Editor’s Note: This post was updated on August 14, 2025, for accuracy and comprehensiveness. It was originally published on March 3, 2016.

Does eating fat make you fat? It’s a common and often misunderstood question in modern nutrition. The short answer? No, eating fat doesn’t automatically make you gain weight. In fact, healthy fats are essential to your body’s function, and the real issue lies in overall calorie intake, not fat itself.

So why do so many people still believe that fat is the enemy?

This article explores the roots of that misconception and clears up what science actually says about fat, weight gain, and metabolism.

Where the “Fat Makes You Fat” Myth Came From

If you went to primary school in the 90s, you probably remember this diagram from a nutrition class.

Released in the U.S. in 1992, the food pyramid was designed as an easy way for people to remember which foods they should be getting their calories from and the relative importance of each. Carbs were healthy and good, and so they formed the base; fats were bad and placed at the top. The fat category lumped everything together from healthy fats like Omega-3s and olive oil to saturated fats and sugar.

This concept helped trigger the fat-free craze. Although this concept seems pretty normal to us now, at the time in the late 1970s it was actually considered quite radical – so much so that then-president of the National Academy of Sciences, Philip Handler, described the proposed shift as a “vast nutritional experiment.” Essentially, the Dietary Guidelines suggested that people eat less fat and get more calories from bread, grains, rice, pasta, etc. This was intended to protect Americans from weight gain and heart disease. This is why the “high carb, low fat” diet seems familiar and normal to you, and probably why you think eating fat makes you fat.

What was the result of this recommendation?

Starting around 1977, when the low-fat guidelines were introduced, and especially after their official release in 1980, obesity rates in the U.S. began to rise — increasing by nearly 20%. People followed the advice to cut fat, but the result was the opposite of what was intended. Why? Because eating fat doesn’t necessarily make you fat. The real culprit is a caloric surplus — consuming more energy (calories) than your body uses.

While this might seem like a somewhat challenging thought, fat isn’t solely to blame for weight gain, and it’s not fair to even say it’s a major factor in weight gain. At fault is a confusing mishmash of terminology, the negative connotation of fat over the past generations, and a pesky little diagram that’s been imprinted in the minds of generations of Americans.

Let’s explore how fat developed a negative reputation and what the science says about it today.

Eating Fat Is Not the Same as Becoming Fat

One of the biggest reasons people believe that eating fat makes you fat is because we use the word fat to describe two very different things: the fat we eat (dietary fat) and the fat stored in our bodies (body fat). But these are not the same – and understanding the difference is key to making smart nutrition choices.

What Is Body Fat?

Body fat is more accurately called adipose tissue. It’s made up of fat cells (adipocytes) that store energy for your body to use when food or fuel is scarce. Contrary to how it’s often portrayed, body fat isn’t your enemy – it’s essential for survival. A person with 0% body fat wouldn’t be alive.

Extremely low body fat levels, such as those achieved by competitive bodybuilders, have been linked to hormonal imbalances, immune suppression, and performance decline. In one study, a male bodybuilder reduced his body fat from 14.8% to 4.5% for competition. The result? His body went into overdrive: testosterone dropped, cortisol rose, immune function weakened, mood and energy declined.

“Of note, many of the physiological changes observed including an elevation in cortisol, reduction in testosterone, reduction in immune function, alterations in mood status, and decreases in physical performance and maximal heart rate that occurred during the preparation period are consistent with markers of overtraining.” – Rossow, et al (2013)

This shows that body fat plays a vital biological role. Too much can create health problems — but too little can, too.

What Is Dietary Fat?

The fat you eat is dietary fat and is one of the three essential macronutrients your body can get energy from. When we talk about calories, we’re actually talking about some combination of the three macronutrients: carbohydrates, protein, and fat.

Let’s examine a standard nutrition label. What do you see?

Although they’re not labeled as such, you’ll see the three macronutrients listed there – which we’ve underlined – along with the grams of each. Each macronutrient contributes a certain numbers of calories to the total caloric content of the food.

• Carbohydrate: 4 calories per gram

• Protein: 4 calories per gram

• Fat: 9 calories per gram

Because fat is more calorie-dense, it’s easy to assume it’s worse for you, but that’s a misconception. Your body requires essential fatty acids, specifically linoleic acid (omega-6) and alpha-linolenic acid (omega-3), which it cannot synthesize on its own and must obtain through diet. These are called essential fatty acids and must come from your diet.

The truth? People used to eat more fat in the past, including healthy saturated and unsaturated fats, yet obesity rates were significantly lower than they are today. So if dietary fat doesn’t directly cause weight gain, what does?

