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A client shares their excitement about a low-carb diet, describing an initial boost in energy and mental clarity. But a few weeks later, they’re back, frustrated by mood swings, fatigue, and cravings they didn’t expect. These stories are all too common, and they highlight just how complicated the relationship between low-carb diets and mental health can be.
Low-carb diets are often praised for quick results, but the research reveals a more nuanced picture.
For some, cutting carbs may lead to short-term benefits, like stabilized energy or fewer sugar cravings. But others face challenges, including irritability, trouble sleeping, dysregulated blood sugar, and difficulty concentrating.
When we step back and look at the bigger picture, it’s clear that extreme carbohydrate restriction doesn’t happen in isolation. It influences mood, energy, and mental health in ways shaped by factors like fiber intake, cultural dietary practices, and the psychological strain of restrictive eating.
What Do We Mean by Low-Carb?
If the term “low-carb” leaves you scratching your head, you’re not alone. One of the biggest challenges in research and practice is the lack of a universal definition.
In some studies, “low-carb” means fewer than 15 grams of carbohydrates per day—a level so restrictive it excludes most fruits, grains, and even some non-starchy vegetables. Other studies take a much broader view, defining low-carb as anything under 200 grams per day, which can still include pasta, bread, and an array of plant-based foods.
*note, the SAD is estimated to be at least 250 g carbs per day.
This isn’t just a matter of semantics; these discrepancies have real implications. They make it harder to interpret research findings and provide clear, evidence-based guidance to clients.
Why Definitions Matter
The degree of carbohydrate restriction in a diet has a profound impact on both physiology and psychology. At very low levels—under 50 grams per day—the body enters ketosis, shifting energy metabolism and influencing mood-regulating neurotransmitters like serotonin.
In contrast, a moderately low-carb approach (150–300 grams per day) can stabilize blood sugar and reduce sugar cravings without triggering the dramatic physiological changes associated with ketosis.
These distinctions are crucial when evaluating outcomes. A client on a strict ketogenic diet might experience brain fog, mood swings, or erratic energy levels, particularly during the adjustment period. Meanwhile, someone following a more moderate low-carb plan may feel steady, energized, and satisfied.
Without a clear and consistent definition of “low-carb,” it becomes challenging to set realistic expectations or critically evaluate the evidence for these diets.
Potential benefits of low-carb diets on mental and physical health
Low-carb diets may offer some benefits for mental and physical health, particularly in certain populations. For example, they can help reduce the risk of metabolic syndrome and type 2 diabetes—conditions that often co-occur with psychiatric disorders. (It’s worth noting, however, that moderate-carb diets can achieve similar results.)
Some research suggests that ketogenic diets may lower inflammation compared to the Standard American Diet (SAD). However, direct comparisons between ketogenic diets and other health-promoting dietary patterns—such as the Mediterranean Diet, Traditional Japanese Diet, or DASH—are limited. These diets are also known to reduce systemic inflammation and may offer comparable or even superior outcomes.
For some clients, the structure of a low-carb diet provides a sense of control or stability, particularly if they feel a lack of control in other areas of their lives. While this can be beneficial for some, it may also increase the risk of disordered eating behaviors. This underscores the importance of dietitian oversight when clients are following carb-restricted plans to ensure both physical and psychological health are supported.
Potential drawbacks of low-carb diets on mental and physical health
While low-carb diets may offer certain benefits, they also have notable drawbacks, particularly when followed long-term or without professional guidance.
One significant challenge is adherence. Many favorite foods—especially those commonly enjoyed at social gatherings—are no longer permitted. Social interaction is a critical factor in positive mental health outcomes, and individuals on low-carb diets, particularly ketogenic diets, often begin avoiding social events as a result.
Drastically reducing carbohydrate intake can also increase the risk of nutrient deficiencies, as it limits access to certain vitamins and minerals found in carb-rich foods.
There is moderate evidence that diets with fewer than ~130 grams of carbohydrates per day can negatively impact sleep and mood. This is partly due to interference with the production of serotonin and melatonin, which are essential for regulating both.
Feelings of deprivation can also trigger a restrict-binge cycle, harming both mental and physical health. For individuals with eating disorders or a history of disordered eating, these risks are even greater. Carb-restricted diets are particularly inappropriate for this population and should be approached with caution.
Specific Concerns with Ketogenic Diets
Ketogenic diets carry additional risks.
