The Science of Obesity: Fats and Cholesterol.
For years we heard that a low-fat, low-cholesterol diet would keep us healthy and help us lose weight. And many of us jumped on the bandwagon, eliminating fat and high-cholesterol foods from our diets. Well, unfortunately, we were doing it all wrong.
Instead of eliminating fat completely, we should have been eliminating the "bad fats," the fats associated with obesity and heart disease and eating the "good fats," the fats that actually help improve blood cholesterol levels. Before we examine the good fats and bad fats, let's talk about cholesterol.
Cholesterol - It's been ingrained into our brains that cholesterol causes heart disease and that we should limit our intake of foods that contain it, but dietary cholesterol is different than blood cholesterol. Cholesterol comes from two places first, from food such as meat, eggs, and seafood, and second, from our body. Our liver makes this waxy substance and links it to carrier proteins called lipoproteins. These lipoproteins dissolve the cholesterol in blood and carry it to all parts of your body. Our body needs cholesterol to help form cell membranes, some hormones, and Vitamin D.
You may have heard of "good" and "bad" cholesterol. Well, high-density lipoproteins (HDL) carry cholesterol from the blood to the liver. The liver processes the cholesterol for elimination from the body. If there's HDL in the blood, then less cholesterol will be deposited in the coronary arteries. That's why it's called "good" cholesterol.
Low-density lipoproteins (LDL), carry cholesterol from the liver to the rest of the body. When there is too much in the body, it is deposited in the coronary arteries. This is not good. A build-up of cholesterol in our arteries could prevent blood from getting to parts of our heart. That means that our heart won't get the oxygen and nutrients it needs, which could result in heart attack, stroke, or sudden death. So, if your LDL is higher than your HDL, you're at a greater risk for developing heart disease.
It may come as a surprise, but recent studies have shown that the amount of cholesterol in our food is not strongly linked to our blood cholesterol levels. It's the types of fats you eat that affect your blood cholesterol levels.
Bad Fats - There are two fats that you should limit your intake of saturated and trans fats.
Saturated Fats - Saturated fats are mostly animal fats. You find them in meat, whole-milk products, poultry skin, and egg yolks. Coconut oil also has a high amount of saturated fat. Saturated fats raise both the good and bad blood cholesterol.
Trans Fats - Trans fats are produced through hydrogenation heating oils in the presence of oxygen. Many products contain trans fats because the fats help them maintain a longer shelf life. Margarine also contains a high amount of trans fats. Trans fats are especially dangerous because they lower the good cholesterol, HDL and raise the bad cholesterol, LDL. Unfortunately, most products do not tell you how much trans fat it contains, but you can find out if it's in a product by looking at the ingredient list. If the ingredients contain hydrogenated or partially-hydrogenated oils, then it contains trans fats. Fortunately in 2006, manufacturers will be required to list the amount of trans fat in their products on the nutrition labels, so it will be easier for you to find.
Good Fats - Some fats actually improve cholesterol levels.
Polyunsaturated Fats - Polyunsaturated fats are found in sunflower, corn, and soybean oils. These oils contain Omega-6, an essential fatty acid. However, most people get enough Omega-6 in their diet and instead need more Omega-3. Omega-3 is a fatty acid found in fish and walnuts.
Monounsaturated Fats - Monounsaturated fats are found in canola, peanut, and olive oils.
Both types of unsaturated fats decrease the bad cholesterol, LDL and increase the good cholesterol, HDL.
Now, just because the unsaturated fats improve your blood cholesterol levels, you don't have the go-ahead to eat all of the olive oil, butter and nuts you want. Fat of any kind does contain calories, and if you're trying to lose weight, eat fat in moderation, and stay away from saturated fats.
UNDERSTANDING YOUR WEIGHT
A pound of fat represents approximately 3500 calories of stored energy. In order to lose a pound of fat, you have to use 3500 more calories than you consume. Although this seems like a simple formula remember that your body is a thinking organism designed to protect itself. If you were to try to reduce your intake by the entire 3500 calories in one day, your body would register some type of alarm and think that there is a state of emergency. Immediately your metabolism would slow down and no weight loss would be achieved. It's better to spread your weight loss out over a period of a week, so that you aim to reduce your caloric intake by 3500 to 7000 calories per week, resulting in weight loss of one to two pounds per week. It's generally not recommended to try to lose more than two pounds in a week. Attempting to do so may cause health risks, and on top of this you're unlikely to be successful.
In the example of attempting to lose two pounds per week, you can use a basic method of calorie counting to help you accomplish your goal. To do so, you need to figure out how many calories a person of your age, sex, and weight usually needs in a day, subtract 500 from that amount, and follow a diet that provides you with that many calories. For example, if you would ordinarily need 3000 calories in a day, you would follow a 2500-calorie a day diet. Next, figure out how much exercise a person of your weight would need to do to burn 500 calories per day, and engage in an exercise plan that will help you achieve your goal. The result is simple: 500 fewer calories consumed and 500 more calories expended equals a 1000 calorie per day deficit, which, over the course of a week adds up to 7000 calories, or two pounds. Although individual results may vary, the bottom line is if your body is consuming fewer calories than it's expending, then weight will be lost.
HOW TO CALCULATE YOUR NEEDS
In order to eat fewer calories than
you need, you have to determine how many calories you actually need. Adults can calculate their approximate energy
needs using the following formula:
Adult females can calculate their approximate energy needs using the same formula, except that the "Basal Metabolic Rate" is determined by multiplying body weight times 11 instead of 12. Children and teenagers require more calories by body weight, but the amount varies by age and by individual child. It is best to consult a physician before altering a child's diet, however activity and exercise increases won't hurt the average youth of today, and will show some benefits of controlling obesity.
Overall, this gives you a general idea of what a calorie is, how it relates to weight, and how the body turns calories into fat. This is not of course a complete diet plan. However understanding your body is a definite prerequisite to making the changes necessary to conquer obesity.