Pritikin diet

02May07

The Pritikin Diet was created by Nathan Pritikin and enhanced by his son Robert Pritikin. It is a low-fat, high carbohydrate diet. (cf. Atkins diet)

The Pritikin Program was often described by Nathan Pritikin, its creator, as “mankind’s original meal plan.” That’s because the focus of the Pritikin diet is unprocessed or minimally processed straight-from-nature foods like fruits, vegetables, legumes (such as black beans and pinto beans), whole grains such as brown rice, starchy vegetables like potatoes and yams, lean meat, and seafood.

The Pritikin Program also emphasizes another key characteristic of humankind up until the last century: plenty of daily exercise, including at least 30 minutes of aerobic exercise like brisk walking, weight training two to three times weekly, and stretching, optimally every day.

This return to basics may be precisely what’s needed to return affluent societies to good health. In several studies published since 1975, scientists at UCLA and other research institutions have found the Pritikin Program effective in preventing the major diseases that afflict modern society, such as heart disease, type 2 diabetes, hypertension, and obesity. The Pritikin Program has been documented to improve cholesterol profiles better than cholesterol-lowering drugs like statins, and has also been found to lower blood sugars, normalize blood pressure, and shed excess weight.


The practice of the Pritikin Diet holds that in order to feel satisfied and stop eating, a human being needs to consume enough food, of any sort, until he has ingested a certain amount of bulk, that is, physical weight. Fat, as a food source, is not unhealthy in itself; it is necessary to good health. Fat contains more calories per pound, however, than carbohydrates, and therefore eating fat is essentially choosing more calories for the same amount of “fullness” according to Pritikin’s hunger satisfaction theory. The result: a given quantity of fat adds more calories for the same amount of fullness provided by an equal weight of food from other sources.

The stomach and the body, according to Dr. Pritikin’s theory, do not “know” whether the bulk ingested consists of fat or anything else. The body knows only whether it has obtained sufficient bulk to feel sated. Hence the Pritikin principle advocates a low-density, high-bulk diet. This means a diet rich in fruit, vegetables, lean meats and fish, and plenty of nonsoluble fiber, all of which generally promote good health. Processed, high-fat foods, on the other hand, should be avoided–not simply because they have additives and artificial ingredients–but rather because they are low-bulk and high-calorie.

The Pritikin Diet was most popular in the 1970s and is less so today. The Pritikin Diet calls for balanced meals with foods of recognized nutritional value: fresh vegetables, fruit, and above all fiber–which reduces the risks of colon cancer and helps the body remove cholesterol.


The Paleolithic diet, also known as the caveman diet, paleo diet, prehistoric diet, Stone Age diet, or hunter-gatherer diet, is the diet of wild plants and animals that various human species habitually consumed during the Paleolithic period (the Old Stone Age), a period of about 2 million years duration, ending about 10,000 years ago, when our species, Homo sapiens, invented agriculture. The modern version of this diet, the Paleolithic Diet, uses domesticated sources in lieu of the wild sources of the original hunter-gatherer diet.

Those who advocate that contemporary humans should regularly consume a Paleolithic diet base their advocacy on the premise that natural selection had 2 million or more years to genetically adapt the metabolism and physiology of the various human species to such a diet, and that in the 10,000 years since the invention of agriculture and its consequent major change in the human diet, natural selection has had too little time to make the optimal genetic adaptations to the new diet. According to those advocates, physiological and metabolic maladaptations result from those suboptimal genetic adaptations, which in turn contribute to many of the so-called diseases of civilization.

Those considerations give rise to a simple theme for adhering to a Paleolithic-type diet in modern times: if a food item resembles one that can be found in the wild, obtained with bare hands or simple tools, and ingested immediately without cooking, processing, and by simple preparation (i.e., peeling, cracking, washing, etc.), and cause the consumer no ill effects either during or after consumption, then it can be considered edible, and therefore permissible to eat. Any food meeting this standard can then be cooked and prepared by the simplest means as practical and consumed in modest quantities. Food exclusions comprise those introduced in the human food supply late in the course of human evolution, in particular after the invention of agriculture about 10,000 years ago: cereal grains, legumes and dairy products.


Dieting

02May07

Dieting is the practice of ingesting food in a regulated fashion to achieve a particular objective. In many cases the goal is weight loss, but some athletes aspire to gain weight (usually in the form of muscle) and diets can also be used to maintain a stable body weight.


There are several kinds of diets:

* Weight-loss diets restrict the intake of specific foods, or food in general, to reduce body weight. What works to reduce body weight for one person will not necessarily work for another, due to metabolic differences and lifestyle factors. Also, for a variety of reasons, most people find it very difficult to maintain significant weight loss over time. There is some thought that losing weight quickly may actually make it more difficult to maintain the loss over time.

* Many professional athletes impose weight-gain diets on themselves. American football players may try to “bulk up” through weight-gain diets in order to gain an advantage on the field with a higher mass.

Many people in the acting industry may choose to lose or gain weight depending on the role they’re given.


According to the principles of thermoregulation, humans are endotherms. We expend energy to maintain our blood temperature at body temperature, which is about 37 °C (98.6 °F). This is accomplished by metabolism and blood circulation, by shivering to stay warm, and by sweating to stay cool.

In addition to thermoregulation, humans expend energy keeping the vital organs (especially the lungs, heart and brain) functioning. Except when sleeping, our skeletal muscles are working, typically to maintain upright posture. The average work done just to stay alive is the basal metabolic rate, which (for humans) is about 1 watt per kilogram (2.2 lbs) of body mass. Thus, an average man of 75 kilograms (165 lbs) who just rests (or only walks a few steps) burns about 75 watts (continuously), or about 6,500 kilojoules (1,500 Calories) per day.


Physical exercise is an important complement to dieting in securing weight loss. Aerobic exercise is also an important part of maintaining normal good health, especially the muscular strength of the heart. To be useful, aerobic exercise requires maintaining a target heart rate of above 50 percent of one’s resting heart rate for 30 minutes, at least 3 times a week. Brisk walking can accomplish this.

The ability of a few hours a week of exercise to contribute to weight loss can be somewhat overestimated. To illustrate, consider a 100-kilogram man who wants to lose 10 kilograms and assume that he eats just enough to maintain his weight (at rest), so that weight loss can only come from exercise. Those 10 kilograms converted to work are equivalent to about 350 megajoules. (We use an approximation of the standard 37 kilojoules or 9 Calories per gram of fat.) Now assume that his chosen exercise is stairclimbing and that he is 20 percent efficient at converting chemical energy into mechanical work (this is within measured ranges). To lose the weight, he must ascend 70 kilometers. A man of normal fitness (like him) will be tired after 500 meters of climbing (about 150 flights of stairs), so he needs to exercise every day for 140 days (to reach his target). However, exercise (both aerobic and anaerobic) would increase the Basic Metabolic Rate (BMR) for some time after the workout. This ensures more calorific loss than otherwise estimated.

The minimum safe dietary energy intake (without medical supervision) is 75 percent of that needed to maintain basal metabolism. For our hypothetical 100-kilogram man, that minimum is about 5,700 kilojoules (1,300 calories) per day. By combining daily aerobic exercise with a weight-loss diet, he would be able to lose 10 kilograms in half the time (70 days). Of course, the described regime is more rigorous than would be desirable or advisable for many persons. Therefore, under an effective but more manageable weight-loss program, losing 10 kilograms (about 20 pounds) may take as long as 6 months.

There are also some easy ways for people to exercise, such as walking rather than driving, climbing stairs instead of taking elevators, doing more housework with fewer power tools, or parking their cars farther and walking to school or the office.




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