In the early stages, many individuals experience “keto flu,” which can cause symptoms like malaise, headache, nausea, fatigue, weakness, gastrointestinal issues, and changes in heart rate. Gastrointestinal symptoms may persist and require medical intervention or supplementation.
Without careful monitoring, ketogenic diets can lead to dehydration, electrolyte imbalances, hypercholesterolemia, and deficiencies in micronutrients like B vitamins, vitamins A and E, calcium, magnesium, and potassium.
Long-term effects may include:
- Hyperlipidemia and hypertriglyceridemia
- Kidney stones
- Increased risk of heart and liver disease
- Reduced bone density
- Menstrual cycle irregularities and fetal complications
- Worsening nutrient deficiencies
Additionally, for individuals taking antipsychotic medications, ketogenic diets may exacerbate blood lipid abnormalities, compounding health risks.
Mental Health Impacts—The Full Spectrum
Mood and Energy
Negative Evidence:
A systemic review in 2016 found no significant benefits of low-carb or ketogenic diets on psychosocial outcomes compared to other macronutrient-focused interventions in short and “intermediate-long-term” research.
Research in children with intractable epilepsy provides additional insight, though on a smaller scale. A 2012 study of just 11 participants showed that while the ketogenic diet did not negatively affect cognition or social interactions, it did appear to increase mood-related problems.
A meta-analysis in 2022 showed no association between a low-carb diet and anxiety and depression. However, when 1 particular study was excluded, the evidence pointed to an increase in anxiety symptoms. The usual limitations applied (no standardized definition of low carb, difficulty in blinding participants, etc.).
More recent findings highlight the complexity of this topic. A 2022 meta-analysis examined the relationship between low-carb diets and symptoms of anxiety and depression. The initial analysis found no clear association, but when one specific study was excluded, the remaining evidence pointed to an increase in anxiety symptoms.
This underscores common challenges in this area of research: the lack of a standardized definition for “low-carb” and the difficulty of blinding participants often limit the strength of conclusions.
A study comparing low-fat (LF) and low-carb (LC) diets adds another layer to the discussion. While participants on the LF diet showed improved mood and overall psychological well-being, those on the LC diet did not experience the same benefits.
Both groups, however, demonstrated similar enhancements in working memory and processing speed. One major caveat is that the LC intervention used in this study was a very low-carb diet, which likely influenced the results.
Reflecting on this body of evidence, it seems likely that a moderately carb-restricted diet might bridge the gap between the benefits observed in low-fat diets and the drawbacks of extreme carb restriction. Unfortunately, this middle ground remains underexplored, leaving us with important unanswered questions about the nuanced effects of carbohydrate intake on mood and energy.
Supportive Evidence
The concept of “energy” is deeply subjective, making it challenging to measure or study consistently. Most positive reports I encountered came from anecdotal sources, such as online forums. Some individuals describe feeling more energetic and experiencing reduced anxiety after adopting a low-carb diet.
However, others share a very different experience, reporting extreme fatigue that interferes with waking up on time, fulfilling work responsibilities, and maintaining social connections. This stark contrast highlights how dietary changes can dramatically impact people differently.
From a physiological perspective, it’s likely that those who feel better on a low-carb diet are benefiting from more stable glucose levels throughout the day. Significant fluctuations in blood glucose can lead to feelings of anxiety, while low blood sugar often causes fatigue.
Maintaining steadier glucose levels could explain improvements in energy and mood for some individuals. That said, I can’t find a study that directly examines this connection.
For clients experimenting with dietary changes, encouraging them to track their mood, energy levels, and concentration throughout the day can provide valuable insights. These patterns not only help guide dietary adjustments but also reinforce a personalized approach to supporting mental and physical health.
Cognition and Clarity
Negative Evidence:
Research on the cognitive impacts of low-carb diets is limited, but what we do have raises some concerns.
A small 2009 study involving just 19 participants over three weeks found that individuals on a low-carb diet performed worse on memory-related cognitive tasks compared to those following the “ADA diet.” These impairments resolved when carbohydrate-containing foods were reintroduced.
This finding aligns with anecdotal accounts from my clients, many of whom describe feeling mentally sluggish or struggling with focus during past low-carb dieting attempts.
