Which is healthier? A high-fat diet or a low-fat diet?
Conflicting reports make it difficult to tell. And media advice is equally confusing. Low- fat has been a dietary mantra for decades. But new diet books endorse everything from a low fat-high carb diet to a diet high in fats and low in carbs.
Then how about the different kinds of fat: Saturated, Poly-unsaturated, Mono- unsaturated, Fish Oils and Trans-Fat? Where do they all fit in?
To find the answers and to fit all the pieces together, I've drawn on the latest information from many of the nation's top research and medical centers. There's no doubt that fat is making a comeback on the nutritional scene. Meanwhile, new information on the link between dietary fat and arthritis, heart disease, cancer and other common diseases has made much of what we previously knew about fat obsolete.
For instance, it's now known that inflammation plays a key role in nearly all of the chronic diseases that afflict Americans. We've also learned that much of the fat we eat is converted into compounds called prostaglandins. And the fats from certain foods produce prostaglandins that promote inflammation and worsen our aches, pains and chronic diseases while fats from other foods produce prostaglandins that are anti-inflammatory and that may relieve our aches and pains and help us feel better.
And, Yes, we know exactly which foods contain fats that provoke inflammation and which foods contain fats that are anti-inflammatory. Obviously, the more we know about these exciting discoveries, the more we can control our health, our life and our destiny.
So let's begin by becoming familiar with the various kinds of dietary fats and the foods they are found in.
MAIN TYPES OF DIETARY FATS
Saturated Fat
This sinister fat is primarily found in meat, poultry skin and all dairy products but non-fat varieties, and in tropical oils like palm or coconut oil, cocoa butter or cream substitutes. For decades, Saturated Fat has been known as a proven artery clogger and a major cause of heart disease, claudication, hypertension and ischemic stroke.
Most health advisory agencies recommend limiting saturated fat to a maximum of 10% of dietary calories. But for a really heart-healthy diet, some experts suggest restricting saturated fat to only 7% of daily food calories. In reality, however, 13% of the average American's daily calorie intake is derived from saturated fat.
Foods loaded with saturated fat include ground beef and ground beef burgers, hard cheeses, ice cream and most full-fat dairy products. Even 1%- and 2%-fat milk contains a sizeable amount of saturated fat. While this fat has not been linked to iunflammation, our need for saturated fat is minimal. Thus a good general rule is that the less saturated fat we eat, the better.
Poly-Unsaturated Fatty Acids
These fats are found mainly in vegetable seeds and in oils pressed from them; and also in fish body oils. Poly-unsaturated fats are also known as Essential Fatty Acids or EFAs. While the body can make most of the fats it needs from sugar and starches we eat, humans are unable to make EFAs and must obtain them from food. EFAs exist in many plant foods but are most abundant in vegetable oils and they are precursors of tiny but powerful hormone-like compounds called prostaglandins. Some prostaglandins promote inflation while others are anti-inflammatory.
EFAs come in two distinct families, each with a different molecular structure.
OMEGA-3 EFAs FROM FISH OILS are the poly-unsaturated fatty acids found in the flesh of oily fish like sardines, salmon, anchovies, mackerel, herring, and bluefish. Fish oil is composed of two separate fatty acids:
EPA--Eicosapentaenoic acid, an Omega-3 fat needed to manufacture anti-inflammatory prostaglandins.
DHA--Docosahexaenoic acid, an Omega-3 fat essential for proper functioning of brain, nervous system and eyesight.
EPA and DHA are precursors of prostaglandins that have a powerful anti-inflammatory effect. They are identical to the EPA and DHA produced in Omega-3 Plant Foods (described below). But fish oils are a far richer source of EPA and DHA.
These highly desirable fatty acids are believed to inhibit tumor growth by crowding Omega-6 fatty acids (see below) out of cells. They also have a powerful anti-arrythmic effect. And by reducing inflammation in blood vessels, they prevent blood clots, and keep blood vessels relaxed and blood pressure lower.
For these reasons, most health advisory agencies recommend eating from 2-5 three ounce (90 gram) servings of oily fish each week, with 5 being preferable.
Most nutritionists recommend eating fish rather than fish oils (like cod liver oil) or taking fish oil supplements. Fish should not be fried or smoked. Canned sardines are one of the cheapest sources of Omega-3 fatty acids but should be packed in sardine, olive or canola oil, water or tomato sauce.
