With all the new trends in dieting that come and go over the years, no two diets have been more at odds with one another or sparked more controversy than the low-fat and low-carb diets. This article describes both, including the pros and cons of each, and compares them with common-sense nutrition.
The Low-Fat Diet
The low-fat diet was first introduced by Nathan Pritikin, an engineer, in the 1950s. After being diagnosed with heart disease, he decided to change his diet and developed an approach to eating that limited dietary fat intake to less than 10% of daily calories. By the 1970s, Pritikin had appeared on 60 Minutes and soon became a household name.
The Pritikin, or low-fat, diet places an emphasis on whole grains, fruits and vegetables, with very little protein from lean sources. Dairy products are limited to skim milk and other fat-free products (such as fat-free dressings and yogurt). Most animal fats and other saturated fats such as butter are off limits. Egg whites are acceptable in small quantities (no more than two per day), but the whole egg and egg yolks are forbidden.
The ideal low fat diet is also low in calories and includes:
*Five or more servings of whole grains and starchy vegetables (about 800 calories)
*Five servings of fresh vegetables (about 125 calories)
*Four servings of fresh fruit (about 120 calories)
*Two servings of nonfat calcium rich foods per day (up to 200 calories)
*No more than one serving (3-1/2 ounces) of animal protein (less than 100 calories)
The above list comes to less than 1400 calories per day. This is extremely low, even for dieting standards. While the low fat diet will help you lose weight, this is due mostly to calorie restriction. Many find it very difficult to maintain this method of eating permanently. Supporters of the low fat diet claim this is more in line with the way our ancestors ate, focusing primarily fruits and vegetables.
The Low Carb Diet
Coincidentally, the low carb diet became popular about the same time as the low fat diet. It was developed by a cardiologist, Dr. Robert Atkins. He used this method initially to help his heart patients who needed to lose weight before undergoing heart surgery. Interestingly, supporters of the Atkins diet make the same claim that the low fat dieters do, that this method is more in line with the way our ancestors ate, focusing primarily on protein rich meats, fish, with little to no grains. It should be noted here that humans have been cultivating grains for food little more than 8,000 years. Most scientist teach that humans (homo sapien) have been on Earth for around 200,000 years. If that is true, then grains have been a part of the human diet for less than 5% of our existence.
The low carb diet does not exclude carbohydrates completely but places an emphasis on proteins and fresh vegetables. The Atkins diet as published originally also called for some whole grains, including millet, a high-protein grain. The newer versions of the low carb diet do make the distinction between "good" carbs and "bad" carbs. The basic low carb diet includes:
All meats, fish, eggs and cheese.
Fresh vegetables
Initially less than 20 grams of carbohydrates per day (mostly from vegetables), and ultimately less than 100 grams of carbohydrates per day (which includes some whole grains and starchy vegetables)
In the first phase of the low carb diet, all fruits, grains and sugars are avoided. After two weeks you can slowly introduce starchy vegetables such as squashes and potatoes, and eventually a limited amount of whole grains. Processed sugars and processed grains should be avoided indefinitely.
There is no calorie counting with most low carb diets. The only counting done is that of carbohydrates, which is very restricted. While the calories are much higher on the low carb diet, most people still lose weight. This is due primarily to ketosis. The body has two methods of producing energy: glycolysis, which utilizes glucose, and ketosis, which utilizes fat stores. Some experts warn that the human body was not made to stay in a state of ketosis all the time and that it can be stressful on the kidneys.
While the high protein, high fat content of the low carb diet is more satiating, some still claim this can be a difficult method to follow long term. Our modern diet is filled with carbohydrates. We "break bread" together. It would be challenging to eliminate complex carbohydrates from the diet indefinitely.
Basic Nutrition
The human body requires three major components, or macronutrients, in order to function properly: carbohydrates, proteins and fats. Any diet, no matter how well intended or fine tuned, that severely restricts any one of these macronutrients will eventually lead to deficiency or even malnutrition. Each of these components can be broken down.
Carbohydrates
Carbohydrates can be classified into two categories, simple and complex. Both are broken down into glucose in the digestive system, which is then utilized for energy production. In other words, carbohydrates give us energy. Simple sugars are absorbed quickly into the bloodstream and provide a quick source of energy but are expended within about an hour. Complex carbohydrates take longer, around 4 hours to completely break down, and therefore provide a more efficient source of energy.
However, excess carbohydrates are not simply eliminated from the body. If unused, the body converts them into fat to be stored for future use. If properly examined, most overweight individuals will find their diets are not high in fats but in carbohydrates. The highest calorie sources of carbohydrates are processed snack foods, soda, candy and desserts. These are often referred to as "junk food" for good reason. They provide little nutrition, and most people cannot burn all the calories from these tasty treats consumed at one time.