The low-carb group did experience more “vigilance,” though it is unclear what benefit this provided them. In the discussion, the authors present studies that show a high-carb diet improves performance on “high-load cognitive tasks” and cite older studies that demonstrated better short-term memory when glucose and other carbohydrates were given to participants.
These findings suggest that while some individuals may perceive heightened alertness on a low-carb diet, others might experience cognitive challenges, particularly in areas like memory and complex problem-solving. As always, individual responses vary, but these nuances are essential for dietitians and therapists to consider when tailoring interventions.
Supportive Evidence:
A randomized controlled trial conducted in 2016 explored the effects of a ketogenic diet (KD) on behavior and cognitive functioning in a very specific population: children and adolescents with intractable epilepsy.
The findings were intriguing. Participants on the ketogenic diet showed improvements in mood and cognitive abilities, and these changes were observed independently of improvements in seizure activity. This answered one of my biggest questions when I first encountered the study: Were these benefits simply a side effect of better seizure control, or was something more directly at play?
Interestingly, the ketogenic group performed significantly better in vocabulary testing than the treatment-as-usual (TAU) group. However, this advantage came with a trade-off: slower mental reaction times.
With only 50 participants in the study, it’s possible that unrecognized factors or patterns influenced these results. Still, the findings shed light on the complex interplay between diet, cognition, and mental health, particularly in this unique clinical context.
Schizophrenia (SZ)
Supportive Evidence
Emerging evidence suggests that schizophrenia may be linked to damaged glycolytic processes in the brain, impairing its ability to utilize glucose effectively. The theory behind the ketogenic diet as a potential intervention is fascinating—it aims to bypass these damaged pathways by providing an alternative fuel source in the form of ketones, potentially normalizing brain metabolism.
A study exploring this theory presented two compelling case studies. Both participants showed improvements in the negative and cognitive symptoms of schizophrenia—symptoms that had previously been unresponsive to medication. While the results are intriguing, they come with significant limitations.
It’s actually kind of a cool theory, and the study linked above presented 2 case studies that demonstrated the positive effects of a ketogenic diet on both the negative and the cognitive symptoms of schizophrenia—symptoms that had previously been unresponsive to medication.
While the results are intriguing, they come with significant limitations.
A review of research on ketogenic diets for schizophrenia through 2024 highlights the generally poor quality of the studies. Many failed to adequately monitor participants’ diets or confirm ketosis, a critical factor in assessing the diet’s efficacy.
None of the studies included a control arm, and the largest study consisted of only 10 participants. Study durations varied widely, ranging from as little as two weeks to four months.
The case studies followed the participants for up to 12 years (1 year, 5 years, 12 years).
Negative Evidence
I am unable to find any literature that directly shows a low-carb or ketogenic diet worsening the symptoms or management of schizophrenia. While this might seem encouraging at first glance, the absence of negative findings doesn’t necessarily equate to strong support for the diet as a treatment option.
Remember that publication bias causes studies with positive results to be more likely to be submitted and then approved for publication than studies with negative results.
My take? The theory behind ketogenic diets and schizophrenia is undeniably intriguing and worth further exploration.
However, the current state of the research lacks the rigor needed to recommend such a diet as a viable intervention. This is particularly relevant when considering the real-world challenges faced by individuals with schizophrenia. Food insecurity is a significant concern for this population, and the restrictive nature and potential cost of a ketogenic diet could exacerbate these challenges.
Bipolar Disorder (BD)
Supportive Evidence
Support for ketogenic diets in managing bipolar disorder stems from theories around oxidative stress and mitochondrial dysfunction as potential underlying mechanisms. The idea is that switching the brain’s primary fuel source from glucose to ketones may bypass these mitochondrial impairments, effectively normalizing energy metabolism.
Another interesting angle involves lactate levels. Individuals with bipolar disorder often exhibit lower lactate levels compared to the general population, and ketogenic diets have been shown to elevate lactate levels, potentially addressing this imbalance.
While the research here is a bit more robust than what’s been conducted for schizophrenia, it still leaves much to be desired. Two studies with small sample sizes (n=16 and n=27) have shown promising results, but they lacked control arms and were limited to short durations of 2–8 weeks.
That said, these studies had stronger methodologies than many others in this area. Participants were better monitored for ketosis through blood or urine tests, and outcomes were quantified using global indices. These metrics revealed reductions in key symptoms like psychosis, depression, anxiety, and improvements in overall quality of life.