OMEGA-3 EFAs FROM PLANTS consist predominantly of alpha-linolenic fatty acid which is found in spinach and other dark green leafy vegetables, walnuts and other nuts, flaxseeds and flaxseed oil, in tofu and soy products, and also in canola oil.
In the body, alpha-linolenic fatty acid breaks down into
EPA or Eicosapentaenoic fatty acid, some of which is further converted into DHA or Docosahexaenoic fatty acid. Like the EPA and DHA in fish, these are precursors of prostaglandins that are primarily anti-inflammatory.
Under ideal conditions, our bodies can convert EPA and DHA from unprocessed plant foods into prostaglandins that inhibit inflammation. But in modern life, the process is hindered by too much sugar in the diet and by alcohol, aging or diabetes. The entire process is also neutralized by the large amounts of Omega-6 fatty acids we eat (see below) and by trans-fatty acid consumed in the Western diet. All of which means that oily fish are the best source of alpha-linolenic fatty acid.
Most Americans and Europeans need far more alpha-linolenic fatty acid than we currently consume. And we can all benefit by eating more of this healthful fat.
OMEGA-6 EFAs consist primarily of linoleic fatty acid and are abundant in vegetable oils such as safflower, sunflower, corn, cottonseed and soybean; they are also widely used in processed foods.
(Although strictly-speaking an Omega-9 mono-unsaturated fat, Canola Oil--made from the seeds of the Rapeseed plant--is being increasingly regarded as an Omega-6 fatty acid.)
In the body, linoleic acid is converted into several different compounds called Eicosanoids which become powerful prostaglandins that promote inflammation.
All of the Omega-6 cooking oils just mentioned can lower total cholesterol levels but once these oils are opened and exposed to air, they swiftly become rancid and release free radicals. Free radicals are rogue molecules that damage the DNA of cells, causing mutations that may eventually lead to cancer. Some studies have found that linoleic fatty acid promotes rapid cell division and that tumor cells thrive on it. Free radicals may also oxidize LDL (bad cholesterol) and damage arteries, leading to heart disease or hypertension.
Some linoleic acid is necessary for growth and fertility, and a deficiency can lead to hormonal disturbances or immunological abnormalities. But most of us eat far too much linoleic acid rather than too little, provoking inflammation in our arteries and organs that often leads to arthritis, heart disease, stroke, cancer and even diabetes.
OMEGA-9 Mono-Unsaturated Fats
These are known as neutral fats because they appear to lower LDL (bad cholesterol) without lowering HDL (good cholesterol), all without producing free radicals that may lead to cancer or artery blockage.
These very desirable fats are found in unprocessed plant foods and especially in nuts and avocadoes and in olive oil. Peanut butter is also an exceptionally good source provided it is also free of Trans-fat and sugar. Until recently, Canola Oil was classed as a mono-unsaturated fatty acid but in recent years, many researchers have come to group it with the less-desirable Omega-6 cooking oils.
Trans-Fatty Acid
This man-made fat is listed on food labels as hydrogenated or partially-hydrogenated vegetable oil. But the amount is not currently specified. Because manufacturers hide the actual amount of this proven artery clogger, trans-fat is often called "The Stealth Fat"--an unhealthful fat that has stolen its way into almost every type of processed food from stick margarine to snack foods, fast foods, fried foods, plus baked goods, vegetable shortening, candy bars, frozen dinners, boxed mixes. salad dressings, theater popcorn, potato chips and just about all commercial breads.
Trans-fat is a by-product of hydrogenation, a process used by food manufacturers to extend the shelf life of poly-unsaturated vegetable oils. That's because poly-unsaturated oils are unstable and turn rancid at room temperature on exposure to air.
To prevent this, manufacturers force hydrogen molecules into vegetable oils in a process called hydrogenation. This hardens the oils and gives them a rich, creamy texture. But hydrogenation transforms the chemical structure of unsaturated oils into trans-fatty acid.
Recent research has revealed that trans-fat acts like saturated fat, raising total cholesterol and bad cholesterol levels while also boosting triglycerides (unhealthful blood fat) levels. Though trans-fat totals only 2-3% of our food calories, it reduces artery flexibility and some researchers estimate it may raise the risk of heart disease by 50%.
