It is important to consider that in general, diet is difficult to study. First, information is often collected retrospectively. It may also be hard to discern whether specific dietary patterns led to the disease or whether the onset of disease symptoms led to specific dietary patterns.

A balanced diet includes wholesome foods in proper propotions and portions. One common way of depicting food proportions is by pictorial pyramids. There are many dietary food pyramids with conflicting data and advise. It's no wonder people are confused.

The pyramid that receives the most attention, is of course, the one our government promotes. More than a decade ago, the U.S. Department of Agriculture (USDA) created an enduring icon - the Food Guide Pyramid. This simple illustration conveyed what the USDA said were the elements of a healthy diet. Tragically, the information embodied in this pyramid didn't point the way to healthy eating. Why not? Its design was based on some unreliable evidence, and it barely changed over the years to reflect major advances in our understanding of the connection between diet and health. With much hype, the USDA recently jettisoned the old Food Guide Pyramid and replaced it with "MyPyramid," (basically the old pyramid turned on its side).

USDA's pyramid somewhat resembles the "Okinawan" or Asian Pacific diet, except that the latter stresses omega-3 fatty fish as a separate and major dietary component, and vegetable oils are stressed over dairy.

OKINAWAN / ASIAN-PACIFIC FOOD PYRAMID

As an alternative to the USDA's flawed pyramid, faculty members in the Harvard School of Public Health built the Harvard Med School Healthy Eating Food Pyramid. Their pyramid is actually based on the "Mediterranean diet" which was derived from the eating habits of the inhabitants of Crete and Southern Italy in the 1960s. The study was presented in 1993 by Walter Willett of the Harvard School of Public Health at the International Conference on the Mediterranean Diet held in Cambridge Massachusetts. Note that "good" plant oils are one of the primary components, in direct opposition to the current USDA pyramid which stresses processed grains.

Their research concludes that not all fat is created equal - monounsaturated fat doesn't raise blood cholesterol levels the way saturated fat does. However, monounsaturated fatty acids (like saturated fats) promote insulin resistance, whereas polyunsaturated fatty acids are protective against insulin resistance. This particular diet has enjoyed a decade of increasing acceptance.

HARVARD MEDICAL SCHOOL FOOD PYRAMID

Another "alternative" diet is promoted by Dr. Udo Erasmus. Like Atkins, Erasmus rails against carbohydrates as the LEAST important food. "Carbs speed fat production and slow down fat burning. I use a slogan for this situation: 'When you eat carbs, either you burn them or you will wear them - as fat.'" His theory goes: Athletes can eat much more carbohydrate food than sedentary people can because they burn it up during intense physical activity. The more active a person, the bigger their muscles, and the more they exercise, the more carbohydrates they can burn. The less active, the smaller the muscles, and the more sedentary the lifestyle, the more important it becomes to limit carbohydrate intake to prevent overweight and its negative health consequences.

Erasmus stresses healthy fats. "The first truth about fats is that they do not make us fat. This is because they suppress appetite, and because eating fats does not produce the blood sugar swings, the insulin spiking, the fat production, the inhibition of fat burning, the craving, and the bingeing cycles produced by carbohydrates. The second truth is that certain fats, especially (omega-3 essential fats) which are too low in 99% of the population help us lose body fat."

DR. UDO ERASMUS' FOOD PYRAMID

As you can see, Erasmus stresses greens, non-starchy vegetables, and plant oils like Harvard does, but de-emphasizes carbohydrates (pasta, rice & fruit), even whole grains. They both relegate red meat, starchy vegetables like potatoes, and refined foods to the top (i.e., small proportions). READ MORE

Arguably, no diet has been as controversial as the Atkin's High Protein Diet. The LOW-CARB-HIGH PROTEIN PYRAMID recommends much higher proportions of protein and fat, and low percentages of carbohydrates and vegetable oils of any kind.

HIGH PROTEIN - LOW CARB FOOD PYRAMID

The case for low-carbohydrate diets is gaining weight. The Harvard School of Public Health concluded that higher-protein diets increase short-term weight loss and improve blood lipids, and lower risk of hypertension and coronary heart disease. However, different sources of protein appear to have different effects on cardiovascular disease. And that epidemiologic studies suggest that the effects of protein-rich foods on cardiovascular risk are not entirely driven by saturated fat and cholesterol. - [American Journal of Clinical Nutrition, Vol.82,No. 1,242S-247S,JUL05.]

In MAR07, researchers at the Stanford University School of Medicine completed the longest-ever comparison of four popular (Atkins, The Zone - about equal carb-protein-fat, The LEARN - USDA's guidelines, The Ornish - high carb/very low fat) diets, and the lowest- carbohydrate Atkins diet came out on top. READ MORE

Many proponets of these various diets cite foods with their glycemic value. There is research that shows that eating the right kinds of carbohydrates is the key to long-term health, reducing the risk of heart disease and diabetes, and sustainable weight loss. There are different kinds of carbohydrate foods and they effect our bodies differently. The glycemic index or GI numerically ranks carbohydrates according to their effect on blood glucose levels. The concept, developed by Dr. David J. Jenkins in 1981 at the University of Toronto, says that choosing low GI carbs - the ones that produce only small fluctuations in our blood glucose and insulin levels - is the key to a healthy diet.

