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Choosing Healthy Fats

Good Fats, Bad Fats, and the Power of Omega-3s

Salmon with lemon

For years, nutritionists and doctors have preached that a low-fat diet is the key to losing weight and preventing health problems. However, not all fat is the same. While bad fats can wreck your diet and increase your risk of certain diseases, good fats protect your brain and heart. In fact, healthy fats—such as omega-3s—are vital to your physical and emotional health. Understanding how to include more healthy fat in your diet can help improve your mood, boost your well-being, and even trim your waistline.

What you can do

  1. Learn which fats are essential to your mental and physical health
  2. Find out how to add more unsaturated fats to your diet
  3. Shop for cold-pressed oils instead of processed oils
  4. Understand the benefits of omega-3s—and the best sources
  5. Discover what makes trans-fat so damaging
  6. Make sense of the debate about saturated fat

Why are we so afraid of fat?

A walk down any grocery store aisle will confirm our obsession with low- and no-fat foods. We’re bombarded with supposedly guilt-free options: fat-free milk, cheese, and yoghurt, low-fat cookies, cakes, and frozen dinners. But while our low-fat options have exploded, so have obesity rates. Clearly, all these low-fat foods haven’t delivered on their trim, healthy promises.

The reason for that is simple: not all fat is bad. In fact, your body needs fat. Healthy or “good” fats are essential to help manage your moods, stay on top of your mental game, fight fatigue, and even control your weight. Since the human brain is nearly 60 percent fat, healthy fats are also vital for proper brain development and function. The answer isn’t cutting out the fat—it’s learning to make healthy choices and to replace bad fats with good ones that promote health and well-being.

Myths and facts about dietary fat

Myth: All fats are equal—and equally bad for you.

Fact: Some fats raise your cholesterol and increase your risk for heart disease, while others lower cholesterol, reduce your risk of heart disease, and provide other health benefits.

Myth: Fat-free means healthy.

Fact: A “fat-free” label doesn’t mean you can eat all you want without consequences to your waistline. Many fat-free foods are high in sugar, refined carbohydrates, and calories.

Myth: Eating a low-fat diet is the key to weight loss.

Fact: The obesity rates for Americans have doubled in the last 20 years, coinciding with the low-fat revolution. Since fats are filling, they can help curb overeating.

Good fats vs. bad fats

There are four major types of dietary fat found in food from plants and animals:

  1. Monounsaturated fats (good)
  2. Polyunsaturated fats, including omega-3s (good)
  3. Trans fats (bad)
  4. Saturated fats (debated)

Of course, labeling certain fats “good” and others “bad” can be a little simplistic. After all, it takes more than just the fat content of food to determine whether it’s healthy or unhealthy. How it’s raised or grown, how it’s prepared, and any additives used can make a huge difference to whether a food is healthy or unhealthy. While fish can be packed with healthy omega-3 fats, for example, deep frying it in refined vegetable oil can add unhealthy trans fat, making it potentially harmful. And while monounsaturated and polyunsaturated fats from whole foods are universally considered good fats, those from industrially manufactured oils are often considered dangerous.

The debate over saturated fat

There’s an ongoing debate in the nutrition world about the merits and dangers of saturated fat and no clear consensus on exactly where it falls on the spectrum of good fats to bad. While some nutrition experts argue that it contributes to weight control and overall health, many prominent health organizations maintain that eating saturated fat increases the risk of heart disease and stroke.

Tips for adding more healthy fats to your diet

Whole food sources of unsaturated fats can improve blood cholesterol levels, lower your risk of heart disease, and benefit insulin levels and blood sugar. Omega-3 fats are particularly beneficial for your brain and mood. The best sources are fish, nuts, and seeds.

Good Fats
Monounsaturated fat
  • Avocados
  • Olives
  • Nuts (almonds, peanuts, macadamia nuts, hazelnuts, pecans, cashews)
  • Natural peanut butter (containing just peanuts and salt)
Polyunsaturated fat
  • Walnuts
  • Soymilk and tofu
  • Sunflower, sesame, flax, and pumpkin seeds
  • Fatty fish (salmon, tuna, mackerel, herring, trout, sardines)

Beware of certain unsaturated oils

There are basically two types of unsaturated vegetable oils:

  1. Traditional, cold-pressed oils such as extra virgin olive oil, peanut oil, and sesame oil that are rich in monounsaturated fats and made without the use of chemicals or heat.
  2. Modern processed oils such as soybean oil, sunflower oil, corn oil, canola oil, cottonseed oil, and safflower oil which are industrially manufactured—usually from genetically modified crops in the U.S.—using heat and toxic solvents.

Some nutritionists feel that these manufactured vegetable oils shouldn’t be included as “good” fats because the damaging industrial processing can transform the fatty acids into dangerous trans fat.

When good fats go bad

A good fat can become bad if heat, light, or oxygen damages it.