Since food processors have persuaded the government to conceal the amount of trans-fatty acid in foods, one can only guess at how much we currently eat. But 2% of our total calorie intake should be max. And the good news is that trans-fats may soon be listed on food labels. Meanwhile, the less we eat of this high-risk fat the better.
Fats Are Seriously Out-Of-Balance In The Modern Western Diet
Two recent medical discoveries have forever changed the way we look at chronic disease. First, we learned that inflammation plays a key role in the onset of most disorders that afflict middle-aged and older Americans. Second, we learned that we ourselves can exert a great deal of control over inflammation in our bodies by adjusting the ratio of Omega-3 and Omega-6 fatty acids in our diet.
Nowadays, most westerners eat ten times as much inflammation-promoting Omega-6 fats as anti-inflammatory Omega-3s. Yet in primitive times, man ate roughly equal amounts. Early man's diet of wild game and leafy plants contained far less Omega-6 fatty acids than today's cattle fattened on feed lots, or our modern cultivated crops.
The technology for transforming seeds and grains into cooking oils rich in Omega-6 appeared only in the 1930s. Thus poly-unsaturated fats are fairly new to the human diet while hydrogenation of vegetable oils into trans-fatty acid is even more recent. Today, the western diet is seriously imbalanced: far too rich in Omega-6 cooking oils and far too poor in Omega-3 fats.
More On Reducing Inflammation Levels in Your Body
CRP , or C-Reactive Protein, is a marker in the bloodstream that indicates the extent of inflammation in the body. Recent studies confirm that inflammation may be as important as LDL (bad) cholesterol in causing heart disease or stroke. During tests, even when LDL cholesterol levels were normal, patients with the lowest CRP levels experienced slower onset of heart disease and fewer heart attacks and deaths.
While doctors all too often prescribe statin drugs to lower CPR levels, a healthy vegetarian diet and quitting smoking will also reduce inflammation. Better still is regular exercise. Men who exercise regularly have significantly lower CRP levels than sedentary men. Tests have not yet been done on women but similar results are anticipated.
Diets rich in plant sterols--found in avocadoes, soy protein. nuts, seeds and hi-fiber foods--also lower CRP levels.
Tests for CRP levels are simple and inexpensive but are usually reserved only for heart disease patients. If you do have a high CRP reading, daily aerobic exercise and a diet high in healthful vegetables and fruits is usually the best and cheapest way to reduce your inflammation level.
How To Balance The Fats In Your Diet
As a first step, a good target to aim for is to cut the Omega-6 fats in your diet to about 4 times as much as the Omega-3 fats that you eat. That is a ratio of 4:1. Later, you could aim for a 3:1 ratio or even a 2:1.
Counting calories or weighing foods is impractical for most people. It's far simpler to make a determined effort to eliminate all unfriendly fats from the diet and to replace them with friendly fats. In practice, this means cutting back on Omega-6 cooking oils plus saturated and trans fats. And replacing them with foods rich in Omega-3 fatty acids and Mono-unsaturated fat.
To start with, consider cutting out butter and all milk and dairy products but non-fat varieties; all foods containing tropical oils (palm and palm kernel oil, coconut oil and cream substitutes); all meat and meat products especially organ meats, hamburger, ground beef, bacon and sausage; and all foods containing trans-fatty acids including stick margarine and vegetable shortening. Then consider removing all skin from poultry and trimming all visible fat from any meat you do eat; consider eating only very low fat and non-fat cheeses; and eliminating all commercial baked goods, pies, cakes, cookies, and crackers plus candy and cheesecake.
If you do continue to eat meat, choose only very lean meats. Better, replace all meat and poultry with fatty fish. Avoid most Omega-6 cooking oils by strictly avoiding all FRIED FOODS plus all commercial baked goods and replacing Omega-6 cooking oils with Extra Virgin olive oil for all non-cooking use. Replace milk and dairy products (except nonfat varieties) with soy milk and soy products. And eat more--much more-- fruits, vegetables, nuts, seeds, whole grains and legumes.
To avoid putting on weight, whenever you add a healthy fat, drop a meal containing saturated or trans fats, or Omega-6 cooking oils. Just about all meat, poultry, dairy foods and eggs are poor in Omega-3 fatty acids.
Follow these guidelines and you will steadily replace foods that promote inflammation with foods that suppress and reduce inflammation in the body. Your arteries will become clearer and more youthful. And you will probably lose excess weight and feel better than you have in years.
