But what fats should you have in your diet?
Mainstream nutrition convinced us for decades that we needed to cut back on fat. Fat was the bad guy, they said, when it came to cardiovascular disease, obesity, diabetes, and a number of other modern ailments.
Recent studies, though, have shown that the low-fat diet hasn’t done what we thought it would do. In one 2006 study, a low-fat dietary pattern did not reduce risk of colorectal cancer. Another study that same year showed that reduced total fat intake did not significantly reduce the risk of cardiovascular disease (CVD), stroke, or coronary heart disease (CHD).
In a 2010 meta-analysis of 21 studies, researchers concluded, “there is no significant evidence for concluding that dietary saturated fat is associated with an increased risk of CHD or CVD.”
Another meta-analysis published in March 2014 involving over 600,000 participants concluded: “Current evidence does not clearly support cardiovascular guidelines that encourage high consumption of polyunsaturated fatty acids and low consumption of total saturated fats.”
Meanwhile, there is evidence that avoiding fat, particularly healthy fats, can be detrimental to your health. In 2011, for example, researchers reported that women with high blood pressure who ate 20 grams or less of saturated fat per day had double the risk of a hemorrhagic stroke as women eating moderate amounts (between 25 and 36 grams a day).
Eating a diet too low in fat can also interfere with vitamin and mineral absorption and increase risk of depression, cancer, heart disease (when the diet is too low in fat, HDL “good” cholesterol goes down), and even obesity, since low-fat alternative foods are often high in sugar and carbohydrates.
Researchers have cautioned, though, that these studies don’t mean everyone should go out and tank up on bacon, butter, and cheese. So what fats do we need in our diets?
Time to Feel Good About Healthy Fats
The truth is that we need fat for the body to function right. Here are just some of the benefits of fats:
- Support healthy membranes in the brain
- Help the body absorb nutrients
- Help create the membrane that surrounds every cell
- Help make hormones
- Provide for healthier skin
- Deliver energy
- Help prevent many diseases
- Help you feel full after a meal
- Can lower blood pressure
- Fight inflammation
- Make things taste good
We already know from recent studies that eating plant-based fats is good for us, and may help prevent heart disease. A 2010 study found that healthy polyunsaturated fat (PUFA)—in plant-based foods and oils—instead of “harmful” saturated fat (mainly from red meat and full-fat dairy), reduced risk of coronary heart disease.
Eating so-called “good” fats has also shown in some studies to lower LDL “bad” cholesterol and improve levels of HDL “good” cholesterol. It may also help prevent insulin resistance, a precursor to diabetes.
How to Tell if You’re Eating Too Little Fat
If you’re not getting enough fat in your diet, you may develop symptoms including the following:
- Weight gain: Hard to believe? The problem is that often when people shun fat, they eat too much sugar and too many carbohydrates. Fat helps us feel full. Without it, we may experience more cravings, causing us to eat more.
- Blood sugar ups and downs: Fats help keep your blood sugar levels stable, as they tend to take longer to digest. Without enough, you may experience spikes and dips.
- Brain fog/mental fatigue: Can’t remember things? Finding it hard to focus? Always mentally tired? Could be you’re not getting enough fats. They feed the brain and improve brain function.
- Dry, dull skin: Fats help support healthy skin and hair. They support oil-producing glands, which help keep skin and hair hydrated.
- Depression or the blues: Healthy fats support good mood neurotransmitters in the brain. Studies have found that low intake of essential fatty acids can increase risk of depression.
- Cold chills: Fats help regulate body temperature. If you’re not getting enough, you may always feel cold.
- Abnormal menstrual schedule: If you have too little fat in your diet, you could suffer hormonal imbalances, which could disrupt your monthly schedule.
Two Main Types of Fat—and What You Need
Experts recommend we make sure about 20-35 percent of our daily calories come from fat. (Children need more—up to 40 percent of daily calories.) So if we think of an average of 2,400 calories a day, that would be about 80 calories. Not much.
