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Does Eating Fat Make You Fat?


Since fat contains more calories per gram compared to carbs and protein, a lot of people fear fat, especially if they’re trying to lose weight.

But does eating fat make you fat? Not necessarily.

In fact, the deeply held belief that dietary fat equals weight gain has influenced individuals worldwide to consume excessive amounts of carbohydrates, which contributed to the obesity epidemic. (*).

Once we understand that fat loss (and more importantly health) isn’t a simple equation of calories in versus calories out, we can make better food choices.

Here’s more about the roles of healthy fats in your body, why dietary fat doesn’t make you fat, and the difference between good fats and bad fats.

Eat Fat, Get Fat?

The idea that fat makes you fat actually started in the 1950s with Ancel Keys, an American physiologist who pinned heart disease on a person’s diet. He conducted a large study showing that eating higher amounts of fat lead to heart disease. But what he didn’t reveal was the fact that the countries that ate higher amounts of fat also ate more sugar.

Unfortunately, his theory made the whole world believe that fat is responsible for cardiovascular disease and obesity. Because of this, we avoid fats in general, such as eggs, avocados, fatty meats, red meat, butter, cheese, and nuts.

These are sources of essential dietary fats, saturated fats, and monounsaturated fats packed with nutrients and make us feel satiated — on top of helping us reach a fat-adapted state on the keto diet.

Along with eating less fat, people consumed more carbohydrates to meet their energy needs. Food manufacturers also replaced fat with high-sugar ingredients to enhance the taste of food.

(Nowadays, we also see a rise in the use of vegetable and seed oils like canola oil, corn oil, and soybean oil in processed foods. These contain trans fats, which are the worst fats because they drive inflammation and disease.) 

The Role of Essential Body Fats

Essential body fats are exactly what they are. You need these fats in your body to function properly. These are the fats found in your bone marrow and vital organs, such as your lungs, heart, kidney spleen, and central nervous system.

Their roles range from temperature regulation to hormone regulation. For males, essential storage fat is around 2%. For females, it’s around 12% (*). Values above this can be considered as non-essential fat.

However, according to the American Council on Exercise, you can have up to 24% body fat, which is still considered “Acceptable” for men, and up to 31% for women (*). Beyond these percentages, a person is obese.

It all comes down to one thing: You need a healthy body fat percentage to function at your best, but having too much stored fat — visceral fat in particular — is associated with health problems like type 2 diabetes, heart disease, stroke, and cancer (*).

Moreover, study shows that an excessive intake of refined carbohydrates and added sugar increases your risk for obesity, plus it speeds up aging (*).

Fat Consumption Does Not Cause Weight Gain

The real key to a sustainable and healthy weight loss is to eat fewer carbs and more healthy fats in your diet. While many people turn to low-fat diets to lower their levels of body fat, several studies demonstrate that going low-carb is the better choice.

For example, a 6-month study done on severely obese men and women found that those who were assigned to the low-carb diet group (which also didn’t restrict total fat intake) ended up losing more weight than the low-fat diet group. Furthermore, the low-carb diet group saw a great decrease in their triglyceride and fasting blood glucose levels (*).

Ultimately, getting most of energy from carbs is going to increase your likelihood to gain weight. This is explained by the carbohydrate insulin model (CIM) of obesity, which explains that high glycemic load carbohydrates lead to hormonal changes in your body that cause it to store more fat and increase feelings of hunger. Large amounts of starchy foods — such as bread, rice, pasta, and cereals — increases postprandial insulin levels. Insulin is an important factor when it comes to gaining weight as the calories you eat get deposited into your fat cells (*).

This goes to show that losing weight isn’t about simply creating a calorie deficit, which is often done by reducing fat. Instead, people ought to focus more on obtaining their calories from the right foods — including quality fats from both animal and plant sources.

Later in this article, we’re going to show you the difference between the best and worst fats. But, for now, here’s more about the benefits of dietary fat for weight loss and optimal health.

Our Body Needs Fat for Optimal Function

Dietary fat is an important part of your nutrition, so you can’t really ignore it, especially if you want to fight obesity and promote good health. So, why does fat matter?

The main role of dietary fat is to provide your body with energy. Each gram of fat has 9 calories, whereas protein and carbs have 4 calories each per gram. This is why, on a low-carbohydrate or keto diet, you normally replace carbs with fat as your energy source. Reducing carbs to less than 50 grams on keto allows your body to enter a catabolic state in which insulin is reduced and you enter ketosis (*).

You also need dietary fat in order to absorb vitamins A, D, E, and K. These are called fat-soluble vitamins, meaning that they’re much better absorbed by your body in the presence of fat. Getting these vitamins in adequate amounts is necessary for immune function, hair growth, bone maintenance, and protection from free radicals (*).

Did you know that fat can keep you fuller for longer? Studies show that unsaturated fats — extra virgin olive oil, avocados, eggs, salmon, mackerel, and tuna — promote satiety, thereby reducing your food intake and helping with weight loss (* , *).

Fat is also good for the brain. As the fattiest organ in the human body (60-70% of the brain is made of fat), it makes sense to nourish our bodies with fat. Research finds that essential dietary fats, particularly omega-3s, are one of the most crucial molecules for your brain’s performance (*). In addition to omega-3s, your brain also thrives on saturated fats, which are found in meat, dairy, nuts, and butter (*).