Though the evidence is preliminary, it points toward a need for larger, more rigorous studies to fully understand the role of ketogenic diets in managing bipolar disorder.
Negative Evidence
While there’s interest in how ketogenic diets might support individuals with bipolar disorder, there are significant concerns about their potential drawbacks—particularly for those on medication.
One documented case reported the onset of mania and psychosis after starting a ketogenic diet, believed to stem from altered metabolism of the mood stabilizer Depakote (valproic acid).
This highlights a critical interaction: ketosis can interfere with the medications Depakote, Zonegran (zonisamide), and Topamax (topiramate), leading to either increased side effects or reduced effectiveness. Lithium levels may also be impacted by dietary changes, complicating treatment further.
Beyond the clinical evidence, anecdotal accounts from forums are filled with individuals who experienced worsened psychiatric symptoms, forcing them to abandon low-carb diets altogether.
My take? While there are fascinating theories about the potential benefits of ketogenic diets for bipolar disorder, the evidence remains too preliminary to recommend such an approach broadly. The risks, especially when medications are involved, cannot be ignored. For now, any consideration of a low-carb diet should be approached with caution and under close medical supervision.
Major Depressive Disorder (MDD)
Supportive Evidence
Research has consistently linked MDD with increased markers of inflammation.
The proposed mechanism for ketogenic diets in this context is that they may reduce low-grade inflammation and positively influence gut microbiota. However, the explanation remains vague, with authors often citing generalized claims about gut health without concrete evidence.
Some small, short-term studies without control arms suggest that ketogenic diets can improve certain depressive symptoms. While promising, the lack of rigorous study design limits the reliability of these findings.
Negative Evidence
Nutrient deficiencies known to exacerbate depression—such as folate, niacin, and magnesium—are often more prevalent in low-carb diets. These deficiencies may undermine any potential benefits of carbohydrate restriction, particularly for individuals already struggling with mood stability.
Equally concerning is the reduced intake of dietary fiber on low-carb and ketogenic diets.
Fiber is vital in maintaining a healthy gut microbiome, significantly impacting mood regulation and stability. Severe fiber limitations on ketogenic diets and moderate reductions on other low-carb approaches may negatively affect mental health outcomes, counteracting any benefits from inflammation reduction.
My take? While there’s some intriguing early evidence that ketogenic diets might help with MDD symptoms, the risks—particularly related to nutrient deficiencies and fiber intake—are considerable.
These diets are far from a one-size-fits-all solution and require careful planning to avoid inadvertently worsening depressive symptoms. For most individuals, a more balanced diet that supports gut health and meets nutrient needs may be a more sustainable and effective approach.
Substance Use Disorder
The Connection Between Sugar Cravings and Withdrawal
After detox, individuals recovering from substance use often face overwhelming sugar cravings. This is likely due to alterations in glucose metabolism caused by the substance itself, and is particularly pronounced in alcohol and opioid cessation.
Some research suggests that ketogenic diets may help address these cravings and alleviate withdrawal symptoms by bypassing the damaged metabolic pathways. This approach offers a fascinating and promising avenue for improving recovery outcomes, especially in cases of Alcohol Use Disorder.
Balancing Potential Benefits with Risks
The article linked above delves into this topic thoroughly, outlining the metabolic changes in recovery and how a ketogenic diet could offer relief.
However, the authors caution that the adverse effects of a ketogenic diet—when combined with the comorbidities common in substance use recovery—could outweigh potential benefits. Issues such as nutrient deficiencies, electrolyte imbalances, and the diet’s restrictive nature are particularly concerning.
Of all the literature I’ve combed through for this article, this one strikes me as the most interesting.
Practical Limitations in Recovery Settings
The practicalities of implementing a ketogenic diet in recovery settings add another layer of complexity. Many individuals in recovery struggle with poor appetite, gastrointestinal issues, and the multi-system disorders caused by long-term substance use.
These challenges are compounded in residential treatment programs, where logistical barriers like food costs, managing dietary restrictions, and meeting state regulations make adherence to a ketogenic diet even less feasible.
My take?
While the theory and initial findings are compelling, the practical challenges of implementing a ketogenic diet during recovery are significant.
Additionally, the potential for adverse effects makes this an intervention that should be approached cautiously and only under close supervision. A more accessible approach might focus on supporting stable blood sugar and balanced nutrition with fewer risks and logistical hurdles.