Which Is Better: A High-Fat Or A Low-Fat Diet?
The answer depends on which fats we're talking about. When we're talking about unfriendly fats like Saturated, Poly-Unsaturated Omega-6 cooking oils, or Trans fat, most health advisory agencies recommend limiting dietary fat to a maximum of 25% of the total calories we consume. But where the majority of our fat intake consists of friendly fats like Omega-3 fatty acids and Mono-Unsaturated fats, our total fat intake could go as high as 35% without incurring any significant health risk.
A very low fat diet can cause a deficiency of fats needed to maintain our cell membranes and to boost the level of our HDL (good cholesterol). Without an adequate level of body fat, we cannot absorb such essential fat-soluble vitamins as A, D, E and K. And we may not be eating sufficient calories to fuel an active lifestyle.
At this point, I should explain that all fats are a mix of the four naturally-occurring fats, namely Saturated, Poly-unsaturated Omega 6 Linoleic acid, Poly-unsaturated Omega 3 Alpha Linolenic acid, and Mono-Unsaturated fat. Canola oil, for example, consists of Mono- unsatured fat (8.2 parts), Linoleic acid (2.8), Alpha Linolenic acid (1.3) and Saturated fat (1 part). Fats are named for their predominent type of fat. Thus Canola Oil is called a Mono-Unsaturated Fat (but nowadays is often grouped with Omega-6 fats because of its tendency to behave as Omego-6 fats do).
Regardless of types, all fats have 9 calories of energy per gram compared to only 4 calories per gram of protein or carbohydrate, the two other food categories. This makes friendly fats great sources of energy for bicycling or other endurance activities. Every gram of fat we eat gives us more than twice the energy of a gram of carbohydrates or protein.
In earlier times, when people lived more active lives, they burned up most of the surplus fat they ate. But in today's world, where so many of us spend our working hours at a desk or computer, surplus fat in our diet is transformed into surplus calories which are stored as fat in our cells.
Whether dietary fats are friendly or not, they can all turn into excess body fat and make us overweight. Various diet books have appeared in recent years claiming that diets high in protein and fat and low in carbohydrates cause loss of body weight. Most people do lose some weight on these diets for the simple reason that the diets are low in calories. And the protein component prevents a feeling of hunger.
These diets were designed strictly for weight-loss and no one knows how they affect our risk of heart disease, diabetes, cancer, arthritis or other chronic diseases. And how long can people tolerate the monotony of these diets? Moreover, these diets were designed for people who seldom eat fruits or vegetables and who rarely exercise. Anyone willing to exercise regularly can lose weight just as easily on a high-carbohydrate diet moderately low in fat and much more healthfully.
A couple of final cautions: Food processors have introduced low-fat versions of many processed high-fat foods. But in most cases, all they have done is to replace the calories from fat with just as many, or even more, calories from sugar and white flour. Low fat these foods may be but most are just as fattening as the high-fat versions they replaced. And these foods, like fat-free baked goods or potato chips, are invariably nutritionally-depleted.
Do you eat out often? In a restaurant, there's no way to tell whether the fats used in preparing your pizza or French fries were friendly or not, nor how much was used. The best strategy is to choose baked dishes or salads with a baked potato and to skip any fried foods.
We can't avoid unfriendly fats altogether. In fact, we need them in small quantities
Even canola or olive oils contain some Saturated fat and Omega-6 Linoleic acid fats. But by choosing friendly fats and avoiding the others whenever possible, our risk of developing arthritis or other chronic disease should be less than one-third that of the average American.
CAUTION: Though these reports are based on documented studies in professional journals or on advisories from leading university medical schools and research institutes, they are intended for information only and should not be regarded as medical advice or instruction. For diagnosis and treatment of specific symptoms and diseases, disorders or dysfunctions, consult your physician. If you smoke or are over 35 or have symptoms of--or are at risk for--any chronic or degenerative disease, you should check with your doctor before beginning to exercise or making any changes in lifestyle or diet. However, fitness organizations like the American College of Sports Medicine invariably believe that the risk of NOT exercising far exceeds any risk in beginning a gradually increasing program of daily exercise. Thus if you experience any pain or problem while exercising, or making any other lifestyle change, stop and see your doctor at once.