Dietary tracking is a common tool for aiding weight loss and improving health outcomes, and many structured diets are promoted for long-term wellness. However, the restriction involved in such diets may also lead to mental rigidness or run the risk of nutrient deficiency that could impact mood and psychological state. Thus, a new study of more than 28,000 Americans sought to investigate: does dietary restriction come with added risks for depression?
Indeed, the researchers reported higher depression scores among individuals who engaged in dieting relative to those who did not.1 The findings made waves in the popular press — but do they hold up to scrutiny? Before you reconsider your nutrition goals, it’s worth digging a bit deeper into the data: what does this study really show, how strong is the link, and what can we learn?
Efficacy vs. effectiveness
The notion that diet may impact mental health certainly isn’t new. Several randomized controlled trials (RCTs) have evaluated such a relationship and have generally shown that caloric restriction — especially when paired with behavioral therapy, physical activity, or long-term adherence — tends to reduce symptoms of depression.2
Yet as the authors of this recent study point out, such RCTs are only capable of assessing efficacy — how well an intervention works under ideal, controlled conditions, such as when participants are monitored for diet adherence and receive regular professional support. They are not, however, designed to assess effectiveness — how well an intervention works under real-world conditions without such strict control. When people try to diet on their own, without coaching, in the context of daily stressors, inconsistent routines, and variable support systems, the results can look very different from those reported in clinical trials. In other words, an intervention that is efficacious might not necessarily be effective, but the latter is what matters when it comes to practical health implications.
Potential detriments of restricting?
To dig more deeply into the effectiveness question, researchers Menniti et al. turned to observational data from the National Health and Nutrition Examination Survey, or NHANES, a large-scale dataset from a representative sample of the U.S. population. Participants were divided into four groups based on their dietary data: 1) those who reported no nutritional restrictions whatsoever (n=25,009); 2) those who reported actively counting calories (i.e., calorie restriction, or CR; n=2,026); 3) those focused on limiting specific foods or macronutrients (i.e., dietary restriction, or DR; n=859); and 4) those who followed what the researchers called “established dietary patterns” — think Mediterranean diet, Dietary Approaches to Stop Hypertension (DASH), or other structured approaches (n=631).
For each of these groups, the authors also assessed depression scores using the Patient Health Questionnaire 9 (PHQ-9), a well-validated questionnaire that asks about symptoms like feeling down, having trouble sleeping, changes in appetite, and difficulty concentrating. The PHQ-9 is scored on a scale of 0-27, with a higher score indicating more severe depressive symptoms. Importantly, because depression and tendency to engage in dieting are both influenced by numerous other factors such as relationship status or chronic health conditions, the authors adjusted their statistical models for various potential confounding variables, including age, sex, race, education level, marital status, income, smoking, drinking habits, BMI, food security, diabetes, and hypertension.
Results revealed that participants utilizing a CR approach were more depressed than participants who did not engage in any form of dieting, with an average increase in PHQ-9 score of 0.29 points relative to the non-diet group (95% CI: 0.06–0.52) after adjusting for covariates. The DR group and “established diet” group also exhibited a trend toward higher depressive scores, but these differences did not achieve statistical significance, perhaps due to the relatively low numbers of participants in these groups.
These data suggest that, in a real-world setting, restricting calories may negatively impact mental health, in contrast to what has previously been observed in controlled trial settings. News outlets were quick to spread the bad news with headlines like “Your diet is making you depressed, according to science”3 and “Cutting calories can make you depressed.”4
Reality check
So, should we start questioning everything we know about nutrition and mental health? Not so fast.
Despite Menniti et al.’s argument that RCTs could not evaluate real-world effects of dieting on depression, the fact is that this recent study was even less capable of evaluating those effects than earlier research. As a strictly observational study, this work was incapable of testing any “effects” at all — real-world or otherwise — as such analyses can only identify correlations between variables, not their cause-and-effect relationships. To make matters worse, this analysis was based on cross-sectional data, representing a single snapshot in time, so we don’t even have any insight as to how diets and depression scores might have changed over time — or indeed, whether differences in depression scores preceded the adoption of CR.
Consider this alternative explanation: what if people who are already struggling with depression are more likely to turn to dietary restriction? This isn’t far-fetched. Depression often involves feelings of low self-worth, loss of control, and a desperate search for something — anything — that might help. Restricting calories or following rigid dietary rules can provide a sense of control and accomplishment, at least temporarily. In other words, depression might be driving the dieting behavior, not the other way around.
