Wiki Dieting
Dieting
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Measuring body weight on a scale
Measuring body weight on a scale
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.
Contents
[hide]
* 1 Types of dieting
* 2 History of targeted dieting
* 3 Thermoregulation
* 4 Physical exercise
* 5 Fat loss versus muscle loss
* 6 Energy obtained from food
* 7 Proper nutrition
* 8 How the body gets rid of fat
* 9 Psychological aspects of weight-loss dieting
* 10 Weight loss groups
* 11 Popular weight-loss diets
o 11.1 Low-fat diets
o 11.2 Atkins (low-carbohydrate diet)
o 11.3 Natural diets
o 11.4 Vegetarian diet
o 11.5 Weight Watchers
* 12 Very Low Calorie Diet
* 13 Dangers of weight loss dieting
o 13.1 Diet pills
o 13.2 Yo-yo dieting
o 13.3 Dangers of fasting
o 13.4 Side effects
* 14 See also
* 15 References
* 16 External links
[edit] Types of dieting
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. It is also possible that cutting calorie intake too low slows or prevents weight loss. The National Institutes of Health notes that the commonly recommended program of reduced caloric intake along with increased physical activity has a failure rate of 98%.
* 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.
[edit] History of targeted dieting
See Luigi Cornaro for a 16th century treatise on dieting. Throughout the 17th and 18th centuries, physicians and patients regulated their food carefully, in order to prevent disease.[citation needed] In the 19th century, as the scientific classification of foods took shape, doctors and scientists began experimenting with targeted diets.
William Banting is one of the first people known to have successfully lost weight by developing a targeted diet, circa 1863, by targeting carbohydrates. The low carbohydrate diet, sometimes marketed today as the Atkins Diet, remains popular today.
[edit] Thermoregulation
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.[1]
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.
[edit] Physical exercise
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 maximum 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 (220 lbs) man who wants to lose 10 kilograms (22 lbs) and assume that he eats just enough to maintain his weight (at rest), so that weight loss can only come from exercise. Those 10 (22 lbs) 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.
From Wikipedia, the free encyclopedia
Jump to: navigation, search
Measuring body weight on a scale
Measuring body weight on a scale
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.
Contents
[hide]
* 1 Types of dieting
* 2 History of targeted dieting
* 3 Thermoregulation
* 4 Physical exercise
* 5 Fat loss versus muscle loss
* 6 Energy obtained from food
* 7 Proper nutrition
* 8 How the body gets rid of fat
* 9 Psychological aspects of weight-loss dieting
* 10 Weight loss groups
* 11 Popular weight-loss diets
o 11.1 Low-fat diets
o 11.2 Atkins (low-carbohydrate diet)
o 11.3 Natural diets
o 11.4 Vegetarian diet
o 11.5 Weight Watchers
* 12 Very Low Calorie Diet
* 13 Dangers of weight loss dieting
o 13.1 Diet pills
o 13.2 Yo-yo dieting
o 13.3 Dangers of fasting
o 13.4 Side effects
* 14 See also
* 15 References
* 16 External links
[edit] Types of dieting
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. It is also possible that cutting calorie intake too low slows or prevents weight loss. The National Institutes of Health notes that the commonly recommended program of reduced caloric intake along with increased physical activity has a failure rate of 98%.
* 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.
[edit] History of targeted dieting
See Luigi Cornaro for a 16th century treatise on dieting. Throughout the 17th and 18th centuries, physicians and patients regulated their food carefully, in order to prevent disease.[citation needed] In the 19th century, as the scientific classification of foods took shape, doctors and scientists began experimenting with targeted diets.
William Banting is one of the first people known to have successfully lost weight by developing a targeted diet, circa 1863, by targeting carbohydrates. The low carbohydrate diet, sometimes marketed today as the Atkins Diet, remains popular today.
[edit] Thermoregulation
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.[1]
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.
[edit] Physical exercise
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 maximum 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 (220 lbs) man who wants to lose 10 kilograms (22 lbs) and assume that he eats just enough to maintain his weight (at rest), so that weight loss can only come from exercise. Those 10 (22 lbs) 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.
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