Are Your Overnight Oats Making You Fat?

Yup, those yummy looking overnight oats might not be as healthy as you think. Overnight oats are all the rage ever since the mason jar trend came about. Everyone loves it because it’s healthy, easy to prepare, the most that you need to do is chop some fruits and you can even arrange it to look aesthetically appealing for social media.

Overnight oats are made up of oats, milk, fruit and nuts, the perfect combo for a healthy meal right? How can it be fattening?

For starters, not everyone likes eating oats. In its plain form with no additions except water to cook it, it is lumpy, chewy and bland. So, those who don’t like it might force themselves to eat it because oats have the health halo effect, where you eat it because everyone says it is healthy. Somehow, that can cause a backfire when you try to cover the taste of the oats by adding more sugar, fruits and other sweet stuff to make eating it more bearable.

So what are the other mistakes that you might be making with your overnight oats that might be making it less healthy? Here’s a break down:

Which oats are you using?

type of oats

Oats are healthy, no doubt about that. It contains a soluble fiber called beta-gluten which helps to lower bad cholesterol such as LDL and regulate your blood sugar levels [1]. However, not all oats are made equal. Here are the oats that you can find in the market:

  • Oat groats: Whole oat kernels that are hulled and toasted. Will take a long time to cook and is uncommon. It has the lowest GI too.
  • Steel-cut (Irish) oats: Oat groats that have passed through steel blades which slices them into smaller pieces so it cooks faster (about 15- 20 minutes). Low GI.
  • Old-fashioned oats: Oat groats that are steamed and flattened to become flakes. Cooks in 10- 15 minutes. Low GI.
  • Quick-cooking oats: Same process as old-fashioned oats, except they are cut finely before rolling so the flakes are smaller. Cooks faster than old-fashioned oats. Higher GI.
  • Instant oatmeal: Groats that are finely chopped, flattened, pre-cooked, and dehydrated. Mostly found in individual packets with additional sugar and salt. The worst kind of oats you can use. Higher GI.
  • Scottish oats: The same as Irish oats but they are grounded into smaller pieces, like the size of a sesame seed.  Scottish oats are creamier and more porridge-like than steel-cut oats. But it’s not common here. Low GI.

Different oats have different cooking time, texture and glycemic index (GI). GI relates to the speed of the carbohydrate in your food increase your blood sugar levels [2]. The higher the GI, the higher your blood sugar levels will be and food will be digested faster. Which is not good because it will cause a spike in your blood sugar levels and you will be hungry the next hour.

The lower the GI, the slower your blood sugar level will increase and your food will digest slower. Steel-cut oats, old-fashioned rolled oats and Scottish oats have low GI of less than 55 while, quick and instant oats have a high GI between 56-69 [3].

Try going for for steel-cut or old-fashioned rolled oats the next time you make overnight oats or hot oatmeal. Portion it to 1/2- 1/4 cup of uncooked oats for one person per jar. These oats will make you feel fuller for a longer time too so it could help you control your hunger throughout the day.

There are only minor differences in the calorie count between the oat variety, at about 150 calories and above for half a cup of uncooked oats. The liquid you soak the oats in will affect the calorie count of your overnight oats too. More on that in the coming section.

Are you using the right milk?

milk types

It’s good to add milk to make the oats creamier and it gives your oats an extra dose of calcium and protein [4]. If you are lactose-intolerant, you can use milk substitutes like almond milk and rice milk. Keep in mind though that milk has calories too. Depending on the type of milk you pick, your overnight oats could be either helping or sabotaging your weight-loss plans. Take a look at the different variety of milks that you can add into your jar:

milk calories chart

Most recipes would call for half cup of milk and another half cup of yogurt to make it ‘healthier’ and balance the richness of oats. Depending on the yogurt that you go for, it affects the calorie count too. Plain low-fat (72 cal) or fat-free yogurt (60 cal) is the best option as it doesn’t have much sugar in it so less calories. Beware of the fruit yogurts (strawberry yogurt, peach yogurt, etc) as those are known to be packed with sugar.

