A major new study has cast doubt on the widely held belief that calorie restriction is inherently beneficial for mental health, with fresh evidence suggesting that cutting calories too far may actually increase the risk of depressive symptoms. The research, published in the journal BMJ Nutrition, Prevention & Health, analyzed data from over 28,000 adults and found that individuals following calorie-restricted diets—especially men and those who are overweight—were more likely to report heightened symptoms of depression compared to those not on such diets (CNN, BMJ Nutrition).
This study’s lead author, a psychiatrist and clinician-researcher at St. Michael’s Hospital and the University of Toronto, cautioned: “The findings suggest caution with overly restrictive or unbalanced diets, particularly for people already experiencing weight-related stress or challenges. Opting for balanced, sustainable dietary changes that meet nutritional needs and consider individual psychological impacts may help minimize potential negative effects on mood.”
The global relevance of these findings cannot be understated, as depression rates have been rising sharply worldwide. Between 1990 and 2017, the incidence of major depression climbed by roughly 50% (BMJ Nutrition). Diet has long been recognized as a modifiable factor influencing physical health, but only in recent years has its impact on mental wellness come under scientific scrutiny. For Thais, where weight loss diets and fad eating patterns are commonly discussed both in the media and among health professionals, these findings have strong implications for public health messaging and individual choices.
The study utilized baseline data from six cycles of the National Health and Nutrition Examination Survey, with participants reporting their diet type and symptoms associated with depression. Four dietary categories were compared: calorie-restricted diets, nutrient-restricted diets (such as low sugar or low fat), established dietary patterns like DASH or diabetic diets, and no diet at all. Only those on calorie-restricted diets showed a statistically significant increase in depression scores—even after adjusting for factors such as age, BMI, income, and food security.
Digging deeper, the researchers found that among overweight individuals, both calorie- and nutrient-restricted diets were correlated with higher depression scores, while such associations were not evident in healthy-weight or obese groups. Strikingly, for biological men, all three dieting patterns (including established ones) were linked to higher physical (somatic) symptom scores, and nutrient-restrictive diets also raised cognitive-affective depression symptoms. The underlying cause, according to the research team, may relate to the nutritional deficiencies often triggered by unbalanced calorie restriction, which can disrupt energy balance, sleep, and concentrations—especially in those with higher biological nutritional needs, such as men (BMJ Nutrition).
Notably, these findings run counter to traditional beliefs and previous research. Earlier randomized controlled trials (RCTs) suggested that low-calorie diets could reduce depressive symptoms, particularly when supervised by medical professionals, with participants receiving proper guidance to avoid deficiencies. As a postdoctoral researcher at King’s College London explained, unsupervised or extreme dieting, which can produce nutritional gaps, may not have the same benefits or might even exert harmful psychological effects. “Embarking on a calorie restricted diet without experiencing weight loss, or experiencing ‘weight cycling’, might not produce improvements in depression, and on top of that may be frustrating or disheartening,” she pointed out (CNN, People).
Further illustrating the complexity, people with diets high in ultraprocessed foods—such as refined carbs, sweets, and processed meats—also demonstrated higher rates of depressive symptoms. Conversely, those consuming a Mediterranean-style diet, rich in whole foods, vegetables, and healthy fats, generally had a lower risk of depression. This finding is in line with established nutritional psychiatry literature, which highlights the positive mental health effects of diverse, minimally processed diets (New York Post).
For Thailand, these nuanced insights come at a time of increasing focus on mental health and wellness, both among policy makers and the general public. In recent years, the Ministry of Public Health and various hospital departments have promoted weight management as part of chronic disease prevention. However, the new study indicates that the way people pursue healthy eating is just as important as the fact of eating less. Extreme dietary restriction—whether unsupervised fasting, skipping multiple meals, or rapidly cutting out food groups—could inadvertently harm psychological well-being, especially for those already struggling with body image or chronic stress.
A nutritionist from a US medical center, interviewed by CNN, recommends small, sustainable changes: “Does your plate have a protein, carbohydrate, healthy fat, and some fiber and nutrients through fruits and vegetables? Try prioritizing adding in the nutrition you need first, then see whether there are elements you don’t need anymore. Perhaps if you eat from all of your food groups and slow your meals down, you’ll realize you don’t need to grab a second helping or you won’t feel the same urgency to grab a sweet treat after.”
Depression in Thailand is already a public health concern, particularly in urban areas where social pressures and shifting dietary habits are on the rise (Wikipedia). Fad diets and rapid weight loss trends, influenced by both Western and Asian pop culture standards, have contributed to a diet culture where calorie counting and restriction are seen as fast paths to self-improvement. However, these new findings suggest that a more moderate, balanced approach, and professional guidance, are necessary to avoid unintended negative impacts on mood and overall well-being.
Looking further into the future, more research—especially well-controlled, Thailand-specific studies—will be important to distinguish the unique variables at play in local eating habits, genetic backgrounds, and social contexts. While the US-based NHANES data offers extensive generalizability, there remains an urgent need for large, longitudinal studies evaluating traditional Thai dietary patterns (such as rice-vegetable-fish-centric diets) and their impact on both physical and mental health.
What should Thai readers take away from this research? First and foremost, professionals advise against the lure of one-size-fits-all rapid weight loss solutions. Consulting with registered dietitians, nutritionists, or healthcare specialists before embarking on any diet—especially an extreme or restrictive one—is strongly recommended. Focusing on a colorful, minimally processed, balanced meal is likely to be safer and more beneficial for the mind as well as the body. This is particularly poignant in Thailand, where culinary tradition emphasizes variety, seasonal produce, and communal meals—wisdom that modern dietary science increasingly validates.
In summary, calorie-restrictive diets may carry unseen mental health risks, particularly for men and those already overweight. Instead of aiming for the fastest dietary fix, Thai readers would do well to heed the time-tested culinary principles of moderation and balance, and to seek professional advice adapted to their personal physiological and psychological needs. Ultimately, healthier bodies and happier minds go hand-in-hand with sustainable, thoughtfully guided nutritional choices (BMJ Nutrition, CNN, People, New York Post).