  • Polyunsaturated oils must be refrigerated.
  • Cooking at high heat with some unsaturated oils can damage the fat.
  • Discard oils, seeds, or nuts if they smell or taste bitter.

Olive oil fraud

A lot of imported "olive oil" is actually a combination of olive oil and cheaper, refined oil. To protect yourself:

  • Opt for olive oil with the California Olive Oil Council (COOC) logo on a bottle.
  • For olive oils from France: look for the “AOC” logo, from Italy: the “DOP” logo, and from Spain: the “DO” seal.

Source: Berkeley Wellness

Eat omega-3s often

Omega-3 fatty acids are a type of polyunsaturated fat and are proving to be especially beneficial to health. Research has shown that they can:

  1. Prevent and reduce symptoms of depression, ADHD, and bipolar disorder
  2. Protect against memory loss and dementia
  3. Reduce the risk of heart disease, stroke, and cancer
  4. Ease arthritis, joint pain, and inflammatory skin conditions
  5. Support a healthy pregnancy
  6. Help you battle fatigue, sharpen your memory, and balance your mood

The different types of omega-3 fatty acids:

EPA and DHA found in fish and algae have the most health benefits.

ALA comes from plants and is a less potent form of omega-3 than EPA and DHA, although the body does convert ALA to EPA and DHA at low rates.

The best sources of omega-3s

While most of us obtain plenty of omega-6 fats in our diets, we need to increase our intake of omega-3s to maintain a healthy ratio.

Fish: the best sources of omega-3s
  • Salmon (especially wild-caught king and sockeye)
  • Herring
  • Mackerel
  • Anchovies
  • Oysters
  • Sardines
  • Pole and line-caught tuna
  • Lake trout
Vegetarian sources of omega-3s
  • Algae such as seaweed (high in EPA and DHA)
  • Brussels sprouts
  • Walnuts
  • Flaxseed
  • Fish oil or algae supplements
  • Kale
  • Spinach
  • Parsley

Mercury in fish

Despite the health benefits, nearly all seafood contains traces of pollutants, including the toxic metal mercury. The concentration of pollutants increases in larger fish, so avoid eating shark, swordfish, tilefish, and king mackerel.

Most adults can safely eat 12 ounces (two 6-ounce servings) of cooked seafood a week. For women who are pregnant, nursing mothers, and children under 12, choose fish lower in mercury, such as shrimp, canned light tuna, salmon, pollock, or catfish. Eat no more than 6 ounces (one average meal) of albacore tuna per week.

Fish fraud

In 2013 testing, one third of fish in the U.S. was found to be mislabeled. Similar fraud has been exposed in almost every other part of the world. Fraudulent labels are most commonly put on fish sold as cod, grouper, red snapper, and wild salmon. To protect yourself:

  • Find a reputable fishmonger you can trust.
  • Buy whole fish whenever possible.

Source: Berkeley Wellness

If you don’t eat fish, consider taking an omega-3 supplement

While omega-3s are best obtained through food, there are many omega-3 and fish oil supplements available.

Avoid products that don’t list the source of their omega-3s. The package should list the source of omega-3 fatty acids as fish oil, krill oil, or algae.

Look for the total amount of EPA and DHA on the label. The bottle may say 1,000 milligrams of fish oil, but it’s the amount of omega-3 that matters.

Choose supplements that are mercury-free, pharmaceutical grade, and molecularly distilled. Supplements derived from molecularly distilled fish oils tend to be naturally high in EPA and DHA and low in contaminants. Choose a supplement that has been independently tested to be free of toxins.

How much omega-3 do I need?

For most people, two 6 oz. servings of fatty fish a week, as well as regular servings of ALA-rich vegetables provides a healthy amount. For fish oil supplements, look for 700-1,000 mg of EPA and 200-500 mg of DHA daily. Many algae supplements have a lower recommended dose due to the higher concentration of omega-3s.

Eliminate trans fat from your diet

Small amounts of naturally occurring trans fats can be found in meat and dairy products but it’s artificial trans fats that are considered dangerous. These dangerous trans fats are normal fat molecules that have been deformed during a process called hydrogenation, where liquid vegetable oil is heated and combined with hydrogen gas. Partially hydrogenating vegetable oils makes them more stable and less likely to spoil.

No amount of artificial trans fats is healthy. Trans fats raise your LDL ("bad") cholesterol and lower your HDL ("good") cholesterol and increase your risk of heart disease, stroke, and diabetes.

Look for hidden trans fat in your food

The USDA recommends limiting trans fat to no more than 2 grams per day; many other authorities recommend eliminating it altogether. In the U.S., if a food has less than 0.5 grams of trans fat in a serving, food companies can label a product as having 0 grams. You may think that what you’re eating is safe but all those small amounts can quickly add up to dangerous levels, especially if you consume more than the recommended serving.

Check the food’s ingredients. If it lists “partially hydrogenated” oil then the food contains trans fat.

