You've heard the recommendations before: Like all foods, you should eat fat in moderation. But with the rising popularity of low-carb, high-fat diets like keto, you may be wondering how much is too much, and what the dangers of a high-fat diet might be.
Too much fat in your diet can cause a range of serious problems, including metabolic syndrome, cardiovascular disease and gastrointestinal issues. But dietary fat is also a necessary and healthy nutrient that supports a wide range of bodily functions.
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In the end, whether or not you're consuming too much fat comes down to the type of fat you're eating.
Too much fat in your diet may lead to health complications such as cardiovascular disease, metabolic syndrome or gastrointestinal issues.
Dangers of Eating Too Much Fat
Excessive consumption of fat is bad for your health. Regularly eating too much fat in your diet can result in problems like:
- Weight gain and obesity
- Heart disease and related issues, like high blood pressure
- High blood cholesterol levels and triglyceride levels
- Metabolic syndrome
- Type 2 diabetes
- Insulin resistance
- Fatty liver disease
- Neurodevelopmental issues for children and neurological problems in adults
- Gastrointestinal problems, which can also cause issues with the immune system and inflammation
- Increased risk of age-related vision loss
The health risks of eating too much fat are typically associated with the consumption of unhealthy fats. Fast foods, refined foods and processed foods, which are very popular in Western diets, are full of unhealthy fats.
According to an April 2018 paper in the American Journal of Lifestyle Medicine, at least 71 percent of Americans have overweight or obesity. Many of these people have other health issues, like prediabetes or gastrointestinal inflammation.
Many of the dangers of eating too much fat start with minor issues — like weight gain, digestive problems, high blood pressure and high cholesterol. However, these problems can often be mediated by simply eating a healthier diet. In many cases, you don't even need to reduce your fat intake — you simply need to make sure you're consuming healthier fats.
Read more: 16 Foods Dietitians Won't Touch
Healthy vs. Unhealthy Fats
Although fat has a bad reputation, dietary fats are not all created equal. In fact, some fats are healthy and even considered to be essential for your health. There are several types of fats that you might consume on a daily basis:
- Monounsaturated fatty acids: Monounsaturated fats, like oleic acid and other omega-9 fatty acids, can be found in plant-based cooking oils and other fatty plant-based foods, like avocado or coconut. You can also find these fats in some animal products. These fats are generally considered to be healthy but aren't usually considered essential.
- Polyunsaturated fatty acids: Polyunsaturated fats, like omega-3 and omega-6 fatty acids, can be found in a variety of foods like vegetables and marine products. These are very healthy fats that play a role in the health of various different parts of your body, including your immune system, nervous system and cardiovascular system. They can also help lower cholesterol and triglyceride levels and certain types are even used to treat health issues.
- Saturated fats: Saturated fats are found in animal products like meat, eggs and dairy products, some oils and processed foods. These fats are OK to consume in moderation but shouldn't be eaten in excess. Unlike healthier, unsaturated fats, too much saturated fat can contribute to increased cholesterol levels and other health issues.
- Trans fats: Trans fats come from hydrogenated oils, processed foods and baked goods. These are technically the worst fats for your health, as even small amounts can increase your risk of heart disease and other problems. They can even affect neurodevelopment. However, certain trans fats with slightly different chemical bonds, like conjugated linoleic acid, are safe and healthy.
According to the Food and Drug Administration, people who eat the standard 2,000-calorie diet should consume no more than 65 grams of fat each day. Most of these fats should be healthy fats, like monounsaturated and polyunsaturated fatty acids.
Up to 20 grams of this amount can come from saturated fat. However, other authorities, like the American Heart Association, recommend consuming less (no more than 13 grams a day on a 2,000-calorie diet).
There's no limitation on trans fat consumption — you should just try to eat as little as possible. As few as 5 grams per day has been shown to have a negative affect on your health.
Read more: 18 Fat-Rich Foods That Are Good for You
Eating a High-Fat Diet
You've probably heard of high-fat diets (also known as low-carbohydrate diets). When you follow a low-carbohydrate, high-fat diet like the Atkins or ketogenic diets, you're consuming about 20 grams of carbohydrates per day. This means that you're mainly eating fat — in fact, fat is 70 to 80 percent of your diet.
Given that there are so many dangers associated with eating too much fat, you might be surprised that high-fat diets can actually offer health benefits. In fact, high-fat diets have been shown to help people:
- Lose weight
- Reduce high cholesterol and improve cardiovascular health
- Improve their mental and neurological health
- Manage and even reverse Type 2 diabetes
- Manage epilepsy that can't be fully treated with medications
High-fat diets are even able to reverse some of the issues associated with excessive consumption of unhealthy fats. This means that it's possible to eat a large amount of fat on a regular basis and still be healthy.
How Healthy High-Fat Diets Work
Although these diets promote consumption of fat, people who follow them end up avoiding the vast majority of fast foods, refined foods and processed foods and don't eat many trans fats as a consequence. This is because high-fat diets focus on the consumption of large amounts of fats but few carbohydrates and only moderate amounts of protein. This means that even foods like fried chicken, which you might think would fill the bill, aren't suitable because they're breaded with high-carbohydrate grain products.
Ketogenic diets also prevent you from consuming excessive amounts of animal products, as you're only consuming moderate amounts of protein. This means that while you may be consuming saturated fat on a daily basis, it's unlikely that you'd consume excessive amounts.
The fat you consume should typically come from foods rich in monounsaturated and polyunsaturated fats, like fatty fish, extra-virgin olive oil and fatty plant-based products, like avocado or coconut. Because carbohydrates are limited (other than healthy carbohydrates from fiber, which are good for your digestive system), people on healthy, high-fat diets typically eat carbohydrates in the form of vegetables or fruits with low sugar content, like raspberries.
- Indian Journal of Medical Research: "Ketogenic Diets: Boon or Bane?"
- Advanced Pharmaceutical Bulletin: "Ketogenic Diet Provides Neuroprotective Effects Against Ischemic Stroke Neuronal Damages"
- Nutrients: "Effects of Ketogenic Diets on Cardiovascular Risk Factors: Evidence From Animal and Human Studies"
- Journal of Clinical Neurology: "Efficacy of and Patient Compliance With a Ketogenic Diet in Adults With Intractable Epilepsy: A Meta-Analysis"
- American Heart Association: "Saturated Fat"
- Food and Drug Administration: "Saturated Fat"
- Food and Drug Administration: "Total Fat"
- Review of Food Science and Technology: "Conjugated Linoleic Acid: Potential Health Benefits as a Functional Food Ingredient"
- BMJ Open: "Tracing Artificial Trans Fat in Popular Foods in Europe: A Market Basket Investigation"
- American Heart Association: "The Facts on Fats Infographic"
- National Institutes of Health: "Omega-3 Fatty Acids Fact Sheet for Health Professionals"
- Lipids in Health and Disease: "Monounsaturated Fatty Acids, Olive Oil and Health Status: A Systematic Review and Meta-Analysis of Cohort Studies"
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- The ISME Journal: "Modulation of Gut Microbiota During Probiotic-Mediated Attenuation of Metabolic Syndrome in High Fat Diet-Fed Mice"
- Nature: "High-Fat Diet-Mediated Dysbiosis Promotes Intestinal Carcinogenesis Independent of Obesity"
- Mayo Clinic: "Nonalcoholic Fatty Liver Disease"
- British Journal of Ophthalmology: "Diet patterns and the incidence of age-related macular degeneration in the Atherosclerosis Risk in Communities (ARIC) study"