Neurodivergence
Many members of the community have challenged the idea that neurodivergence needs to be “fixed.”
These conditions exist on a broad spectrum, and therapies typically focus on managing co-occurring challenges like sensory processing disorders, social anxiety, and occupational skills.
While most neurodivergent conditions are genetic and related to brain structure—factors that aren’t modifiable through diet—there is still a role for nutrition in addressing associated health issues.
Co-Occurring Health Conditions and Nutrition’s Role
Individuals with neurodivergent conditions, such as Autism Spectrum Disorder (ASD) and Attention-Deficit/Hyperactivity Disorder (ADHD), experience higher rates of gastrointestinal disorders, including IBS, IBD, and Celiac disease. Additionally, substance use disorders and eating disorders, including ARFID, are more prevalent in these populations.
Nutrition interventions can significantly improve overall health and quality of life by managing these co-occurring conditions. While nutrition needs don’t differ specifically because of neurodivergence, addressing these overlapping health challenges can provide meaningful support.
My take?
Dietary changes won’t alter the neurological structure underpinning neurodivergence, but nutrition can be a powerful tool for managing associated physical and mental health challenges. Focusing on accessible, individualized strategies that address coexisting conditions is a practical and inclusive approach.
For many neurodivergent individuals, sensory disorders can significantly limit food choices, as textures, smells, or even the appearance of certain foods may feel overwhelming or intolerable. This sensory sensitivity can lead to a restricted diet, which increases the risk of nutrient deficiencies over time.
Upcoming Research
Upcoming research shows promise in addressing the limitations of past studies on low-carb and ketogenic diets.
While the sample sizes remain relatively small, they are larger than those in previous studies, and many include a control arm—an essential step forward. Control groups vary, with some participants continuing with ad libitum eating or diet-as-usual approaches.
Notably, one study will compare a ketogenic diet to standard hospital meals, while two others will evaluate outcomes against diets aligned with general dietary guidelines for health. These designs offer a more balanced perspective and could help clarify the role of low-carb diets in various health conditions.
Potential Risks of Low-Carb Diets
Restrictive Eating Patterns:
Restrictive eating patterns are a common concern with low-carb diets, often leading to cycles of over-restriction and subsequent binge eating. This dynamic occurs because individuals can only sustain an overly controlled approach for so long before it results in a loss of control, often in the form of overindulging in restricted foods. Food and nutrition are no exceptions to this pattern.
Many of my clients feel a palpable sense of relief when I assure them they can include their favorite foods.
Together, we shift the focus toward positive and sustainable goals, like adding more vegetables, staying hydrated, or incorporating nuts and seeds into meals. As they work on mindful eating and explore mindfulness beyond individual meals, they naturally gravitate toward balanced eating patterns—reducing sugary and fried foods without experiencing guilt, shame, or a sense of “cheating.”
Social and Emotional Risks:
Low-carb diets, particularly those that are highly restrictive, can have significant social and emotional repercussions. Food is often central to social interactions, from celebratory cakes to game nights with snacks, weekend wine nights, or popcorn at the movies. When certain foods or drinks are off-limits, it can make these moments feel isolating rather than joyful.
Moderately low-carb diets can often be managed flexibly, allowing individuals to participate in these events more comfortably. However, strict ketogenic diets frequently come with a rigid “no cheating” mindset.
This can force individuals to skip social gatherings or attend and watch others enjoy foods they can’t have, leading to feelings of exclusion or resentment. Over time, this isolation can negatively impact mental health and overall well-being, highlighting the importance of balance and flexibility in dietary choices.
Any diet or lifestyle intervention that interferes with an individual’s (positive) social interactions harms that individual, with no exceptions.
Note: This type of social isolation is not limited to low-carb diets. Any “diet,” particularly those that are commonly used for weight loss, can have the same effect.
Nutritional Deficiencies:
A ketogenic diet poses a significant risk of nutritional deficiencies, including folic acid, thiamine, calcium, magnesium, potassium, and vitamins A, B6, and E. In some cases, protein and fiber deficiencies are also observed.
These deficiencies not only lead to the classic symptoms and conditions we learned in nutrition school but are also directly implicated in affective disorders, further underscoring the connection between diet and mental health.
