Dieting is the practice of ingesting food in a regulated fashion to achieve or maintain a controlled weight. A weighing scale (usually just "scale" in common usage except in Australian English where "scales" is more common is a Measuring instrument for In general terms eating (formally ingestion) is the process of consuming Food to provide for the Nutritional needs of an Animal, particularly In most 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. Weight loss, in the context of Medicine or Health or Physical fitness, is a reduction of the total Body weight, due to a mean loss of fluid Skeletal muscle is a type of Striated muscle, which usually attaches to tendons

Contents 1 Types of dieting 2 In children and young adults 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 Dangers 11.1 Medications 11.1.1 Diuretics 11.1.2 Stimulants 11.2 Dangers of fasting 11.3 Side effects 12 See also 13 References 14 External links

Types of dieting

There are several kinds of diets:

• Weight-loss diets restricts 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 metobalithic. differences and lifestyle factors. Also, for a variety of reasons, most people find it difficult to maintain significant weight loss over time — among individuals that have lost 10% or more of body weight, only 20% are able to maintain that weight loss for a full year. ^[1]

• 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.

• Individuals who are underweight, such as those recovering from anorexia nervosa or starvation, may adopt weight-gain diets which, unlike those of athletes, have the goal of restoring normal levels of body fat, muscle, and stores of essential nutrients. Anorexia Nervosa is a psychiatric Diagnosis that describes an Eating disorder characterized by low Body weight and Body image distortion Starvation (also called inanition) is a severe reduction in Vitamin, Nutrient, and Energy intake and is the most extreme form of

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

As more cultures scrutinize their diets, many parents consider putting their children on restricted diets that actually do more harm than good. This is extremely deleterious to a young child's health because a full and balanced diet (fats, carbohydrates, protein, vitamins, minerals, fiber, etc. ) is needed for growth. A doctor should be consulted before putting any child on a specialized diet.

Research also shows that putting children on diet foods can be harmful. The brain is unable to learn how to correlate taste with nutritional value, which is why such children may consistently overeat later in life despite adequate nutritional intake. ^[2]

In children and young adults

Receiving adequate nutrition through a well-balanced diet is critical during childhood and adolescence. Unless a doctor says otherwise, low-carb, low-fat, or other specialty diets for children who are not heavily obese are unhealthy because they deprive the body of the building blocks of cells (namely energy and lipids in the above examples). Lipids are broadly defined as any fat- Soluble ( lipophilic) naturally-occurring Molecule, such as fats oils waxes cholesterol sterols fat-soluble

Children who diet could actually be doing worse things for themselves and their bodies. Alison Field from Harvard Medical School stated that "Our study found that dieting was counterproductive- children who dieted gained more, not less, weight than non-dieters. " Scott,R. ,Jennifer "Dieting Kids May Gain Weight" 12,July,2006 [1] Children who diet tend to develop habits of overeating, or binge eating as a result of attempting to casually diet. It is suggested that children should just attempt to eat healthy instead of trying to casually diet.

Thermoregulation

According to the principles of thermoregulation, humans are endotherms. Thermoregulation is the ability of an Organism to keep its body temperature within certain boundaries even when temperature surrounding is very different In Biology, a warm-blooded Animal species is one whose members maintain thermal Homeostasis; that is they keep their body temperature at a roughly constant We expend energy to maintain our blood temperature at body temperature, which is about 37 °C (98. Core temperature, also called core body temperature, is the operating Temperature of an Organism, specifically in deep structures of the body such as the 6 °F). This is accomplished by metabolism and blood circulation, by shivering to stay warm, and by sweating to stay cool. ^[3]

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. Skeletal muscle is a type of Striated muscle, which usually attaches to tendons Posture or posturing may refer toIn humans Neutral spine or good posture Human position Abnormal posturing The average work done just to stay alive is the basal metabolic rate, which (for humans) is about 1 watt per kilogram of body mass (0. Basal metabolic rate ( BMR) is the amount of energy expended while at rest in a neutrally temperate environment in the post-absorptive state (meaning that the digestive system 45 W/lb). Thus, an average man of 75 kilograms (165 lb) who just rests (or only walks a few steps) burns about 75 watts (continuously), or about 6,500 kilojoules (1,440 kilocalories) per day or 1 kilocalorie each minute. The joule (written in lower case ˈdʒuːl or /ˈdʒaʊl/ (symbol J) is the SI unit of Energy measuring heat, Electricity This article is about the unit of energy For its use in Nutrition and Food labelling regulations, see the article on Food energy.

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. Aerobic exercise refers to Exercise that involves or improves oxygen consumption by the body Health is a state of complete physical mental and social well-being and not merely the absence of disease or infirmity Physical strength is the ability of a person or animal to exert Force on physical objects using muscles. To be useful, aerobic exercise requires maintaining a target heart rate of 50 percent above one's resting heart rate for 30 minutes, at least 3 times a week. Measuring heart rate The Pulse rate (which in most people is identical to the heart rate can be measured at any point on the body where an Artery 's pulsation Measuring heart rate The Pulse rate (which in most people is identical to the heart rate can be measured at any point on the body where an Artery 's pulsation Brisk walking can accomplish this. For example, if the resting heart rate is 70 bpm (beats per minute), the target heart rate would be 105 bpm. Always consult a physician before beginning any exercise program, and ask what the appropriate target heart rate for your physical condition and age should be.

