Is Oatmeal Fattening? Why Oatmeal Can Make You Gain Weight

Is oatmeal fattening, or are oats good for weight loss? Many think eating oatmeal every day for breakfast is a surefire way to lose weight, but it could also end up making you gain weight.

Oatmeal is a breakfast favorite for many people. It’s filling, nutritious, and supposedly healthy. But is oatmeal indeed healthy for you? Or is it fattening? Oatmeal is low in calories and rich in fiber, but it also contains a lot of carbs.

Too many carbs and blood sugar spikes can lead to weight gain and belly fat. So is it possible that eating oatmeal in the morning makes you gain weight? Here you’ll discover why you might want to skip your morning oatmeal, as it could be causing you to pack on the pounds unknowingly.

In this blog post, we will explore the truth about oatmeal and answer these questions once and for all!

Does Oatmeal Make You Gain Weight

how fattening is oatmeal

Oatmeal, in some ways, can be beneficial for weight loss but can also make you gain weight. There are a lot of factors involved that can make it more likely you’ll gain or lose weight from eating oatmeal every day for breakfast.

First, oatmeal can be healthy due to its high fiber content. The fiber in oatmeal is beta glucan which is a soluble fiber. This fiber can help you feel full and reduce food cravings throughout the day. Oatmeal is also low in calories and fat and contains some protein and other vitamins and minerals.

But oatmeal is also high in carbs. For example, one cup of cooked oatmeal contains almost 30g of carbs. Eating a lot of carbs can cause blood sugar spikes, leading to insulin resistance and weight gain over time. The problem with oatmeal is that even though it’s a whole grain and complex carb, it’s still a high-carb food.

If you eat oatmeal for breakfast, you’ll probably be hungry again by mid-morning if you have a blood sugar crash. This can lead to snacking and overeating later in the day, which will cause weight gain. Oatmeal can also be fattening if you add too much sugar or toppings like dried fruit, milk, brown sugar, maple syrup, and honey.

Adding these toppings adds more calories, carbs, and sugar, which can cause weight gain. If you’re trying to lose weight, you should avoid eating oatmeal with these toppings. Instead, try eating oatmeal with protein like eggs or Greek yogurt to slow its absorption and boost protein.

How Oatmeal Can Make You Gain Weight

Now it’s thought that since oatmeal contains fiber, it would slow the absorption of the carbs by your digestive system, thus preventing a blood sugar and insulin spike. Rolled oats have a Glycemic Index (GI) score of 55 (low) and Glycemic Load (GL) of 10.8 (midrange).

The GI score tells you how much it can raise your blood sugar, while the GL score tells you how much it’ll increase your blood sugar plus the number of carbs in the food. So it’s a good idea to keep an eye on both scores to ensure you’ll keep your blood sugar and insulin levels in check.

On the surface level, the GI and GL scores for oatmeal don’t look too bad. But the truth is this isn’t a one-size-fits-all answer for everybody. So much will depend on your insulin sensitivity, gluten intolerance, and metabolic flexibility.

Up to 50% of Americans are undiagnosed diabetic or pre-diabetic, so eating a carb-rich meal isn’t the best choice. Sadly, many Americans eat a diet rich in carbs, sugars, starches, refined grains, processed foods, and inflammatory seed oils. Insulin resistance is a lot more prevalent, and there’s a good chance the average person won’t handle the carbs in oatmeal very well.

Oatmeal won’t be a good choice if you have gluten sensitivity or intolerance. Gluten intolerance has increased in recent years due to antibiotics, poor gut health, and eating processed foods that the body has trouble digesting. Pure oats are gluten-free but can quickly become contaminated with gluten during the farming and manufacturing process.

Your metabolic flexibility will also play a role. This is your body’s ability to use carbs and fat efficiently as a fuel source. You’re probably metabolically inflexible if you have trouble with your weight and quickly gain fat. Those with poor metabolic flexibility have trouble burning their fat stores for fuel and can become “sugar burners,” relying on carbs for energy. It’s then easy to overconsume carbs to the point that your body starts storing them as fat.

How to Prepare Oats for Weight Loss

What can make oatmeal fattening isn’t really the oats themselves but what you add to them. Most don’t eat plain oatmeal and instead add milk, fruit, sugar, honey, etc., to make it more palatable. These sugars and carbs on top of the oatmeal will increase its Glycemic Load even more, making it fattening.

Then with a higher Glycemic Load, you’ll experience a blood sugar crash after your body spikes insulin to counteract the high blood sugar. When your blood sugar crashes, you’ll not only feel tired and lethargic but also crave more sugars and carbs to bring yourself back up. This can put you on the roller coaster of blood sugar spikes and crashes for the rest of the day.