Keto proponents often argue that the diet is nutritionally complete and place blame on individuals for “not doing it right” when deficiencies arise. However, this is a hallmark of nutrition red flags.
In reality, ketogenic diets are highly restrictive and require careful planning, ideally under the supervision of medical and nutrition professionals, to ensure nutritional adequacy and avoid harm.
Metabolic and Other Health Risks
Research suggests that low-carb diets do not offer a significant advantage over more traditional, balanced, energy-restricted diets for weight loss or maintenance. Although short-term results can be appealing, especially in the initial phases of the diet, the potential for long-term health complications is a serious concern.
Extended carbohydrate restriction has been linked to a variety of metabolic and physical health issues. These include impaired cardiac function, heart arrhythmias, and even sudden death.
Additionally, long-term adherence to low-carb diets can contribute to osteoporosis, kidney damage, and an increased risk of certain cancers. Nutrient imbalances due to reduced carb intake may also interfere with physical performance, making it harder to sustain an active lifestyle.
While the growing interest in ketogenic diets could pave the way for more nuanced research, it highlights the current lack of consensus on their safety and efficacy, especially in the context of serious mental illness. A large-scale study comparing ketogenic diets to the Standard American Diet, the Mediterranean Diet, and moderately restricted carbohydrate diets would provide much-needed clarity on their impact on mental and physical health.
The Role of Fiber and Carbohydrate Quality
When examining the effects of low-carb and ketogenic diets, one important factor that often gets overlooked is the quality of carbohydrates being consumed. Many studies comparing moderate- to high-carb diets to low-carb or ketogenic diets fail to distinguish between different types of carbohydrates.
For instance, there’s a significant difference between the carbohydrate sources in a Mediterranean Diet, which includes whole grains, fruits, and starchy vegetables, and the Standard American Diet, which is high in refined sugars and processed foods. Yet, both are often grouped together as a “standard” diet or “treatment as usual,” failing to address the nuances in diet quality.
The same goes for other traditional/heritage diets.
Whole grains, fruits, and starchy vegetables all positively affect systemic inflammation and the gut microbiome, the very thing proponents claim for the ketogenic diets.
Therefore, it’s not just the amount of carbohydrates but the quality of those carbohydrates that matters in reducing inflammation and supporting overall health.
Fiber, which is abundant in high-quality carbohydrate sources, has profound mental health benefits. A 2021 cross-sectional study of over 3,300 adults found that greater fiber intake was inversely related to anxiety and psychological distress. This relationship supports the idea that fiber can play a role in stabilizing mood and reducing anxiety.
Furthermore, a 2023 study using NHANES data on over 8,000 adults showed that adequate fiber intake can mitigate the negative effects of elevated C-reactive protein (a marker of inflammation) on mood and anxiety levels.
Ultimately, the quality of carbohydrates and the inclusion of fiber-rich foods may offer significant mental and physical health benefits that are not captured when comparing low-carb diets to other eating patterns without considering the types of carbohydrates frequently consumed.
The ability of individuals to maintain a balanced diet without resorting to restrictive eating patterns or the restrict-binge cycle will determine their long-term success in managing both physical health and mental well-being.
Additional studies that show the positive effect of high fiber intake on mental health:
- Association of dietary fiber and depression symptom: A systematic review and meta-analysis of observational studies
- “An increased intake of total dietary fiber is associated with lower odds of depression.”
- Dietary fiber intake, depression, and anxiety: a systematic review and meta-analysis of epidemiologic studies
- “High intake of dietary fiber was protectively associated with depression in adults, in a dose-response fashion.”
- Fiber intake and fiber intervention in depression and anxiety: a systematic review and meta-analysis of observational studies and randomized controlled trials
- “Although observational data suggest a potential benefit for higher fiber intake for depressive and anxiety outcomes, evidence from current RCTs does not support fiber supplementation for improving depressive or anxiety outcomes. More research, including RCTs in clinical populations and using a broad range of fibers, is needed.”
- This is consistent with research that indicates that the variety of fiber intake is just as important as the amount.
- Effect of dietary fibre on cognitive function and mental health in children and adolescents: a systematic review and meta-analysis
- “Evidence from observation studies demonstrated that higher dietary fibre consumption is associated with a decreased odds of depression symptoms, both in childhood and adolescence.”
