A large new study challenges the idea that eating fewer calories automatically benefits mental health. The research, published in BMJ Nutrition, Prevention & Health, analyzed data from more than 28,000 adults and found that those on calorie-restricted diets—especially men and people who are overweight—reported higher depressive symptoms than those not on such diets. This finding is based on data from multiple national health surveys and national nutrition programs.
Lead author, a psychiatrist and clinician-researcher at a renowned Toronto hospital and its university, urges caution with overly restrictive eating plans. He notes that balanced, sustainable dietary changes that meet nutritional needs and account for psychological well-being may help minimize mood-related risks.
Globally, depression remains a major public health concern, with rates rising significantly over recent decades. Data from BMJ Nutrition indicates major depression incidence climbed by about 50% between 1990 and 2017. For Thai public health officials and everyday readers alike, the study adds nuance to diet-and-mood discussions that often focus on weight loss alone. In Thailand, weight management campaigns are common in hospitals and public health messaging, but experts emphasize that how people eat matters as much as how little they eat.
The study examined six cycles of a national health and nutrition survey. Participants were categorized into four diet groups: calorie-restricted diets, nutrient-restricted diets (such as low sugar or low fat), established patterns like DASH or diabetic diets, and no specific diet. After adjusting for age, body mass index, income, and food security, only those on calorie-restricted diets showed a significant rise in depression scores.
Further analysis revealed that among overweight individuals, both calorie- and nutrient-restricted diets correlated with higher depression scores. In contrast, among individuals with healthy weight or obesity, these associations were not as clear. Among men, all dieting patterns were linked to more somatic (physical) symptoms, and nutrient-restricted diets also related to heightened cognitive-affective symptoms. The researchers suggest nutritional gaps from unbalanced restriction may disrupt energy, sleep, and concentration, particularly in men who often have higher nutrient needs.
This challenges earlier trials that suggested low-calorie diets could relieve depressive symptoms when guided by professionals. A postdoctoral researcher from a leading UK university explains that unsupervised or extreme dieting can create nutritional deficiencies and even worsen mood. “If weight loss is not achieved or if weight cycling occurs, mood improvements may not follow, and motivation can drop,” she notes.
The study also aligns with broader nutritional psychiatry findings: diets high in ultraprocessed foods link to more depressive symptoms, while Mediterranean-style patterns rich in whole foods, vegetables, and healthy fats associate with lower depression risk. These insights reinforce the value of diverse, minimally processed diets for mental well-being.
For Thailand, the implications are timely. As mental health gains visibility in policy and practice, authorities encourage weight management as part of chronic disease prevention. The research suggests that sustainable, balanced dietary changes—rather than extreme restriction—are essential for mental health, especially for those facing body-image concerns or chronic stress. A nutritionist from a major U.S. medical center reinforces pragmatic guidance: prioritize a plate with protein, complex carbohydrates, healthy fats, fiber, and fruits and vegetables; gradually adjust portions; and avoid strict deprivation.
Depression affects urban and rural communities in Thailand, where rapid shifts in dietary habits and social pressures influence eating behaviors. Fad diets and weight-loss trends, propelled by media and pop culture, can foster unbalanced approaches. The new findings advocate for moderation, professional advice, and culturally appropriate meal patterns that preserve taste, nutrition, and social eating traditions.
Looking ahead, Thailand-specific research is needed to account for local diets, genetics, and social contexts. Large, longitudinal studies focusing on rice-vegetable-fish-centric Thai dietary patterns would help clarify their mental health impacts alongside physical health outcomes.
Practical takeaways for Thai readers: resist one-size-fits-all, rapid-weight-loss schemes. Seek guidance from registered dietitians or healthcare professionals before starting any diet—especially extreme or restrictive ones. Embrace colorful, minimally processed meals that cover all food groups. In Thailand’s culinary culture, meals are social events that emphasize balance, seasonality, and community, a philosophy increasingly supported by scientific evidence for both mind and body.
In summary, aggressive calorie restriction may pose mental-health risks, particularly for men and those who are overweight. A steady, balanced approach to eating—guided by professionals and aligned with Thai culinary traditions—offers the safest path to healthier bodies and minds.