Examples of simple carbohydrates include fruit, sugar, honey, syrup, lactose (the sugars found in milk) and fructose. Examples of complex carbohydrates include starchy vegetables such as corn and potatoes, and whole grains such as whole wheat and brown rice. Whole grains and vegetables also provide the body with other vitamins and minerals, including certain B vitamins, vitamins A, C and K, as well as trace minerals such as calcium and magnesium.
Proteins
Proteins are made up of smaller components called amino acids. They are the building blocks of the body. Proteins are found in just about every structure of the body, including muscle, skin, organs and tissues. During digestion, the proteins are broken down into individual amino acids, which are utilized by the body. There are 8 essential amino acids, meaning they must be obtained from protein sources in the diet, and there 12 nonessential amino acids, meaning they are manufactured by the body.
Sources of dietary protein include meat, fish, eggs, dairy, legumes (lentils, beans and soy), nuts, and seeds. Trace amounts can be found in grains and some vegetables. However, only soy and animal sources contain all essential amino acids. Strict vegetarians must be careful to combine the correct plant sources in order to obtain a complete protein. This can be accomplished by combining a whole grain and a legume, for example, or by including soy in the diet.
A diet deficient in protein can result in muscle weakness, hair loss, dry skin, anemia (iron deficiency) and edema. More serious cases of protein deficiency cause diseases such as Marasmus and Kwarshiorkor, which are common in third-world countries and areas of poverty. Foods high in protein (like dairy, meat and eggs) also provide other essential nutrients and vitamins, such as vitamins A, D and E, as well as iron and the trace mineral chromium.
Dietary Fats
Dietary fats are known as lipids. Every cell in the body contains lipids, and as such, fats are an essential part of the diet. The brain is mostly fat. Fats are responsible for the manufacturing and regulation of many hormones. And, much like carbohydrates, can be used as fuel for the body. At more than twice the caloric value of carbohydrates and proteins, fats provide an efficient source for energy. They take much longer to be broken down in the digestive system, up to 12 hours, and therefore provide a longer, sustainable form of energy.
Some confuse cholesterol with fat. Please note, cholesterol is not fat! Cholesterol is a hormone that is carried through the bloodstream by proteins: high density lipo-proteins and low density lipo-proteins. Each serves an important function in the body. While certain foods do contain cholesterol, it is also made in the liver. The cholesterol in the bloodstream is not necessarily cholesterol that was obtained from the diet. Fats are generally categorized as saturated and unsaturated. This refers to the saturation of hydrogen atoms in the fat molecules. In other words, saturated fats are more densely packed with hydrogen. Both types are used by the body.
Lipids (fats) are important in the regulation hormones such as cholesterol, serotonin, leptin (which tells the body when to eat and when it is satisfied) and adenopecton (involved in both glucose and lipid metabolism). Additionally, fats are required to assimilate the fat-soluble vitamins: A, D, E and K and are needed for the absorption of certain trace minerals.
A diet lacking adequate fat will cause serious health risks, some of which are the result of lack of absorption of the fat-soluble vitamins and minerals. Some signs of lack of fat in the diet are memory loss, lack of concentration, depression, fatigue and hormonal imbalances.
Some examples of dietary fats are:
Animal fat, dairy, eggs (saturated)
Butter (saturated)
Nuts and seeds (unsaturated)
Olive oil (unsaturated)
Coconut oil (saturated)
Avocado (saturated)
The only fats that have conclusively shown to be dangerous or that pose serious health risks are trans-fats. Trans-fats are fats that have been altered at the molecular level. This is usually the result of extreme temperatures and pressure, or by adding hydrogen to an oil to make it more stable (a process called hydrogenation). There is recent evidence that even links trans-fats to certain cancers. Trans-fats are found in margarine, hydrogenated oils like vegetable oil and shortening, as well as many snack foods, cookies, peanut butter and deep-fat fried foods.
Fad Diets Lead to Deficiencies
While fad diets such as the low carb or low fat diet may help you lose weight initially, they are not permanent, healthy methods of eating. Remember that humans require three major components in their diet: carbohydrates, proteins and fats. Any diet that severely restricts are forbids any one of these macronutrients will eventually lead to dietary deficiency and pose health risks. A serious study of the human diet over the past 200,000 years will show that humans have survived on animals and native plants, nuts and seeds. It was not until recently that we began cultivating and processing grains for food.
If you are concerned about your health or need to lose weight, eat a more "natural" diet, one that includes proteins (meat, eggs and/or dairy, nuts, seeds and legumes), carbohydrates (whole grains, vegetables, fruits, potatoes) and fats (butter, natural oils, nuts and seeds). These should each be eaten in moderation. Avoid all processed foods, snack foods (chips, cookies), sugary foods (candy, soda) and especially foods with trans-fats.
Lastly, too much can never be said for exercise. Find some form of exercise to do each day, and drink plenty of water. A sensible, balanced diet along with moderate exercise will ultimately help you find a healthy weight that is right for you. Your "diet" should not be a temporary solution but a change you can live with for a lifetime.
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