Fats: The good, the bad and the ugly

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— If Americans are confused about fats and their role in making us fat, it's little wonder. Many who followed the low-fat mantra of the 1990s were rewarded with ballooning waistlines as the national girth continued to expand.

The fat problem is complex. Fat is not a single entity, rather a smorgasbord of options and others that are just plain bad.

Our bodies need essential fatty acids found in fats to function. Fatty acids are required to absorb the fat-soluble vitamins A, D, E and K. Dietary fat, an important source of energy, is also needed to produce certain hormone-like compounds that govern weight. The body doesn't make its own fats so the key is not to avoid fats, but to use beneficial fats in moderate amounts.

Fats fall into two broad categories: saturated and unsaturated. Saturated fats are solid or semi-solid at room temperature and are generally of animal origin. They include butter, lard, red meat, dairy products and palm oil. Most of us know they're the fats we should be limiting in our diet.

Those with diets high in animal fats tend to have higher rates of atherosclerosis, heart disease, type 2 diabetes and certain cancers.

Unsaturated fats make up the other main category. In general, unsaturated fats are healthy fats when eaten in moderation. Of these, there are two main types, monosaturated and polyunsaturated. A healthy diet should contain some of each.

Monounsaturates are found in olive oil, canola oil, avocados and nuts. They help lower LDL (the bad cholesterol) and increase levels of HDL (the good cholesterol).

Polyunsaturates include both omega-3 and omega-6 fatty acids. Omega-6s are found in safflower, corn and soybean oil. They're the polyunsaturates we tend to eat most of.

Omega-3 fatty acids are a specialized type of unsaturated fat. They promote heart health and fight inflammation in the body plus they help the central nervous system and eyes stay healthy. Omega-3s are found in fatty fish like salmon as well as in flaxseed oil and nuts, especially walnuts.

Experts now believe that a healthy diet should strive to get at least 90 percent of fats consumed each day from a combination of unsaturated fats. Most Americans eat far fewer omega-3 fats than omega-6 and, according to health experts, they should make an effort to get more omega-3s.

Trans fats: The

new bad guy

Recent decades have seen the addition of a new and harmful player on the fat scene: trans fat. Developed by the food industry to improve the taste, texture and shelf life of packaged foods, trans fat have oozed into every corner of modern life.

They are polyunsaturated fats that have been converted into trans monosaturated fats.

Although natural monosaturated fats such as olive oil are good for you, trans fats are bad for you. They raise cholesterol levels, deposit plaque in arteries and damage blood vessels.

Trans fats are found in literally thousands of grocery store products and fast food items including cookies, crackers, margarines, cakes, granola bars, French fries, chips, salad dressings, candy, cereals and microwave or movie popcorn.

One problem for consumers was that food labels didn't list trans fat, making them more difficult to spot. That changed in January when food labels were required to list trans fat.

Fats and weight

control

All fats have nine calories per gram, making fat an energy-dense food. We all know that eating too much fat will make us gain weight. But eating too little fat is not necessarily the answer. Scientists believe the fats can actually help with weight loss.

Fats take longer to digest than either protein or carbohydrates, making us feel fuller for longer. Scientists are still working to understand the complex interactions between gut and brain, but they have identified a number of hormones, including leptin, that help regulate the energy balance in the body.

When it's functioning as it's intended, the body's energy equation works with amazing precision. A healthy male who maintains his weight at 175 pounds consumes an estimated one million calories per year and burns the same number.

To maintain this balance, the body's heat regulating system has to power up and down to adjust for normal fluctuations in calorie intake and activity levels. Leptin is the hormone that helps maintain this balance.

But, too much fat and high fructose sweeteners in the diet interferes with the regulation of leptin. And, as body fat increases, the brain becomes less sensitive to the effects of leptin, making weight loss increasingly difficult for the overweight.

As well as keeping weight under control, eating moderate amounts of fats and choosing the right kind of fats can protect us from a host of diseases.

Saturated fats are linked to hypertension and to secondary problems including retinal damage, vision loss and transient ischemic attacks, precursors of strokes.

A number of studies also show that a diet high in saturated fat significantly raises the risk of Alzheimer's disease. A high-fat diet is also believed to be responsible for the much higher rate of colon cancer in the United States, compared with Japan, a nation that eats a diet much lower in saturated fats.

According to a study published in the International Journal of Epidemiology, if Americans cut their intake of saturated fat from 15 percent to 10 percent of total calories, there would be a 25 percent decrease in mortality rate.

Changing eating habits is a gradual process, but you can make major improvements in your diet by cutting back on saturated and trans fats and substituting moderate amounts of unsaturated fats, emphasizing sources rich in omega-3s.

Start by substituting fish for meat a couple of nights a week, avoiding fried foods and cutting back on pre-packaged items. Read food labels, looking out for hydrogenated and partially hydrogenated oils, and select a healthy margarine to use as a spread. Many of the soft tub and liquid margarines are trans fat free. Use a little olive or canola oil when making salad dressing or for cooking. Sprinkle nuts on salads or cereal when substituting a small handful of peanuts for a handful of chips when you want a quick snack. Instead of cookies for dessert, try a piece of fresh fruit or fruit salad.

Increasingly, it's becoming apparent that the key to a healthy diet is being able to distinguish the good fats that are our friends from the bad fats that clog arteries and promote obesity.

When it comes to fat, recognizing the enemy is half the battle.

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