Even if we assume that dieting preceded higher depression scores, we need to take a critical look at the magnitude of this association. The 0.29-point increase in PHQ-9 scores sounds concerning until you understand how this scale actually works. The PHQ-9 runs from 0 to 27, and over such a range, a 0.29-point increase is so subtle as to be clinically insignificant despite its apparent statistical significance. This test was developed for the purpose of assessing where one falls across large bucket ranges (e.g., 0–4: no depression; 5–9: mild depression; etc.) — not for the minute differences observed in this study. (For comparison, when used to assess response to antidepressive treatments, a change of 50% in PHQ-9 score is regarded as a cutoff for “significant” improvement.5)
Attempted diet vs. successful diet?
Just for argument’s sake, let’s pretend that this study could indeed evaluate causal relationships between variables and that the “effect” was clinically meaningful. We still wouldn’t be able to make conclusions about whether calorie restriction truly leads to worsening depressive symptoms thanks to another shortcoming that is common throughout nutritional research: reliance on self-report data. We have no objective evidence that participants actually adhered to their reported dietary strategies. Anyone who’s ever tried to stick to a diet knows there’s often a substantial difference between what we plan to do and what we actually do. Did the people who reported “calorie restriction” actually consume fewer calories? Did they lose weight? Did they sustain their efforts for weeks, months, or just a few days? We simply don’t know. Thus, this study wasn’t designed to test the association between CR and mental health, but rather, the question actually being answered was this: “do people who believe they are restricting calories tend to have worse mental health?”
The psychological impact of attempting restriction might be quite different from the impact of successfully implementing it. Someone who repeatedly tries and fails to stick to a calorie-restricted diet might experience frustration, guilt, and feelings of failure — all of which could worsen depressive symptoms. Meanwhile, someone who successfully maintains a sustainable caloric deficit and sees positive changes in their body composition might experience the opposite – net benefit for mental health. Without objective data on weight changes or calorie intake, we can only speculate about this alternate interpretation of the results, but it certainly demonstrates how self-reported data might be misleading in this context.
The bottom line
With many limitations and such a small effect size, basing any conclusion on these data — as the popular press has done — just adds to the noise already surrounding discussions on nutrition. This study doesn’t provide any reliable evidence that dieting causes depression, let alone enough to motivate a serious reconsideration of earlier research. This single observational study shouldn’t override the substantial body of evidence from controlled trials showing that calorie restriction typically improves mental health outcomes — not to mention the many benefits for metabolic health and prevention of chronic diseases.
Of course, these benefits only materialize when dieting is “successful” — meaning that it facilitates achievement and maintenance of a healthy body weight and body composition. It’s certainly plausible that repeated, unsuccessful attempts at dieting may erode self-esteem and mental health, so perhaps the real takeaway is that how you diet may matter at least as much as whether you diet. Whether adopting an “established diet,” calorie restriction, time restriction, or dietary restriction, focus on approaches that are sustainable yet still help you to achieve your health goals — this is the surest way to maximize both mental and physical well-being through nutrition.
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References
- Menniti G, Meshkat S, Lin Q, Lou W, Reichelt A, Bhat V. Mental health consequences of dietary restriction: increased depressive symptoms in biological men and populations with elevated BMI. BMJ Nutr Prev Health. 2025;8(1):10-20. doi:10.1136/bmjnph-2025-001167
- Ein N, Armstrong B, Vickers K. The effect of a very low calorie diet on subjective depressive symptoms and anxiety: meta-analysis and systematic review. Int J Obes (Lond). 2019;43(7):1444-1455. doi:10.1038/s41366-018-0245-4
- Wigle R. It’s official: Your diet is making you depressed, according to science. New York post. https://nypost.com/2025/06/05/health/science-confirms-your-diet-could-be-making-you-depressed/. June 5, 2025. Accessed July 30, 2025.
- Newton S. Cutting calories can make you depressed – and men and overweight people are particularly vulnerable. Independent. https://www.independent.co.uk/news/health/low-calorie-diet-depression-study-b2762878.html. June 4, 2025. Accessed July 30, 2025.
- Kroenke K, Spitzer RL, Williams JB. The PHQ-9: validity of a brief depression severity measure. J Gen Intern Med. 2001;16(9):606-613. doi:10.1046/j.1525-1497.2001.016009606.x