The trick with eating oatmeal for weight loss is to prepare it as plain as possible. Do not add milk, fruit, brown sugar, honey, etc., to sweeten it. Eating “naked carbs” is what is going to skyrocket your blood sugar and insulin. Instead, if you must add in some eggs or almond butter to have some protein and fats, that’ll slow its absorption.

Keep your serving size small. Oats might be considered low on the Glycemic Index, but once you start overeating, the Glycemic Load of the oatmeal will put you into dangerous territory. For example, one cup of cooked oats should be your max size per serving to keep the total content of the carbs manageable.

Do not go for the instant oatmeal since it usually contains pre-added sugars to sweeten it up. Instead, cook your own rolled oats or even better steel cut oats that contain more fiber and are even lower on the Glycemic Index.

Is Oatmeal Healthy for Breakfast?

Now even though oatmeal might not be the best choice for breakfast depending on your circumstances, it’s still healthier than a lot of other popular breakfast choices. For example, bagels, cereals, muffins, toast, fruit juice, waffles, pancakes, pastries, etc., are all way worse breakfast foods than plain oatmeal.

So it’ll be much preferable to have one cup of cooked steel cut oats than a bowl of Lucky Charms cereal. So if you’re used to eating one of those bad breakfast carb-rich foods above, switching to oatmeal (without added sugars or carbs) will be a much-preferred food choice if you’re trying to lose weight.

Then eating all those carbs for breakfast in your bowl of oatmeal should be burned off as fuel through movement. If you’re exercising or live an active lifestyle, you shouldn’t worry about too much. But if you’re sedentary and don’t often exercise, having a bunch of carbs first thing in the morning may not be the best choice, especially if you’re metabolically inflexible.

I personally recommend intermittent fasting in the morning and skipping breakfast entirely. Your body will have an easier time burning off your fat stores for fuel when it hasn’t had any quick burning sugars or calories coming in. Drink some coffee in the morning for its natural fat-burning effect and add in some C8-MCTs that trigger your body to burn fat stores for fuel. Use this MCT coffee creamer:

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Is Oatmeal Fattening at Night Before Bed

oatmeal before bed at night fattening

If there’s any time I’d advise against eating oatmeal it would be at night before bed. Eating those carbs will more likely be stored as fat if you just go to sleep. If you have to eat oatmeal, then it’s best earlier in the day when you’ll still be active, and it’ll be easier to burn them off.

But with that said, I know some really like to eat oatmeal at night. Eating one cup of plain steel cut oats is much better than a bowl of Cinnamon Toast Crunch or a pizza. So eating a little bit of plain oatmeal with some cinnamon sprinkled on top will be the lesser of the two evils if it helps to satisfy your craving.

I don’t like to eat oatmeal with milk at night or any other time of the day because milk contains sugars. Milk will cause your insulin levels to spike because it contains sugars. Skim or non-fat milk might sound like a better option, but when you take the fat out, you’ll be left with just the sugars. The fat in milk can help to slow the absorption. So if you have to add milk, go with whole milk but keep the serving size small with just a dollop. Oat milk isn’t a good choice since it can contain sugars and inflammatory seed oils.

So there are plenty of disadvantages to eating oatmeal at night, and it’s far from the best time to eat them, which is earlier in the day. But if you have to have oatmeal at night, keep it to one cup and don’t add any milk, sugars, fresh fruit (bananas included), maple syrup, or honey. Try adding some cinnamon to help slow the blood sugar spike after eating oatmeal.


At the end of the day, a small serving of plain oatmeal isn’t going to be fattening, especially if you’re insulin sensitive and are metabolic flexible. It’s usually all the milk, sugar, dried fruit, etc., that you add to the oatmeal that makes it fattening. Instant oatmeal should be avoided since these pre-mixed packets usually contain added sugars to sweeten them up.

Eating oatmeal every day isn’t the best choice if you’re not metabolically flexible. But if it satisfies your breakfast carb craving without eating a bagel and muffin, then it’ll definitely be the better choice. Oatmeal itself isn’t all that bad on the Glycemic Index, but the Glycemic Load can become a big problem when you start to eat too much, which is why you want to keep it at a cup maximum.

I personally don’t eat oatmeal anymore after I tried eating it after hearing all the health benefits. Despite not adding sugars, milk, or fruit, I had a blood sugar spike. I had trouble digesting it and would feel like junk for hours after eating it. I’m usually intermittent fasting in the morning, but if I do eat breakfast it’s low carb. Usually eggs, avocado, and nuts for the high protein and healthy fats.

Everybody is different, so it’ll be a good idea to pay attention to how you feel after eating it. If you feel great and don’t have any issues, then good for you to keep eating it. But if you experience any issues, it might be best to skip the oatmeal or it could be fattening.