Friendly Fats -- And Fiendish Ones

(CBS) Fats get a bad rap. 

Many people think they're all unhealthy when, in reality, many have lots of nutritional value, as registered Dietician Cynthia Sass pointed out on "The Early Show" Thursday. 

And that matters a lot, since about a-third of our calories each day should come from fat. 

So, which ones are the best? 

Sass, co-author of "The Ultimate Diet Log," (read an excerpt) served up the facts on fats: 

It may seem counterintuitive, but eating more fat is one of the best strategies for slimming down and staying healthy. 

Fat is one of the most important nutrients in your diet. It's a structural part of every cell membrane in your body, which means you can't heal a cell or construct a new one without this key building block. Fats also are a component of skin and hair, and certain types of fats are essential for controlling blood clotting, keeping your brain healthy, and fighting inflammation in your body. Without fat, you wouldn't be able to absorb certain antioxidants and the fat-soluble vitamins -- A, D, E and K -- that "hitch a ride" with fat to get transported from your digestive system into your blood. In my private practice, I have fat-phobic clients who cut their fat intakes too low and, as a result, experience fatigue, dry skin, dull hair and irregular periods -- these are corrected once they start eating enough "good" fat. 

All fats have the same number of calories (9 per gram compared to 4 per gram in protein and carbohydrate), but choosing low-fat foods isn't the best recommendation. 

Some of the healthiest foods on the planet are high in fat -- such as extra virgin olive oil, avocados and almonds. 

The key is to eat smaller portions of healthy, high fat foods. For instance, low-fat peanut butter typically has 10 fewer calories per serving (sometimes the same number of calories), but it has more sugar. When they remove fat, they have to fill its space. Choose all-natural, full-fat peanut butter and other unprocessed, whole foods that contain plant-based fats. 

But not all fats are created equal! Some are good and some are bad. 

There are four main types of fat in food: 

Saturated
Trans or partially hydrogenated
Monounsaturated (aka MUFA)
Polyunsaturated (aka PUFA) 

SATURATED FATS 

Saturated fats, from animal-based foods like whole-milk dairy products and fatty cuts of meat, are known as one of the bad guys. They've been linked to upping the risk of heart disease by clogging up arteries and boosting levels of "bad" HDL cholesterol. A recent study also found that animal-based saturated fats tend to override the body's satiety mechanism, the "I'm full" signals. 

But there are a few exceptions - fortunately, two of the most delicious! Recent studies have confirmed that saturated fats from dark chocolate and coconut are healthful. Coconut oil has been show to increase "good" HDL cholesterol levels, boost calorie and fat=burning, and help reduce dangerous belly fat. And a relatively large percentage of the saturated fat in cocoa gets converted to a heart-healthy monounsaturated fat that lowers LDL and raises HDL. And because both cocoa and coconut are plants, they're also rich in antioxidants. 

TRANS-FATS 

There's no good news here! Man-made trans-fats, found in foods like crackers, cookies, baked goods and fast food, is crafted from partially hydrogenated oil, which means liquid oil that had hydrogen added to it to make it solid. It's been shown to boost weight gain and belly fat even when the exact same number of calories are consumed and the percentage of total fat is identical. Trans-fats have also been linked to an increased risk of infertility. One study found that infertility risk jumped by a whopping 73 percent with each 2 percent increase in trans-fat. 

Trans-Fat Loophole 

Unfortunately, food products can claim to provide zero grams of trans fat if the food contains less than 0.5 grams per serving (to identify this "hidden" trans fat, check the ingredient list for the words partially hydrogenated). And, a product can also be labeled trans-free if it's made with FULLY hydrogenated instead of partially hydrogenated oil. Technically, fully-hydrogenated oils are trans-free, but they're not risk-free. A Brandeis University study found that eating products made with fully hydrogenated oil, a trans-free alternative to partially hydrogenated oil) may lower HDL, the good cholesterol and cause a significant rise in blood sugar (about 20 percent). At least, that's what the 30 healthy subjects the researchers studied experienced - in just four weeks' time. The best way to avoid both partially- and fully-hydrogenated oils is to eat as many unprocessed or minimally processed foods as possible. For example, choosing liquid oil as opposed to margarine, and nuts and fruit as a snack instead of something that comes in a bag or box. 

MONOUNSATURATED (aka MUFA) 

MUFAs are found in many oils, like extra virgin olive oil and sesame oil, avocados, nuts, seeds and natural nut butters. They've been shown to help to regulate appetite, keep your weight under control and reduce the risk of many chronic diseases, including heart disease and cancer, and help preserve cognitive function and improve longevity. MUFAs go to work in the body to lower the "bad" LDL cholesterol, increase your "good" HDL cholesterol, and keep your arteries soft and flexible, reducing the risk of heart attack and stroke. They've also been shown to help reduce the accumulation of dangerous belly fat. 

POLYUNSATURATED FATS (aka PUFAs) 

PUFAs are a bit of a mixed bag. The PUFA champions are omega-3 fatty acids, particularly DHA and EPA. These are found in abundance in fish like salmon and sardines. Non-fish eaters can obtain DHA from algae and EPA from other plant sources. Corn oil is also in the PUFA category, a type known as omega-6. We need omega-6 fatty acids, but most of us aren't getting the right balance. Too much omega-6 and not enough omega-3 has been linked to inflammation, a known trigger of aging and disease. Getting enough omega-3 fatty acids and improving the balance has been shown to reduce the risk of dozens of illnesses from heart disease, Alzheimer's and dementia to asthma and allergies, diabetes, arthritis and depression. 

BOTTOM LINE 

According to the National Institutes of Health, about 35 percent of the calories you eat per day should come from fat, as long as most are from healthy, plant-based foods. That's about 60 grams a day for most of us, or roughly 15-20 per meal. 

Eat more "good" fat by making a few simple swaps: 

Spread ripe avocado or natural peanut or almond butter on toast in place of butter 

Sauté veggies in oil instead of butter 

Use an oil based vinaigrette on salad instead of a creamy or cheesy dressing 

Replace some or all of the ground beef in a recipe with chopped mushrooms sautéed in extra virgin olive oil 

The best strategy is to include a little at each meal to prevent going overboard -- sprinkle a few tablespoons of nuts into your oatmeal, add a quarter of avocado to your salad or sandwich at lunch, and whip up a stir fry for dinner using one tablespoon of oil.  

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