What Is Nutritional Psychology? How a Mental Health Dietitian Can Help

Oct 9

5 min read

Have you ever noticed that your mood shifts after a skipped lunch, or that a stressful week sends you straight to the snack cupboard? Many of my clients tell me they know what to eat, yet still feel stuck in cycles of low energy, cravings, emotional eating or guilt around food.

That's because food and mental health are connected in both directions: what you eat affects how you feel, and how you feel affects how you eat. This connection is the heart of nutritional psychology. In this post, I'll explain what nutritional psychology is, what the research shows, and how working with a mental health dietitian can help you boost mood with food.

What is nutritional psychology?

Nutritional psychology is the study of how diet and eating behaviour interact with our mental and emotional health. It looks at the relationship from two angles:

How food affects the brain: the nutrients, eating patterns and gut health that influence mood, focus, energy and stress.
How the mind affects eating: the emotions, thoughts, beliefs and habits that shape what, when and why we eat.

You may also hear the term nutritional psychiatry, a closely related research field focused on how diet can help prevent and manage mental health conditions like depression and anxiety (1). Nutritional psychology takes a slightly wider view: it includes the brain chemistry and the very human side of eating, like stress eating, food guilt and all-or-nothing thinking.

How does food affect mood and mental health?

Research over the past decade has made one thing clear: what's on your plate matters for your brain. Here are a few of the key ways food influences mental health.

1) The gut-brain connection

Your gut and brain are in constant communication through the vagus nerve, hormones, the immune system and the trillions of microbes living in your gut (5). These microbes help produce compounds that influence mood and stress. I dive deeper into this in The Power of Your Gut.

2) Building blocks for neurotransmitters

The brain relies on nutrients from food to make neurotransmitters like serotonin and dopamine. Protein, for example, provides the amino acids tryptophan and tyrosine. Learn more in my post on protein's role in mental health.

3) Blood sugar and energy

Long gaps between meals can lead to dips in blood sugar, which often show up as irritability, brain fog, fatigue and intense cravings later in the day.

4) Inflammation & Oxidation

Diets rich in vegetables, fruit, whole grains, legumes, nuts, fish and olive oil are linked with lower inflammation and oxidation, which is one of the proposed pathways connecting diet and depression (6).

5) Brain structure and function

The brain is one of the most fat-rich organs, and fats form the membranes of every brain cell.

What does the research show?

In the landmark SMILES trial, adults with moderate to severe depression who received dietary support to follow a Mediterranean-style diet saw significantly greater improvements in their symptoms than those who received social support alone (2). A meta-analysis of randomized controlled trials also found that improving diet quality reduced symptoms of depression (3), and large observational studies link healthier eating patterns with a lower risk of depression (4). Curious what this looks like in practice? Check out my 7-day meal plan based on the SMILES trial.

Why your relationship with food matters too

Knowing which foods support mental health is only half the picture. If eating is driven by stress, guilt, restriction or all-or-nothing thinking, it becomes very hard to nourish yourself consistently, even when you know what's "healthy."

For example, strict dieting often sets up a cycle of restriction followed by overeating or bingeing, then guilt and more restriction (7). The good news? Approaches like mindful eating can help reduce binge and emotional eating by building awareness of hunger, fullness and emotions (8).

People with ADHD face their own challenges, too. Forgetting to eat, low appetite on medication and impulsive eating are common, and research shows a link between ADHD and overeating behaviours (9). If this sounds familiar, my post on ADHD medication appetite suppression is a great place to start.

What does a mental health dietitian do?

A mental health dietitian is a Registered Dietitian (RD) who specializes in the connection between nutrition, mood and eating behaviour. As an Ontario based Registered Dietitian specializing in mental health nutrition, I bridge the gap between the science of food and the psychology of eating. My approach focuses on four pillars:

What you eat (balanced nutrition): building simple, balanced meals that nourish your brain and body.
When you eat (meal timing): creating consistent eating patterns that support blood sugar, energy, focus and appetite regulation.
How you eat (mindful eating): tuning in to hunger, fullness and emotions to reduce emotional eating and support digestion.
Why you eat (food mindset): exploring the thoughts, beliefs and feelings behind your eating to overcome binge eating, food guilt and all-or-nothing thinking.

Please note that a dietitian doesn't replace a therapist, psychologist or psychiatrist. Instead, I work alongside your mental health care team to support your wellbeing through nutrition.

Who can benefit from working with a mental health dietitian?

You may benefit from mental health nutrition counselling if you:

Live with anxiety, depression or another mental health condition and want to support your mood through food
Eat when you're stressed, bored or overwhelmed, rather than physically hungry
Experience binge eating or feel out of control around food
Live with ADHD and struggle with forgetting to eat, meal planning or evening overeating
Feel guilt or anxiety around food and want a healthier relationship with eating
Want to manage your weight in a sustainable way, without restrictive diets

Ready to start boosting your mood with food?

→ Book a free 15-minute discovery call

Key takeaways

Nutritional psychology explores how food affects your mental health, and how your mental health affects your eating.
Diet matters for mood. Research, including the SMILES trial, shows that improving diet quality can reduce symptoms of depression.
Your gut and brain are connected, and nourishing your gut supports your mind.
Your relationship with food matters just as much as what's on your plate.
A mental health dietitian helps with what, when, how and why you eat, alongside your mental health care team.

References

Adan RAH, van der Beek EM, Buitelaar JK, et al. Nutritional psychiatry: towards improving mental health by what you eat. Eur Neuropsychopharmacol. 2019;29(12):1321-32.
Jacka FN, O'Neil A, Opie R, et al. A randomised controlled trial of dietary improvement for adults with major depression (the 'SMILES' trial). BMC Med. 2017;15(1):23.
Firth J, Marx W, Dash S, et al. The effects of dietary improvement on symptoms of depression and anxiety: a meta-analysis of randomized controlled trials. Psychosom Med. 2019;81(3):265-80.
Lassale C, Batty GD, Baghdadli A, et al. Healthy dietary indices and risk of depressive outcomes: a systematic review and meta-analysis of observational studies. Mol Psychiatry. 2019;24(7):965-86.
Cryan JF, O'Riordan KJ, Cowan CSM, et al. The microbiota-gut-brain axis. Physiol Rev. 2019;99(4):1877-2013.
Marx W, Lane M, Hockey M, et al. Diet and depression: exploring the biological mechanisms of action. Mol Psychiatry. 2021;26(1):134-50.
Polivy J, Herman CP. Dieting and binging: a causal analysis. Am Psychol. 1985;40(2):193-201.
Katterman SN, Kleinman BM, Hood MM, et al. Mindfulness meditation as an intervention for binge eating, emotional eating, and weight loss: a systematic review. Eat Behav. 2014;15(2):197-204.
Kaisari P, Dourish CT, Higgs S. Attention deficit hyperactivity disorder (ADHD) and disordered eating behaviour: a systematic review and a framework for future research. Clin Psychol Rev. 2017;53:109-21.