Monounsaturated fats are healthy fats found in olive oil, avocados and certain nuts.
In fact, the evidence shows that monounsaturated fats have a number of health benefits.
They can help with weight loss, reduce the risk of heart disease and decrease inflammation.
This article will discuss monounsaturated fats and the scientific evidence behind their advantages.
There are a number of different types of fat in your diet, which vary in their chemical structure.
Unsaturated fats are those that have double bonds in their chemical structure.
Monounsaturated fatty acids, or MUFAs, are a type of unsaturated fat. “Mono,” meaning one, signifies that monounsaturated fats have only one double bond.
There are many different types of MUFAs. Oleic acid is the most common type, comprising around 90% of those found in the diet (1).
Other MUFAs include palmitoleic acid and vaccenic acid.
Many foods are high in MUFAs, but most consist of a combination of different fats. There are very few foods that contain only one type of fat.
For example, olive oil is very high in MUFAs and other types of fat.
Foods that are high in unsaturated fats, such as olive oil, are usually liquid at room temperature, whereas foods that are high in saturated fats, such as butter and coconut oil, are usually solid at room temperature.
These different fats affect health and disease differently. Monounsaturated fats, in particular, have been shown to have a number of health benefits (2).
Summary: Monounsaturated fats contain one double bond in their chemical structure and may have various health benefits.
All fats provide the same amount of energy — 9 calories per gram — while carbs and protein provide 4 calories per gram.
Therefore, reducing the amount of fat in your diet can be an effective way to reduce your calorie intake and lose weight.
However, a diet with moderate-to-high amounts of monounsaturated fats can also help with weight loss, as long as you aren’t eating more calories than you’re burning (3).
For example, one study of 124 people who were overweight or obese found that eating either a high-MUFA diet (20% of total calories) or a high-carb diet for one year led to comparable weight loss of around 8.8 pounds (4 kg) (6).
A larger study that combined the results of 24 other studies showed that high-MUFA diets are slightly more effective than high-carb diets for weight loss (7).
Therefore, high-MUFA diets can be an effective way to lose weight when replacing other calories, rather than adding extra calories to the diet.
Summary: High-MUFA diets can help with weight loss and may be more effective than low-fat, high-carb diets.
There is a big debate in nutrition about whether excessive saturated fats increase the risk of heart disease.
However, there is good evidence that increasing MUFAs in your diet can reduce risk factors for heart disease, especially if you’re replacing saturated fat.
Too much cholesterol in the blood is a risk factor for heart disease, as it can clog arteries and lead to heart attacks or stroke. Various studies have shown that a high intake of monounsaturated fats can reduce blood cholesterol and triglycerides (8, 9, 10).
For example, one study of 162 healthy people compared three months of a high-MUFA diet with a high-saturated fat diet to see the effects on blood cholesterol.
This study found that the diet high in saturated fat increased unhealthy LDL cholesterol by 4%, while the high-MUFA diet reduced LDL cholesterol by 5% (11).
High-MUFA diets can help lower blood pressure, too. A large study of 164 people with high blood pressure found that a high-MUFA diet lowered blood pressure and the risk of heart disease, compared to a high-carb diet (15).
However, it is important to note that the beneficial effects of high-MUFA diets are only seen when they replace saturated fat or carbs in the diet.
Furthermore, in each of these studies, the high-MUFA diets were part of calorie-controlled diets, meaning that adding extra calories to your diet through high-MUFA foods may not have the same benefits.
Summary: High-MUFA diets may help reduce blood cholesterol, blood pressure and other heart disease risk factors, particularly if they replace some saturated fats in the diet.
There is also some evidence that diets rich in MUFAs may help reduce the risk of certain cancers.
Prostate cancer, for example, is one of the most common types of cancer in men, especially older men.
Many studies have examined whether men who eat a good amount of MUFAs have reduced or increased rates of prostate cancer, but the evidence remains unclear.
