Blog Categories


What Is The Oatmeal Diet, And Does It Work?


It seems like every year or so a new diet hits the scene claiming to be the miracle we’ve all been waiting for. These fad diets come and go like the wind, typically burning out quickly and leaving a lot of people confused (and probably hungry!).

Oats and other grains haven’t gotten a ton of hype over the last few years. Mostly due to the rise in popularity of low-carb and keto diets. So, it’s interesting to see a diet based solely on oatmeal to pop up in the nutrition world. 

Although low-carb and keto diets have some pretty amazing benefits, let’s take some time to explore the possible benefits and definite drawbacks of the newest craze: The Oatmeal Diet.

What Is The Oatmeal Diet?

Like the many diets that came before it, the oatmeal diet is the latest trend in weight loss that claims to help you shed four pounds in one week by structuring your diet around …you guessed it…oatmeal. 

Perhaps one of the blandest attempts at a crash diet yet, (are we just getting bored, or does the oatmeal council have a hand in this?), the oatmeal diet is broken down into three oatmeal-centric phases:

Phase 1

  • Phase one lasts one week.
  • During this week, dieters eat only oatmeal (½ cup serving size per meal), with the addition of skim milk if you want.
  • No instant oatmeal or granola allowed, only whole rolled oats. 
  • Calorie count should be between 900 to 1200 calories per day.

Phase 2

  • Phase two lasts 30 days.
  • During this phase, dieters continue to consume ½ cup of oatmeal with breakfast, lunch, and dinner, in addition to lean protein and vegetables for one meal per day.
  • Calories need to stay between 1000-1300 per day during this phase.

Phase 3

  • Phase 3 is basically your new lifestyle. Dieters are allowed to go back to their regular diet, but they still need to have one meal of oatmeal a day and one snack of oatmeal a day.
  • Dieters are also advised to continue to limit their intake of fats during this phase. 

What Can You Eat on the Oatmeal Diet?

It may seem obvious, but there are some details to consider with the Oatmeal Diet. First, there’s the main course. No granola or instant oats or flavored oats. Only whole, rolled oats allowed. A small amount of skim milk and some fruit is allowed with your “meal.”

Some sites say that non-fat or low-fat yogurt is also allowed as a side dish. Spices like cinnamon are allowed, but no sugar or fats.

Snacks can include raw nuts and veggies, but these must be added to your total calorie count for the day. Dinners can include lean protein like grilled chicken, fish, or turkey and vegetables. 

What Are The Health Benefits of The Oatmeal Diet?

It’s assumed that the only real benefit of severe caloric restriction is weight loss. But others report alleged health benefits like:

  • Weight loss
  • Curbed appetite due to oatmeal’s satiating effect
  • Increased fiber intake
  • Lowered cholesterol levels 

One thing is certain: you probably will lose weight if you restrict your caloric intake to 900-1300 calories per day. But that doesn’t mean this diet is good for you. Read on for some of the risks associated with the Oatmeal Diet and why you might want to choose another approach to health. 

Risks of the Oatmeal Diet

#1: Still Lacking Fiber

No one’s going to argue that oatmeal isn’t a good source of fiber. The thing is, during the first phase of this diet you’re still going to be severely lacking fiber. 

Why? Because you’re going to be severely lacking everything. 

During week one, you’ll be consuming a total of one and a half cups of oatmeal per day (broken down into three meals — so ½ cup per meal). You can add in some skim milk if you really want to treat yourself, but that won’t help you in the way of nutrition. 

The nutritional breakdown for one and a half cups of oatmeal looks like this[*]:

Calories: 450 calories

Fat: 7.5 grams 

Carbs: 81 grams

Dietary fiber: 12 grams

Protein: 15 grams 

With an average dietary guideline for around 25-35 grams of fiber per day, the first phase of this diet is struggling to provide even 50% of your daily needs. And as for phases two and three, aside from the “allowance” of fruit and vegetables, there are no guidelines to include more fiber-rich foods.

To be fair, some proponents of the diet say that you can include fresh fruit as a morning snack and raw vegetables during phase one as well. 

However, if you wanted to reach the very minimum RDI for fiber with additional fruit, you would need to consume something like two oranges, two peaches, and one apple every day in addition to your oatmeal[*][*][*].

The beneficial fiber claim just isn’t adding up. 

#2: Incredibly Low-Fat

Wait, is it 1990? If you thought the days of fear-mongering around fat were finally behind us, think again.

In the first phase of this diet, your fat intake will be around 7.5 grams per day, with guidelines to keep fat low throughout all three phases. 

Even on a non-low-carb meal plan, 7.5 grams per day is strikingly low. Guidelines from authorities like the Cleveland Clinic recommended fat intake to be about 20-35% of your daily calories[*]. 

From a keto perspective, this is still on the low side, but even that number would amount to around 44 to 77 grams of fat per day — of which 7.5 grams would only be a fraction. 

The idea that eating fat makes you fat is so archaic it’s almost offensive to have to argue this point, but let’s do it anyway. 

First of all, your body needs fat in order to maintain[*]:

  • Cell membrane function
  • Sex hormone production
  • Brain development
  • Nervous system function
  • Blood clotting
  • Inflammatory responses
  • Assimilation of fat-soluble nutrients like vitamin A,D,E, and K
  • Insulation to keep your organs safe and your body warm
  • Health of your hair, skin, and nails
  • And more 

You Need Healthy Fats

But coming strictly from a weight loss perspective, dietary fat plays a number of crucial roles, including:

  • In your intestines, dietary fat stimulates the hormone CCK, which then tells your brain that you don’t need more food and induces a sense of satiety[*].
  • Dietary fat has a high “thermic effect,” which means that it puts your metabolism to work and burns more calories as it’s being broken down[*].
  • Sufficient dietary fat is necessary to keep your metabolism high after weight loss to prevent weight regain. Conversely, a low-fat diet results in a diminished metabolism, and likely a rebound in weight gain[*].