Still, with all the focus on low-fat diets, some of us may not be getting enough—or not getting the right kinds. Here’s a simple breakdown of the two main types of fats:
- Unsaturated fat: This type of fat is the most common. Sources include nuts, vegetable oils, fish, olive oil, and flaxseed. These are considered the “healthy fats” as they contain fewer calories than other fats, they help reduce risk of heart disease, and they may also reduce risk of type 2 diabetes. Both polyunsaturated and monounsaturated fats are in this category. Omega-3 and omega-6 fatty acids are polyunsaturated fats—both contribute to health, though in our modern diet we consume too many omega-6s and not enough omega-3s. Good sources of omega-3s include oily fish, eggs, lean meats, flaxseed, walnuts, and soybeans. Sources of omega-6s include sunflower and sesame seed oils, sunflower seeds, pecans and Brazil nuts.
- Saturated fat: Saturated fats are often solid at room temperature. They’re typically found in animal products. Sources include meat, eggs, butter, cheese, whole milk, cream, avocadoes, and some oils like coconut and palm kernel. Moderate amounts can help increase HDL “good” cholesterol and help you feel full.
Though research is ever-evolving, modern wisdom suggests the following:
- Eat both types: The body needs both types of fats on a regular basis for optimal health.
- Avoid bad sources: When choosing saturated fats, avoid those with other things that may hurt your health. Go for grass-fed beef, for example, rather than conventionally grown (with antibiotics and hormones). Real butter, as opposed to synthetic margarines with potentially harmful ingredients.
- Stay away from trans fats: These have been found to definitely increase the risk of heart disease and type 2 diabetes. They’re present in typical donuts, cookies, cakes, muffins, potpies, frozen pizzas, and the like. Look for those with “0 trans fat” on the label, and then check the ingredient list. Avoid any with “partially hydrogenated oils.”
- Consume more healthy fats, like the unsaturated types listed above.
- Don’t be afraid of fat. We’ve been taught to avoid fat at all costs. It’s time to rewire our brains. Some fat is good for us, and important for overall health. Eggs, dark chocolate, some meats, coconut oil, butter, cheese, and dairy are okay in moderate amounts.
What do you think of the latest research on fat? Have you changed your diet?
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Shirley A. Beresford, et al., “Low-Fat Dietary Pattern and Risk of Colorectal Cancer: The Women’s Health Initiative Randomized Controlled Dietary Modification Trial,” JAMA, Febraury 8, 2006, 295(6):643-654, http://jama.jamanetwork.com/article.aspx?articleid=202340.
Howard BV, et al., “Low-fat dietary pattern and risk of cardiovascular disease: the Women’s Health Initiative Randomized Controlled Dietary Modification Trial,” JAMA, February 8, 2006; 295(6):655-66, http://www.ncbi.nlm.nih.gov/pubmed/16467234.
Patty W. Siri-Tarino, et al., “Meta-analysis of prospective cohort studies evaluating the association of saturated fat with cardiovascular disease,” Am J Clin Nutr, January 2010, http://ajcn.nutrition.org/content/early/2010/01/13/ajcn.2009.27725.abstract.
Rajiv Chowdhury, et al., “Association of Dietary, Circulating, and Supplement Fatty Acids with Coronary Risk: A Systematic Review and Meta-analysis,” Ann Intern Med., 2014; 160(6):398-406, http://annals.org/article.aspx?articleid=1846638.
American Heart Association, “Risk of rare stroke highest in women with lowest saturated fat intake, study finds,” Press Release, February 11, 2001, http://www.eurekalert.org/pub_releases/2001-02/AHA-Rors-1102101.php.
Mozaffarian D, et al., “Effects of coronary heart disease of increasing polyunsaturated fat in place of saturated fat: a systematic review and meta-analysis of randomized controlled trials,” PLoS Med, March 23, 2010; 7(3):e1000252, http://www.ncbi.nlm.nih.gov/pubmed/20351774.