Each of the studies examining the role of high-MUFA diets in prostate cancer has found different results. Some show a protective effect, some show no effect and others show a harmful effect (18, 19, 20).
One of these studies suggested that other components of high-MUFA foods may cause the protective effect rather than the MUFAs themselves. Therefore, it is unclear how MUFAs affect prostate cancer.
One large study of 642 women found that those with the highest amounts of oleic acid (a type of MUFA found in olive oil) in their fat tissue had the lowest rates of breast cancer (24).
However, this was only seen in women in Spain — where olive oil is widely consumed — and not in women from other countries. This suggests it may be another component of olive oil that has a protective effect.
Moreover, all of these studies were observational, meaning they can’t prove cause and effect. Thus, other components of diet and lifestyle may be contributing to this beneficial effect.
Summary: People with high MUFA intakes have lower rates of breast cancer. However, this may due to other components of MUFA-containing foods, rather than MUFAs themselves.
Insulin is a hormone that controls your blood sugar by moving it from the blood into your cells. The production of insulin is important for preventing high blood sugar and type 2 diabetes.
Studies have shown that high-MUFA diets can improve insulin sensitivity in both those with and without high blood sugar.
One study of 162 healthy people found that eating a high-MUFA diet for three months improved insulin sensitivity by 9% (28).
A similar, separate study of 472 people with metabolic syndrome found that those who ate a high-MUFA diet for 12 weeks had significantly reduced insulin resistance (29).
Summary: High-MUFA diets may be beneficial for improving insulin sensitivity and blood sugar control in those with and without high blood sugar.
Inflammation is a normal immune system process that helps your body fight infection.
But sometimes inflammation happens slowly over a long period of time, which can contribute to chronic diseases like obesity and heart disease.
Compared to other diets, such as high-saturated fat diets and Western diets, high-MUFA diets can reduce inflammation.
One study found that high-MUFA diets reduced inflammation in patients with metabolic syndrome, compared to high-saturated fat diets (33).
Other studies have shown that people who eat a Mediterranean diet high in MUFAs have significantly lower inflammatory chemicals in their blood, such as C-reactive protein (CRP) and interleukin-6 (IL-6) (34, 35, 36).
High-MUFA diets can also reduce the expression of inflammatory genes in fat tissue compared to high-saturated fat diets. This may be one of the ways that MUFAs are helpful for weight loss (37).
By reducing inflammation, high-MUFA diets may help to reduce the risk of chronic diseases.
Summary: High-MUFA diets may help to reduce inflammation, a process that can contribute to chronic disease.
The best sources of MUFAs are plant-based foods, including nuts, seeds and olive oil. They can be found in meat and animal-based foods, as well.
In fact, some evidence suggests that plant-based sources of MUFAs, particularly olive oil, are more desirable than animal-based sources (38).
This may be due to the additional beneficial components in olive oil.
Here is a list of foods high in MUFAs, along with the amount found in 3.5 ounces (100 grams) of the food:
- Olive oil: 73.1 grams
- Almonds: 33.6 grams
- Cashews: 27.3 grams
- Peanuts: 24.7 grams
- Pistachios: 24.2 grams
- Olives: 15 grams
- Pumpkin seeds: 13.1 grams
- Pork: 10.7 grams
- Avocados: 9.8 grams
- Sunflower seeds: 9.5 grams
- Eggs: 4 grams
Summary: MUFAs are found in animal- and plant-based foods. The best sources are olive oil, nuts and seeds.
Monounsaturated fats are healthy fats most commonly found in olive oil, nuts, seeds and some animal-based foods.
Diets high in monounsaturated fats can help with weight loss and may reduce risk factors for heart disease, as long as they don’t add extra calories to your diet.
Foods that contain MUFAs, especially olive oil, may also help reduce cancer risk, inflammation and insulin resistance.
Although it is also important to eat other types of fat, replacing unhealthy fats with MUFAs can provide a number of health benefits.