Study after study comparing low-fat diets to high-fat diets show that high-fat approaches are more efficient and sustainable for weight loss. What’s more, many of these trials also note improvements in metabolic markers and blood lipids[*][*][*][*][*]

So, where does the idea that dietary fat makes you fat come from?

Interestingly, research shows that it’s the addition of sucrose (sugar) to fatty meals that’s most likely the culprit for dietary fat-induced weight gain — not the fat itself[*]. 

If only there were a diet that cuts carbs significantly… 

#3: Crash Diets Don’t Work

Crash diets, fad diets, whatever you want to call it — if you find a diet that’s meant to only last for a short time that’s your red flag. 

Sure, you may drop a few pounds on a diet consisting of 450 calories a day worth of oatmeal, but that weight isn’t going to stay off. And the reality of the situation is that in a calorie deficit of that nature you’re losing a lot of water weight, not necessarily fat[*]. 

But severe calorie restriction not only leaves you hungry and tired, but it can also cause harm to your metabolism. 

Research shows that when you drastically cut calories, it can lead to something called adaptive thermogenesis (AT). AT is your body’s way of conserving energy when you’re not giving it sufficient food. This conservation attempt results in a drop in your metabolic rate, making it much easier for you to regain any weight that was lost during your crash diet[*].

This is the entryway into the so-called “yo-yo diet” lifestyle, where you restrict for a while, feel great, gain it back, and restrict again. Of course, no one sets out to yo-yo diet, but once you get on that train, it can be hard to jump off. 

Beyond stubborn weight gain, calorie restriction and the subsequent yo-yo diet can also result in serious issues like high blood pressure, lowered HDL cholesterol, increased risk of heart disease and stroke, and the onset of metabolic syndrome[*][*]. 

#4: Lacks Protein

In the first week on the oatmeal diet, you’ll be consuming 15 grams of protein a day. With the RDA stating that for most people 0.75g/kg is the amount of protein you need for maintenance, this means that phase one of the oatmeal diet is perfect for a 45-pound human. In other words, this diet is ideal for a six-year old. 

Okay, so that’s just week one, what’s the big deal?

The big deal is that protein is by far the most important macronutrient when it comes to weight loss. Fat may play several crucial roles in weight maintenance, but it’s got nothing on protein.

To begin, the amino acids that makeup protein are essential building blocks for the muscles in your body. Muscle tissue is the most metabolically active tissue you’ve got — meaning it burns the most calories. Therefore, more protein equals more muscles, which equals more calories burned daily[*]. 

Furthermore, when you’re losing weight on any diet, some of that weight is going to come from your muscles. Research shows, however, that on high protein diets your body is able to conserve more lean muscle mass, which means that more weight loss is coming from fat instead of muscle[*]. 

But that’s not all.

Of all the macronutrients, protein is by far the most satiating and also has the highest thermic effect (i.e., it burns the most calories while being broken down). That means that when you consume a meal high in protein, you’ll get full faster, likely eat less and burn more calories than you would eating the same amount of food coming from carbs or fat[*]. 

But you know, eating the amount of protein required by a six-year old may work too. 

#5: There’s No Research To Support It

The world of nutrition research is constantly growing, with new studies and revelations being discovered every day. 

So why isn’t there any research on the oatmeal diet? Because it’s silly, that’s why. No self-respecting scientist is going to spend grant money trying to uncover the wonders of eating inordinate amounts of a single grain for several weeks. 

Luckily, there are plenty of research-backed ways to lower your weight and enhance your health. And among them, cutting carbs stands out as one of the most efficient and easy options to stick to[*][*][*].

#6: It’s Boring

Variety is the spice of life, and this diet is boring. Even though after week one, you’re allowed to consume somewhere between 500 and 800 calories of anything other than a bowl of oatmeal, that’s still incredibly restrictive from the perspective of anyone that enjoys food. 

Again, there are plenty of research-backed ways to lose weight sustainably without having to subject yourself to inordinate amounts of oatmeal. 

Choosing a diet that allows for variety is going to drastically increase your chances of success. 

Will You Lose Weight On The Oatmeal Diet?

So the question remains; will you lose weight on the oatmeal diet?

It’s very likely that within the first few weeks on this diet you’ll see a drop on the scale. However, that number is going to come mostly from water, and likely from muscle mass as well. 

Unfortunately, the chances of weight regain following a diet like this are very high. You’re not only subject to the yo-yo dieting game, but your metabolism will likely take a hit from the lack of protein. 

If you’re looking for a more reasonable approach, choose a diet protocol that conserves muscle mass and metabolism and results in slow and steady weight loss. 

The Takeaway

Eating oatmeal and other whole grains may come with some health benefits, but if you’re looking for a weight loss diet relying on carbs is not the way to go. 

A high-carb, low-calorie diet is more likely to send your body into blood sugar mayhem then fire up your metabolism. And even worse, diets like this tend to be the gateway to yo-yo dieting, which can result in serious metabolic damage. 

If you’re looking for weight loss, go the slow and steady route, and follow in the footsteps of those who have lost weight and kept it off. 

By far, the most satiating and effective way to drop pounds is to cut back on your carb intake. Following a ketogenic diet offers plenty of variety, flavor, and nutrients that help to support a strong metabolism and maintain lean muscle mass. And best of all — you’ll never get bored.


Join the Internet's largest keto newsletter

We'll send you articles, product guides, and exclusive offers customized to your goals.