How Food Choices Affect Both Poop and Mood in Toddlers

Toddlers are known for big feelings and messy diapers. Believe it or not, what they eat can play a big role in both. What you serve them, how much they eat, and even when they eat can all affect their behavior and digestion throughout the day (1).

But this is good news! That means you have more control than you think when it comes to the unpredictable parts of toddlerhood like meltdowns and poop problems.

So let’s break how food connects to both your little one’s mood and their poop, and what small shifts might help.

The Gut-Brain Connection 

One of the main ways food impacts your toddler is through the gut-brain axis. This is the communication highway between the belly and the brain, allowing them to “talk” to each other through hormones and nerves.

For example, around 90% of the body’s serotonin (a neurotransmitter that helps regulate mood and sleep) is produced in the gut (2). This is why toddlers may feel more irritable, anxious, or low-energy when their gut isn’t functioning well. 

These mood-regulating chemicals are directly impacted by what's going on in their digestive system.

How to Tell If Food Is Affecting Your Toddler’s Poop and Mood

It might feel like your toddler is so unregulated that it’s difficult to identify a “baseline” for mood and digestion. In this case, it might be helpful to track their mood changes and poops to establish patterns and what’s “regular” for them. This is also a great tool to bring to your toddler’s pediatrician to help you better communicate your concerns!

Once you’ve established a baseline, here are some signs that food might be impacting your little one’s poop and emotions (3):

• Big mood swings that come and go quickly

• Pooping at random times with no pattern

• Poop that’s often too hard, too loose, or inconsistent

• Tummy pain that seems frequent but has no clear cause

• Low energy or low appetite

• GI symptoms paired with changes in interest in play or learning

Nutrients That Impact Both Poop and Mood

While overall diet matters, some nutrients have a stronger effect on your kid’s digestion and emotions. 

Here’s what to focus on:

Fiber

Fiber is a superfood when it comes to helping both the belly and the brain. It supports regular, soft poops, slows digestion for more stable energy, and even helps avoid those sudden “hangry” meltdowns. 

Some studies also suggest fiber can support better thinking and self-regulation skills in young kids (4).

High-fiber foods to include regularly:

• Beans

• Lentils

• Whole grain carbs

• Avocado

• Raspeberries

• Chia Seeds

• Oats 

• Pears

• Apples

Hydration

Proper hydration can prevent chronic issues with your kiddo’s mood and digestion. Even mild dehydration can lead to sleepiness, irritability, headaches and muscle weakness - which manifest in “out of control” behavior” (5).

This sort of dehydration also contributes to constipation and hard, painful poops (no matter how much fiber they eat).

To keep your kiddo properly hydrated, the American Academy of Pediatrics recommends:

• Ages 1–4: 4 cups water per day

• Ages 4–8: 5 cups water per day

• Ages 8+: 7–8 cups water per day

Protein + Complex Carbs

Pairing a protein with a fiber-rich carb at meals helps keep energy steady and moods more even. These combos slow digestion, keep your kiddo fuller longer, and help avoid the crash that comes after too much sugar or processed snacks.

If your little one is melting down between meals, one of the best first steps is making sure there’s some protein and fiber on their plate.

Sugar

Sugar is everywhere in kids' diets. One study found that nearly half of kids eat sugary baked goods like cookies and cakes multiple times per week, and over 70% drink sugary sodas three times a week (4).

While sugar doesn’t always cause hyperactivity (aka the “sugar rush”), it can lead to big fluctuations in blood sugar which means more crankiness, more mood swings, and lower appetite for nutrient-dense foods. 

Too much sugar can also crowd out fiber and disrupt gut bacteria, both of which are important for healthy digestion (6).

Ultra- Processed Foods

Ultra-processed foods are those that have been changed significantly from their original form and often are high in preservatives, low in fibers, and high in fat. This combination is not good for the ecosystem of bacteria in the gut and overall GI health because they don’t feed any good bacteria. 

There’s even evidence that kids who eat more unprocessed or minimally processed foods have better brain development scores (4).

Meal Timing and Grazing

All-day snacking can throw off your toddler’s hunger and fullness cues, blood sugar rhythms, and regular pooping patterns leading to both crankiness and constipation.

One reason your little one is “always hungry” is they’re using food as emotional regulation rather than filling hunger. Studies show that kids who do this might have a more difficult time handling negative emotions and stress (7). 

Having set meal and snack schedules can help your toddler regulate their hunger and fullness, increase predictability to help moderate behavior, and can even stimulate good digestion long term.

Summary

A toddler’s poop and mood might feel like mysteries, but food is one tool that can help you support both. Paying attention to fiber, hydration, balanced meals, and limiting ultra-processed and sugary foods can go a long way in helping your kiddo feel their best inside and out.