A GI value tells you only how rapidly a particular carbohydrate turns into sugar. (Recent studies indicate that neither protein nor fat have more than a minuscule affect on blood glucose.) It doesn't tell you how much of that carbohydrate is in a serving of a particular food. Therefore, you need to know both things to understand a food's effect on blood sugar. That is where the glycemic load (GL) factors in. The GL is a way to assess the impact of carbohydrate consumption that takes the GI into account, but gives a more accurate picture than does glycemic index alone. For example, the carbohydrate in watermelon has a high GI. But there isn't a lot of it in a slice, so watermelon's glycemic load is relatively low. When comparing GLs, a GL of 20 or more is considered high, a GL of 11 to 19 is medium, and a GL of 10 or less is low. READ MORE

Unfortunately for the consumer, there are conflicting studies about the efficay of Low-GI and High-GI diets on weight loss. For example, a study from the Jean Mayer US Department of Agriculture Human Nutrition Research Center on Aging at Tufts University, Boston, MA concludes that "diets differing substantially in glycemic load induce comparable long-term weight loss." READ MORE

Macrobiotics is one of the more popular dietary approaches to cancer (although there is limited scientific evidence to support this claim). A macrobiotic diet is generally vegetarian...a Japanese peasant diet in nature. It is similar to both the Mediterranean and Asian Food diets, except for its very limited use of poultry and other mammals' meat, dairy products, fruits, fruit juice, nuts, and honey.

This regime emphasizes whole grain cereals; legumes (especially beans and bean products, such as tofu and tempeh; cooked and raw vegetables; seaweed; and fermented soy products (eg., miso and tamari); a variety of cooked and raw vegetables; mild natural seasonings; mild (non-stimulating) beverages, such as bancha twig tea; and a limited amount of animal food. The diet avoids highly processed or refined foods. Many practitioners avoid or sparingly use nightshade vegetables (tomatoes, peppers, potatoes, and eggplants) - as they are considered extremely "yin." READ MORE

Contrary to most people's understanding, there is no such thing as 'bad' cholesterol and 'good' cholesterol. Cholesterol is a necessary ingredient that is required to be regularly delivered around the body for the efficient healthy development, maintenance and functioning of our cells. The difference is in the 'transporters' (the lipoproteins HDL and LDL) that carry the cholesterol around the body. LDL carries dietary cholesterol from the liver to various parts of the body; and HDL takes cholesterol back to the liver where any unnecessary excess can be processed for elimination. Both types are essential for the human body's delivery system to work effectively. The cholesterol itself remains exactly the same. Problems occur when the LDL particles are both small and their carrying capacity outweighs the transportation potential of available HDL. Without any way for returning excess cholesterol to the liver, excess cholesterol remains in the blood and transported around the body. That's why they're referred to as "bad." READ MORE

Few people can or will strictly adhere to the exact proportions of a particular dietary pyramid. That's OK, after all they are just guidelines. The human body is miraculously designed. Biologically, you can eat just about anything. But your body plays it safe in case you fall on hard times. It will store just about everything you don't burn off. So eat sensibly and burn it off (exercise), otherwise excess calories, whether from sugars, fats, proteins or carbohydrates, will be converted and stored as fat.

Dr. Barbara Rolls is one of the leading researchers on weight management. Consumer Reports rated Volumetrics as the number one diet in terms of sustainable weight loss. Rolls teaches and performs nutrition research at Penn State University, where she holds the endowed Guthrie Chair of Nutritional Sciences. Her studies demonstrate that people can eat hundreds of calories less per day, lose weight and not feel hungry or deprived through a process she cals "volumetrics". Volumetrics is based on "the science of satiety"-- in other words the food choices that make people feel full.

Rolls noticed that despite the macronutrients involved, (carbohydrates, protein and fat) people still ate the same amount of food each day. What was different and what caused people to gain weight was that they ate different caloric amounts. Therefore, since people tend to eat a specific daily volume of food, she teaches that by eating low-calorie-dense, high-volume foods with high water and fiber content makes you feel like you've eaten plenty, even though you've eaten fewer calories. In other words, fruits, vegetables, and soups—all high in water content—are low in energy density, and therefore allowed in greater quantities. These foods tend to be more filling, so you eat less—and that's how easy weight loss can result.

Dr. Rolls categorizes foods according to their "density" (the amount of calories per gram of food). Category 1 is the least energy dense having the fewest calories per gram (fruits, most vegies, oatmeal, low-fat dairy, etc.); Category 2 (fish, chicken w/o skin, potatoes, pasta, rice, beans, etc.); Category 3 (raisins, hard pretzels, oil packed tuna etc.); and Category 4 - high energy dense foods (bacon, butter, pecans etc.) If you select the lower energy dense foods most of the time and add select portions of the high energy dense and nutritious foods you will lose weight. Her research showed that subjects could eat up to 800 calories LESS per day and not even notice the difference if they made the right choices.

So, if you started off your meal with a fruit salad of sliced apples, strawberries and pineapple slices, you have supplied your body with water, fiber and vitamins and have started moving your brain's satiety gauge towards the 'full' position. Then by following this starter with veggies, soup and finishing with small portins of the main fare, your brain registers the fact that you have provided your body enough nutriments and that you are tank is "full." With volumetrics you are not micromanaging your nutrients, i.e. tracking no-fat or protein-rich foods, nor are you giving up favorite foods like chocolate, bread or cheese. In fact, the plan allows you to indulge in your favorite foods so you're much more likely to stick to the program. And since these foods are consumed at the end of the meal after your brain has signaled that you're full, you'll eat less of these high-calorie foods. Basically, Rolls provides no special foods or restrictions--she provides a weight-loss strategy that reduces caloric intake in a way you can feel satisied when eating.