If you’re watching your calorie-intake, you might want to replace full-cream, flavoured milk and sweetened yogurt with low-cal options such as low-fat milk, unsweetened milk, unsweetened nut milk, plain fat-free yogurt or even water.

Are you dressing it too sweet?

honey and brown sugar

Brown sugar, honey, maple syrup, molasses and more add a sweet touch of taste and calories to your oats. 1 tablespoon of sugar will rack up your calorie-count by 96 calories. And that’s just for white sugar, what about the rest?

sweeteners sugars calories chart

Most people like things sweet, and would add more than a tablespoon of saccharine goodness into their overnight oats. That in itself is already more than 100 calories. If possible, try to keep the sweeteners to a minimal. Instead, try adding a teaspoon of cinnamon, pure vanilla essence, or pure cocoa powder to give your overnight oats more depth in flavour instead of going the sugary route [5].

What additional toppings are you adding into your overnight oats?

dried fruits and nuts

Adding toppings is the last step and it’s when most of us would be extra generous with the nuts and dried fruits. After all, nuts and fruits are healthy, aren’t they? True, nuts can help lower bad cholesterol and is rich in Omega-3 fatty acids, but nuts are also made of 80% fat so even a handful of them will provide a lot of calories [6]. For those of you watching your calorie intake, try being less heavy-handed on the nuts. Go for the raw and dry roasted variety instead of the sugar and salt covered nuts for a lower-calorie option.

nuts calorie chart

Dried fruits are great because they have a longer shelf-life, portability and sometimes their nutrients are more concentrated [7]. Generally, dried fruits are healthy dehydrated fruits but most of the dried fruit variety in the market have been processed with additives and sugar so processed dried fruit are not so healthy. Even so, dried fruits with no additives should be added sparingly too because they still contain more calories than fresh fruits [8].

dried fruits calories chart

The best solution is to top your overnight oats with fresh or frozen fruits which has less calories than the dried variety. Your fruits will last longer if you freeze it too [9]. Don’t forget, you still have to adjust the amount of the fruit unless you are not so worried about extra sugars. Be creative and bring out your inner food stylist by decorating your overnight oats with fresh apples, bananas, strawberries and many more bright coloured fruits to make it look Pinterest-worthy.

Altogether, your overnight oats could be racking up to 400 calories above which is higher than a plate of nasi lemakSo, pilling on nuts and dried fruits is not a smart move if you are aiming to lose weight. Here are some tips that we have summarized for you to take note the next time you are prepping your overnight oats:

The Do’s & Don’ts of Overnight Oats

  • Do go for steel-cut and old-fashioned rolled oats.
  • Do soak your oats with water, low-fat milk, unsweetened milk, nut milk, or plain unsweetened yogurt.
  • Don’t add too much sugar, honey, or sweeteners. Don’t add any sweetener at all if you can handle the blandness.
  • Do control the amount of dried fruits, nuts and other toppings that you add on top of your overnight oats.
  • Adjust the amount of ingredients to your liking and dig in the next morning! 🙂

We’re not saying overnight oats are bad for you, it’s pretty healthy compared to our typical local breakfasts. However, too much of a good thing can also be bad for you. The next time you are prepping it, you can be more mindful on what and how much you are putting into your jar. Controlling the amount of sweet, calorie-laden stuff in your overnight oats will make it healthier.

If you are one of those rare people who can have their overnight oats plain with no add-ons, we salute you! Even we are learning to reduce the amount of add-ons that we usually add into our oats. But if you are not a fan of oats at all, there are other ways for you to get your soluble fiber fix from fresh fruits and vegetables!


How do you make your overnight oats? Feel free to share here or on our Facebook page!

Sources: Diet Rebel, The GI Diet Club, Livestrong, Quick and Dirty Tips, About Health, SF Gate,, Calorie King, Pop Sugar, Fat Secret, Healthline, Mayo Clinic

2 thoughts on “Are Your Overnight Oats Making You Fat?”

  1. David

    Hello, nice article! Can you let us know where can we get steel cut oats in Malaysia? It’s pretty rare to see them in any supermarket. Thanks!

  2. Betty

    Great information, thanks!!!

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