- Effects of Dietary Fiber, Phenolic Compounds, and Fatty Acids on Mental Health: Possible Interactions with Genetic and Epigenetic Aspects
- “Prebiotic fiber, through its effects on GM (gut microbiota), has been associated with a modulation in the neuroendocrine response to stress and the facilitation of the processing of positive emotions.”
- There’s more, but you get the idea.
To me, the key takeaway from the research is that moderation, not elimination or extreme restriction, is the most beneficial approach to carbohydrate intake for supporting mental and physical health. Rather than adhering to rigid, low-carb diets, individuals can experience positive effects on their mood and overall well-being by focusing on balance and quality in their carbohydrate choices.
This approach allows clients and patients to continue enjoying their favorite foods without the guilt or stress that often accompanies restrictive eating patterns. It promotes more sustainable eating habits and reduces the harmful restrict-binge cycle.
As a result, both physical and mental health improve, and individuals can maintain meaningful social interactions without feeling isolated or deprived.
In short, moderate carbohydrate intake that prioritizes high-quality sources—like whole grains, fruits, and vegetables—can foster a healthier, more balanced relationship with food while supporting emotional well-being.
Clinical Considerations and Practical Applications
When Low-Carb May Be Appropriate:
The decision to recommend (or follow) a low-carb diet really depends on how you define “low-carb.”
If you’re talking about reducing carbohydrate intake compared to the Standard American Diet (SAD), then this can be a helpful and appropriate choice for many individuals. Reducing carbohydrate intake can improve health markers without requiring extreme restrictions.
However, when carbohydrate intake falls below 130 grams daily, the risks of adverse effects—like nutrient deficiencies, hormonal imbalances, and impacts on mental health—become more pronounced. This level of restriction is generally unnecessary for most people and should be approached with caution.
One notable exception is for children with intractable epilepsy. In these cases, the ketogenic diet has a well-established track record of being effective in reducing seizures, and the research in this area is compelling. For these individuals, the benefits often outweigh the risks, but ongoing medical supervision is crucial.
Guiding Clients Through the Evidence:
Navigating nutrition research can be challenging for healthcare providers but is even more overwhelming for clients without a clinical background.
Often, clients are exposed to contradictory information from sources like social media influencers who present themselves as “experts” in wellness. Their claims may sound plausible and authoritative, but they rarely consider the full range of scientific research or the nuances of individual health needs.
In these situations, it’s important to offer clear, evidence-based guidance that helps clients understand the complexities of nutrition. While “It depends” may be the dietitian’s go-to response, it’s important to empower clients by breaking down the science in a digestible and non-intimidating way.
I find it helpful to keep a curated set of resources, such as infographics or articles, to explain complex concepts like nutrition red flags—number one being any claim of 100% effectiveness.
Another valuable tool is maintaining a list of resources that objectively explore both sides of a topic. While some websites may have a great take on one issue, they might be biased on another.
When I give a client a resource or link, I keep track of it (when I remember) so that the next time the question comes up, I can just copy and paste rather than re-invent the wheel every time.
This does double duty; I can offer the client a well-written article that can further our conversation and dive into the research on a very specific topic that I likely wouldn’t have looked at otherwise. Also, I don’t have to spend time creating a resource or writing an article every time a question comes up.
Ultimately, guiding clients through the maze of conflicting information is about building trust and offering support in a way that feels accessible, relatable, and, most importantly, grounded in science.
Promoting Balanced Eating
Instead of adopting extreme carb-cutting measures, a more effective and sustainable approach focuses on balance and variety in the diet.
Prioritizing nutrient-dense foods like fiber-rich whole grains, colorful fruits and vegetables, and minimally processed ingredients provides essential nutrients that support both physical and mental health without the risks associated with severe dietary restrictions.
Fiber plays a particularly vital role in this balance. It helps regulate blood sugar levels, which is crucial for mood stability, especially for those dealing with mental health challenges like anxiety or depression. Additionally, fiber nourishes the gut microbiome—a key player in the gut-brain connection.
The microbiome influences everything from cognition to emotional regulation, underscoring the importance of a fiber-rich diet.
Foods like lentils, berries, and oats are especially beneficial. They provide prebiotic fiber that supports the growth of beneficial gut bacteria while offering steady, sustained energy. This combination makes them ideal for promoting mental clarity, mood stability, and overall physical health.
Nuts and seeds are also great, offering fiber, protein, poly- and monounsaturated fats, magnesium, and zinc.
