Therefore, individuals must adopt a perfectly healthy dietary pattern to reduce the risk of depressive symptoms. This dichotomy fails to capture the
complexity of real-world eating habits." Restricting calories can lead to deficiencies in protein, vitamins and minerals, researchers suggest, which puts the body under stress. The
findings also contradict previous studies showing low-calorie diets improve depressive symptoms. Researchers highlight that these studies were controlled trials, with those taking part
following carefully designed and balanced diets. The team said a focus on "idealised diets" can "overlook the diversity of dietary patterns", adding: "In contrast,
real-life calorie-restricted diets and obesity often result in nutritional deficiencies, particularly in protein, essential vitamins and minerals, and induce physiological stress, which can
exacerbate depressive symptomatology including cognitive-affective symptoms." Researchers stressed the study has a number of limitations, but gives an insight to how diets recommended
by healthcare professionals should be considered for risk factors for depression, especially in men and obese patients. Article continues below Professor Sumantra Ray, chief scientist and
executive director of the NNEdPro Global Institute for Food, Nutrition and Health, which co-owns BMJ Nutrition Prevention and Health with BMJ Group, added: "This study adds to the
emerging evidence linking dietary patterns and mental health, raising important questions about whether restrictive diets which are low in nutrients considered beneficial for cognitive
health, such as omega-3 fatty acids and vitamin B12, may precipitate depressive symptoms. "But the effect sizes are small, with further statistical limitations limiting the
generalisability of the findings. Further well designed studies that accurately capture dietary intake and minimise the impact of chance and confounding are needed to continue this important
line of inquiry."