What’s Actually Making You Fat?

The simple truth is this: you gain weight when you consume more calories than your body uses. That’s called being in a caloric surplus, and it’s the root cause of fat gain.

According to data, from 1970 to 2000, the average American’s daily calorie intake increased by 530 calories — a 24.5% jump. Not surprisingly, obesity rates rose sharply during that same period.

But Aren’t Carbs Lower in Calories Than Fat?

Yes – gram for gram, carbohydrates have only 4 calories, while fat contains 9. So it seems logical that switching from fat to carbs should reduce calorie intake. But that’s not how it worked in practice.

Here’s why: Some individuals consuming high-carbohydrate diets may experience reactive (postprandial) hypoglycemia, a condition where blood sugar drops significantly after meals, leading to feelings of fatigue or hunger. This can make people feel hungry again soon after a meal, even if they’ve eaten enough calories. That hunger often leads to more carb-heavy snacking: bread, crackers, rice, or sugar-rich foods. These are some of the most common foods that make you fat, not because of the carbs themselves, but because they’re easy to overeat.

By advising people to eat less fat and eat more carbohydrates, the government actually made the obesity problem far worse. Recognizing the sharp increase in obesity, the food pyramid was revised in 2005 and ultimately retired in 2011 in favor of what the USDA now calls “My Plate,” which gives people a much better visualization of the relative importance of each food category by showing roughly how much space each should take up on a plate.

To be clear, neither carbohydrates nor fats on their own cause you to gain weight – it’s just that you tend to eat more calories when your diet is focused on carbohydrates over fat. Being in a caloric surplus causes you to gain weight. A carb-heavy diet makes it very easy to be in a caloric surplus.

Should You Avoid Low-Fat Options?

If you’re smart about it, yes, but you still have to be careful.

While it’s very easy to eat extra calories on a carbohydrate-based diet, it’s also very easy to add on extra calories from a fat diet too. At 9 calories, fat is the most calorie-dense macronutrient by far. This means that if you’re looking to lose fat, the low-fat options are still fine choices – not because of their low fat content, mind you, but because of their lower caloric content.

The fat isn’t making you fat due to just being fat; it’s the extra calories from fat (as well as all the macronutrients) that is causing you to gain weight. What this means is, if you are responsible with your diet, you can choose foods that contain fat, guilt-free. You just need to be smart about your caloric intake throughout the entire day.

For example, if you prefer whole milk over 1% milk, you don’t need to feel guilty about choosing it. But you should know that whole milk has about 46% more calories, and that means you’ll need to adjust your calories elsewhere in your day to stay balanced. Most people can find a few extra carbs in their diet they could do without – whether it’s a sugary snack, an extra slice of bread, or a carb-heavy processed food.

Fat-Rich Foods List

Some fatty foods come with added sugars, refined carbs, or portion sizes that make it easy to overeat without realizing it. Others are nutrient-dense and genuinely beneficial to your health.

Let’s break down both types — not to label them “good” or “bad,” but to help you make more informed choices based on your goals.

Calorie-Dense Fatty Foods to Eat in Moderation

These are common “foods that make you fat” when they push you into a calorie surplus – often because they’re easy to overeat and don’t keep you full for long. They’re not “off-limits,” but they do require portion control, as their calorie density can lead to unintended overeating:

Fatty Foods That Fuel Your Body

These high-fat foods are nutrient-dense and satisfying, offering essential fatty acids and health benefits. Including them in a balanced diet can actually support weight loss and improve health, as long as you stay mindful of total calories.

Optimizing Your Diet

Ultimately, the only person who has any real influence on how you divide your nutrient intake/calorie limit is you.

A lot goes into planning, preparing, and following a diet. Trying to balance what you like to eat with what you should be eating to maintain a healthy weight and body composition can be tricky. Overly restrictive low-carbohydrate diets can be difficult to sustain and may not be necessary for long-term success. But if you want to make improvements, a diet lower in added sugars and saturated fats, while rich in unsaturated fats like omega-3s and monounsaturated fats, has been associated with improved heart and metabolic health.

When you have a good idea of what your individual caloric needs are, which you can learn by using a combination of your Basal Metabolic Rate and your activity level, this will become a lot easier.

Understanding how fat and the other macronutrients make up these calories will only further ease the problems with designing a nutrient-dense balanced diet. Remember, fat isn’t bad on its own. Focus on building a diet that you actually want to eat, keep it within a reasonable number of calories, add in more physical activity, bringing you closer to your goals than relying solely on packaged foods labeled ‘low fat’ or ‘reduced fat.’