Encouraging clients to focus on what to include in their diet, rather than obsessing over what to avoid, shifts away from an all-or-nothing mindset, also called dichotomous thinking.
This approach helps them move toward a more sustainable relationship with food, supporting mental and emotional well-being. By fostering balanced and mindful eating, clients can enjoy cultural staples and personal favorites, creating a more enjoyable and lasting connection to food.
Tips for maintaining mental well-being while following a low-carb diet
For clients committed to a low-carb approach, supporting mental well-being requires intentional planning. These strategies can help mitigate potential downsides and promote a balanced, sustainable way of eating that supports both physical and mental health.
1. Focus on Nutrient-Dense, Whole Foods
Encourage clients to prioritize nutrient-dense, whole foods over highly processed low-carb products. By incorporating non-starchy vegetables, leafy greens, and low-carb fruits like berries and melons, they can ensure they are getting the vitamins, minerals, and antioxidants necessary for brain health.
These nutrients support energy levels, focus, and mood stability, helping to prevent the cognitive fog and irritability that can sometimes accompany restrictive diets.
2. Stay Hydrated and Monitor Electrolyte Levels
Carbohydrate restriction can lead to increased water and electrolyte losses, particularly in the early stages of a low-carb diet. If hydration and electrolyte balance are not carefully managed, clients may experience fatigue, headaches, and irritability, which can negatively impact their mental well-being.
Advise clients to drink plenty of water and include electrolyte-rich foods like avocados (potassium), nuts and seeds (magnesium), and a pinch of salt in their meals to help maintain sodium levels and prevent these issues.
3. Incorporate Healthy Fats and Protein Sources
A balanced, low-carb diet should include poly- and monounsaturated fats and high-quality protein sources. These macronutrients provide sustained energy and support neurotransmitter production, which is critical for mental clarity and mood regulation.
Fatty fish, eggs, olive oil, nuts, seeds, and avocados are excellent options. These foods are rich in brain-boosting nutrients like omega-3 fatty acids and choline, which promote cognitive function, help manage cravings, and support overall mood stability.
By focusing on these foundational tips, clients can navigate the challenges of a low-carb diet more effectively. These strategies will help them maintain mental well-being, honor their dietary preferences, and continue to work toward their health goals without sacrificing mood or cognitive function.
Call to Research
The intersection of low-carb diets and mental health is an area ripe for further exploration. While existing research highlights both potential benefits and risks, significant gaps remain. We need more studies that:
- Standardize Definitions: Establish clear, consistent thresholds for what constitutes “low-carb” to improve the comparability of research findings.
- Compare Low-Carb Diets to Health-Promoting Dietary Patterns: Shift the focus away from comparisons with the Standard American Diet and toward evaluating low-carb diets against established, evidence-based eating patterns like the Dietary Guidelines, DASH, Mediterranean, traditional Japanese, or Nordic diets.
- Investigate Diverse Populations: To ensure the findings are inclusive and applicable to diverse groups, include individuals from varied cultural, socioeconomic, and dietary backgrounds.
- Examine Long-Term Effects: Focus on the sustainability of low-carb diets and their long-term impact on mental health outcomes, particularly for conditions like bipolar disorder, schizophrenia, and substance use disorders.
- Evaluate Psychological Impacts: Explore how restrictive eating patterns influence mental health, including the potential for disordered eating behaviors or binge-restrict cycles and social isolation.
- Expand Beyond Depression: Move beyond the primary focus on depression to examine other mental health conditions, such as schizophrenia, addiction, and the dysglycemia-anxiety connection.
By addressing these gaps, researchers can provide clearer guidance for practitioners and empower clients to make evidence-informed decisions that align with their needs and mental well-being.
Final Thoughts
Low-carb diets may appeal to clients seeking quick fixes or mental clarity, but the broader picture often tells a different story. Research and experience show that while some may see benefits, many face challenges like mood instability, fatigue, and the mental strain of restrictive eating.
As professionals, it’s important to move beyond rigid dietary rules and help clients find balance. Encouraging high-quality, fiber-rich carbohydrates can support both mental and physical health, offering a sustainable approach that prioritizes well-being over perfection.
By staying curious about the evidence and compassionate in our guidance, we can empower clients to make choices that honor their mental health, cultural traditions, and individual needs.