How to Make Overnight Oats, According to This Nutritionist

Updated: Jan. 04, 2021

Dietitian and plant-based diet specialist Cynthia Sass shares how to make overnight oats, plus her unique power green oats recipe that delivers nutrients and vibrant color to start your day.

How to make overnight oats

Overnight oats have exploded in popularity, and for good reason. This simple, nourishing breakfast (or snack) can be made ahead to grab and go, or enjoy leisurely. A chilled twist on traditional warm oatmeal, overnight oats are a hearty alternative to a breakfast smoothie, and can be prepared in a variety of ways.

I’ve seen versions that are loaded up with too much added sugar, or piled with enough oats and add-ins to account for two meals worth of calories. To keep it balanced, I have a few simple strategies for how to build the best bowl.

The first step is to incorporate vegetables. It may seem unconventional, but some veggies, including zucchini, chopped kale, and even cauliflower, pair perfectly with sweet ingredients, like fruit and cinnamon. This addition also adds nutrients and fiber, and can displace a larger portion of oats, to reduce the overall carb content.

Next, bolster your oats with lean protein. My go-to is plain, unsweetened plant-based protein powder. A quarter cup, which can easily provide 20 grams of protein, adds a rich texture, and helps boost post-meal satiety, according to a study published in 2017 in Food Hydrocolloids.

I love a bit of crunch, so I opt for nuts to add healthy fat. But if you’re craving a creamy comfort-food feel, you can reach for nut butter instead. The rolled oats and fruit provide nutrient-rich carbs to round out the macronutrient content of this meal, and the portions are just enough to energize you all morning long.

overnight oatsCourtesy Cynthia Sass, MPH, MA, RD, CSSD

What are the ingredients in overnight oats?

My recipe below harnesses the power of three green plants—zucchini, kiwi, and pistachios—to pack your overnight oats with nutrients and vibrant color. Here’s the lowdown on each ingredient.


The main attraction, oats are a fiber– and antioxidant-rich whole grain with a number of health benefits, including cholesterol reduction, blood sugar regulation, weight management, and support for immune function and gut health, according to a study published in 2020 in Practical Diabetes. While oats are naturally gluten-free, some are processed alongside rye or barley, two grains that do contain gluten, which can result in cross-contamination. If you need to steer clear of gluten look for oats specifically labeled gluten-free.

Pea protein

I chose pea protein powder, made from split peas, but other good options include protein made from sprouted brown rice, pumpkin seeds, or almonds.


In addition to fiber, bananas provide vitamin C, energy-supporting B vitamins, and blood pressure-regulating potassium.


Zucchini is also rich in vitamin C, B vitamins, and potassium. And it’s filling, for less than 35 calories per medium zucchini.


Cinnamon adds flavor, plus compounds that have antioxidant, anti-inflammatory, anti-diabetic, antimicrobial, and anticancer effects, according to a study published in a 2016 issue of Advances in Experimental Medicine and Biology.

Maple syrup

I chose maple syrup as the sweetener, due to its flavor and nutrients. A study published in Pharmaceutical Biology, for instance, found 24 types of antioxidants in maple syrup. It also packs a healthy dose of manganese, a mineral that supports bone health, collagen production, and wound healing. (Here’s a full run-down on maple syrup nutrition.)


According to a study published in 2017 in the journal Natural Products Research, pistachios contain the highest levels of potassium and anti-inflammatory antioxidants compared to other nuts. Their consumption is also linked to improved heart health, weight loss, and better blood glucose control.


Just one kiwi provides over 100 percent of the Daily Value for vitamin C, in addition to fiber, potassium, and bone-supporting vitamin K.

Power Green Overnight Oats

Serves one


¼ cup dry old-fashioned rolled oats

¼ cup plain, unsweetened plant protein powder

¾ cup filtered very warm (not boiling) water

½ small ripe banana, mashed

½ cup shredded raw zucchini

1 tbsp. pure maple syrup

1/2 tsp. plus one dash cinnamon

¼ cup shelled pistachios, divided

1 kiwi, peeled and sliced


In a small bowl mix the dry oats with the protein powder to combine thoroughly. Slowly add the water and stir well to avoid clumping. Fold in the banana, zucchini, maple syrup, half teaspoon of cinnamon, and half of the pistachios.

Transfer half of the mixture to a mason jar, arrange the kiwi slices along the sides of the jar, and fill the jar with the remaining mixture. Garnish the top with the dash of cinnamon and remaining pistachios. Refrigerate overnight.

You can double or triple the recipe to make two or three servings. And there are countless mix-and-match combos to make versions that satisfy your preferences. Not a fan of kiwi? Replace it with green apple, or any fruit of your choice. Allergic to nuts? Swap them for pumpkin seeds. Chocolate craving? Add chopped dark chocolate or cocoa powder. The combinations are endless.