Optimal hormone health results from an adequate intake of dietary fat. This is why eating a low-fat diet often messes up with women’s hormones. Remember that fats serve as the “building blocks” for the sex hormones estrogen, progesterone, and testosterone. Eliminating or reducing fat in favor of carbs can bombard your body with sugar, which disrupts your hormones.

As long as you get enough of the right fats and you’re not overly restricting your calories, you’ll be able to make progress towards your weight loss goals.

Different Types of Fats Have Different Effects on Our Body

No matter your diet, you should always aim to consume fats from unprocessed or minimally processed foods. In contrast, highly processed foods contain high amounts of trans fats on top of added sugar, artificial colorings, and flavor enhancers, which are all bad for your health.

Good Fats

  • Saturated fat: Contrary to popular belief, saturated fat has no effect on a person’s risk of getting heart disease (*). But do saturated fat cause weight gain? A study says otherwise. Based on the results, consuming saturated fat correlates with lower rates of obesity, high blood pressure, and diabetes (*).
  • Omega-3 fats: These fats are abundant in fatty fish, such as salmon, sardines, mackerel, herring, and tuna. A study on individuals following a keto diet found that consumine omega-3s led to decreased triglycerides (which cause arteries to harden) and insulin levels (*).
  • Monounsaturated fats: These fats are found in olive oil and avocados, and they’ve been shown to help improve insulin sensitivity and blood sugar control (* , *).

Bad Fats

  • Artificial trans fats: Formed by adding hydrogen to vegetable oil, these artificial fats are often found in margarine, traditional baked goods (muffins, pies, cakes) unless keto-friendly and homemade, potato chips, pizza dough, and non-dairy coffee creamers.
  • Omega-6 fats: These fats are beneficial only in small amounts. The problem is that a lot of people consume more omega-6 than they need from inflammatory vegetable oils. These harmful oils include canola oil, corn oil, sunflower oil, safflower oil, and soybean oil. Unfortunately, a high omega-6 consumption increases your risk of obesity, heart disease, nonalcoholic fatty liver disease (NAFLD), and Alzheimer’s (*).

Recommended Daily Fat Intake

How much fat should you include in your diet? Those on a very low-carb keto diet should get 60-70% of their calories from fat. For someone who consumes 1,500 calories per day, dietary fat would be around 100-117 grams. This can be met through healthy foods, such as avocados, eggs, grass-fed beef, and fatty fish. Snacking on nuts and zero sugar keto-friendly nut butters also satisfies your fat needs.

If you don’t know your personal fat macros yet, use our free keto macro calculator. Simply input your information (age, activity level, fat loss goal) and we’ll send you your results.

The Bottom Line

If you’re trying to lose weight, and more importantly reduce visceral fat, research suggests reducing dietary fat is not the solution.

Eating more fat while lowering your overall carbohydrate intake — the keto diet being one strategy — boosts fitness, improves your health markers (blood glucose levels, cholesterol, blood pressure), and puts you at a metabolic advantage.

Thinking of optimizing your diet? Perhaps it’s time to approach fat loss from a different mindset.

19 References

American Society for Nutrition. Scientists Claim that Overeating Is Not the Primary Cause of Obesity. 2021 September 13

Flynn et al. How Much Fat is Needed?. 2021 June 17

ACE. Percent Body Fat Norms for Men and Women.

Shuster A et al. The clinical importance of visceral adiposity: a critical review of methods for visceral adipose tissue analysis. 2012 January

Kroemer G et al. Carbotoxicity—Noxious Effects of Carbohydrates. 2019 October 18

Samaha F et al. A Low-Carbohydrate as Compared with a Low-Fat Diet in Severe Obesity. 2003 May 22

Ludwig D et al. The Carbohydrate-Insulin Model of Obesity: Beyond ‘Calories In, Calories Out’. 2019 August 1

Masood W et al. Ketogenic Diet. 2022 June 11

Meydani M et al. Intestinal Absorption of Fat-Soluble Vitamins.

Albertsson C. Fat-Rich Food Palatability and Appetite Regulation.

Maljaars J et al. Effect of fat saturation on satiety, hormone release, and food intake. 2009 February 18

Chang C et al. Essential fatty acids and human brain. 2009 December

Kangas B. New Research Finds Saturated Fats Can Lower Change of Cognitive Function Over Time.

Steur M et al. Dietary Fatty Acids, Macronutrient Substitutions, Food Sources and Incidence of Coronary Heart Disease: Findings From the EPIC-CVD Case-Cohort Study Across Nine European Countries. 2021 November 19

Gribbin S et al. Association of carbohydrate and saturated fat intake with cardiovascular disease and mortality in Australian women.

Paoli A et al. Effects of n-3 Polyunsaturated Fatty Acids (ω-3) Supplementation on Some Cardiovascular Risk Factors with a Ketogenic Mediterranean Diet. 2015 February 13

Riccardi G et al. Dietary fat, insulin sensitivity and the metabolic syndrome. 2004 August

Paniagua J et al. A MUFA-rich diet improves posprandial glucose, lipid and GLP-1 responses in insulin-resistant subjects. 2007 October

Patterson E et al. Health Implications of High Dietary Omega-6 Polyunsaturated Fatty Acids. 2012 April 5


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