Reduce fried food. While there’s a movement to ban trans fat in the U.S., that won’t make your French fries any healthier if they’re cooked in vegetable oils that oxidize when heated. It’s safer to cut down on fried foods altogether.

Avoid fast food. Most states have no labeling regulations for fast food, and it can even be advertised as cholesterol-free when cooked in vegetable oil.

When eating out, talk to your server. Ask if your food can be prepared using olive oil instead of partially hydrogenated oil.

Common sources of bad trans fat

  • Commercially baked goods (cookies, crackers, cakes, muffins, pie crusts, pizza dough, breads like hamburger buns)
  • Packaged snack foods (crackers, microwave popcorn, chips, candy)
  • Solid fats (stick margarine, vegetable shortening)
  • Fried foods (French fries, fried chicken, chicken nuggets, breaded fish, hard taco shells)
  • Pre-mixed products (cake mix, pancake, chocolate milk)
  • Anything with "partially hydrogenated" oil listed in the ingredients

Be smart about saturated fat

Prominent organizations such as the American Heart Association and the American Diabetes Association maintain that eating saturated fat from any source increases your risk of heart disease and stroke. Other nutrition experts cite studies that suggest that people who eat saturated fat do not experience more cardiovascular disease than those who eat less, and that eating whole-milk dairy products is linked to less body fat and lower levels of obesity. They believe that eating full-fat dairy makes you feel fuller for longer, thus helping you eat less overall. And that adding a little tasty butter to a plate of vegetables, for example, can make it easier to eat healthy food and thus improve the overall quality of your diet.

However, none of these findings have compelled health organizations to change their recommendations. To be safe, always talk to your doctor before changing your diet or eating saturated fat in anything but moderation—especially if you have other risk factors for cardiovascular disease.

Making healthier saturated fat choices

  • Avoid all saturated fat from processed meats, packaged meals, takeout food, and snack foods such as corn or potato chips.
  • Don’t replace saturated fat with refined carbs or sugary snacks. If in doubt, opt for good sources of monounsaturated and polyunsaturated fats.
  • Don’t eat too much red meat (beef, pork, or lamb) but vary your diet with free range chicken, eggs, fish, and vegetarian sources of protein.
  • When you do eat red meat, look for "organic" and “grass-fed”.
  • Roast, grill, or slow cook poultry, fish, and meat instead of frying.
  • If you opt for full-fat dairy, enjoy it in moderation only, and choose organic or raw milk, cheese, butter, and yoghurt whenever possible.

Focus on fat from real food, not processed food

There are many opinions and few absolutes in the nutrition world. For most of us, it’s our overall dietary pattern that is more important than specific foods. What we do know for sure is that the typical Western diet—filled with fried, processed food, packaged meals, and sugary snacks—is leading to higher rates of obesity and illness. Eating less processed food and more “real,” natural food—fresh from the ground, the ocean, or small, local farms—is a sound place to start for all your food choices, including healthy fats.

Related HelpGuide articles

Resources and references

Types of fats: Good fats, bad fats

Healthy Fats – Explains the different types of fats and how much of them should be included in a healthy diet. (University of Michigan)

Figuring Out Dietary Fats – Outlines the importance of eating the right fats, rather than no fats. (Berkeley Wellness)

Trans Fat is Double Trouble for Your Heart Health – How trans fat lowers good and raises bad cholesterol. (Mayo Clinic)

Canola Oil Myths and Truths - A look a the health benefits and dangers of using canola oil. (Berkeley Wellness)

The debate about saturated fat

Saturated Fats – Outlines the long-held view that saturated fats raise cholesterol and increase the risk of heart disease and stroke. (American Heart Association)

Fats – Differentiates between healthy fats and unhealthy fats, including saturated fat, which should be limited for people with diabetes to prevent heart disease and stroke. (American Diabetes Association)

Dietary Guidelines for Americans – Summary of dietary guidelines, including recommended saturated fat limits. (USDA)

The Full-Fat Paradox – New research that concludes the consumption of whole-fat dairy is linked to reduced body fat. (NPR)

The End of the Debate? Fat Chance – Discusses the debate about saturated fats. (Berkeley Wellness)

Don't Fear the Fat – Experts question the existing saturated fat guidelines. (NPR)

Red meat and processed meat

More Reason to Avoid Processed Meat – The link between processed meat and increased risk of heart failure. (Berkeley Wellness)

World Health Organization Says Processed Meat Causes Cancer – Details the link between processed meat and certain types of cancer. (American Cancer Society)

Omega-3 fatty acids

Omega-3 Fatty Acids – Simple charts listing omega-3 fatty acid content of selected foods. (Tufts University)

Omega-3 fatty acids – Comprehensive article on omega-3 fatty acids and the role they may play in preventing several diseases and conditions. (University of Maryland Medical Center)

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Authors: Lawrence Robinson and Jeanne Segal Ph.D. Last updated: March 2017.