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 lb) man who wants to lose 10 kilograms (22 lb) 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 (22 lb) converted to work are equivalent to about 350 megajoules (84,000 kilocalories). (We use an approximation of the standard 37 kilojoules or 9 kilocalories per gram of fat. Anyway, since the weight loss is also due to water loss, the actual loss will be slightly greater. ) 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 Basal 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 kilocalories) 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).

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.

Fat loss versus muscle loss

Weight loss typically involves the loss of fat, water and muscle. A dieter can lose weight without losing much fat. Ideally, overweight people should seek to lose fat and preserve muscle, since muscle burns more calories than fat. Generally, the more muscle mass one has, the higher one's metabolism is, resulting in more calories being burned. Approximately 14 kilocalories of fat are burned per pound of muscle at rest. Since muscles are more dense than fat, muscle loss results in little loss of physical bulk compared with fat loss. To determine whether weight loss is due to fat, various methods of measuring body fat percentage have been developed. An animal's total body fat percentage is the total weight of the animal's fat divided by the animal's weight and reflects both essential fat and storage fat

Muscle loss during weight loss can be restricted by regularly lifting weights (or doing push-ups and other strength-oriented calisthenics) and by maintaining sufficient protein intake. Calisthenics form a category of Physical exercises closely related to but not a part of Gymnastics. Proteins are large Organic compounds made of Amino acids arranged in a linear chain and joined together by Peptide bonds between the Carboxyl According to the National Academy of Sciences, the Dietary Reference Intake for protein is "0. The National Academy of Sciences (NAS is a corporation in the United States whose members serve Pro bono as "advisers to the nation on science The Dietary Reference Intake (or DRI is a system of Nutrition recommendations from the Institute of Medicine (IOM of the US National Academy of Sciences 8 grams per kilogram of body weight for adults. "

Those on low-carbohydrate diets, and those doing particularly strenuous exercise, may wish to increase their protein intake which is necessary. However, there may be risks involved. According to the American Heart Association, excessive protein intake may cause liver and kidney problems and may be a risk factor for heart disease. The American Heart Association (AHA is a Non-profit organization in the United States that fosters appropriate A risk factor is a variable associated with an increased risk of Disease or Infection. Heart disease is an Umbrella term for a variety for different diseases affecting the Heart. ^[4] There is no conclusive evidence that moderately high protein diets in healthy individuals are dangerous, however; it has only been shown that these diets are dangerous in individuals who already have kidney and liver problems.

Energy obtained from food

The energy humans get from food is limited by the efficiency of digestion and the efficiency of utilization. The efficiency of digestion is largely dependent on the type of food being eaten. Poorly chewed seeds are poorly digested. Refined sugars and fats are absorbed almost completely. Chewing does not compensate for the calorie content of a food that is eaten; even celery, which is primarily indigestible cellulose, contains enough sugars to easily compensate for the cost of chewing it. See also Wild celery Apium graveolens is a plant species in the family Apiaceae, and yielding celery and Celeriac Cellulose is an Organic compound with the formula, a Polysaccharide consisting of a linear chain of several hundred to over ten thousand β(1→4 Sugar is a class of edible Crystalline substances mainly Sucrose, Lactose, and Fructose.

Proper nutrition

Food provides nutrients from six broad classes: proteins, fats, carbohydrates, vitamins, dietary minerals, and water. Proteins are large Organic compounds made of Amino acids arranged in a linear chain and joined together by Peptide bonds between the Carboxyl Fats consist of a wide group of compounds that are generally soluble in organic solvents and largely insoluble in water Carbohydrates (from ' Hydrates of Carbon ' or saccharides ( Greek σάκχαρον meaning " Sugar " are the most A vitamin is an Organic compound required as a Nutrient in tiny amounts by an Organism. Dietary minerals are the Chemical elements required by living Organisms other than the four elements Carbon, Hydrogen, Nitrogen, and Water is a common Chemical substance that is essential for the survival of all known forms of Life. Carbohydrates are metabolized to provide energy. Proteins provide amino acids, which are required for cell, especially muscle, construction. In Chemistry, an amino acid is a Molecule containing both Amine and Carboxyl Functional groups In Biochemistry, this Essential fatty acids are required for brain and cell membrane construction. In Chemistry, especially Biochemistry, a fatty acid is a Carboxylic acid often with a long unbranched Aliphatic tail ( chain) which Vitamins and trace minerals help maintain proper electrolyte balance and are required for many metabolic processes. Dietary fiber is another food component which influences health even though it is not actually absorbed into the body. Dietary fibers are the indigestible portion of plant foods that move food through the Digestive system, absorbing water and easing Defecation.

Any diet that fails to meet minimum nutritional requirements can threaten general health (and physical fitness in particular). If a person is not well enough to be active, weight loss and good quality of life will be unlikely.

The National Academy of Sciences and the World Health Organization publish guidelines for dietary intakes of all known essential nutrients. The National Academy of Sciences (NAS is a corporation in the United States whose members serve Pro bono as "advisers to the nation on science

Sometimes dieters will ingest excessive amounts of vitamin and mineral supplements. While this is usually harmless, some nutrients are dangerous. Men (and women who don't menstruate) need to be wary of iron poisoning. See also "Mensuration" a term sometimes used to describe Measurement, particularly in the context of Forestry. Iron poisoning is caused by a large excess of Iron intake It has been primarily been associated with young children who consumed large quantities of iron supplement pills Retinol (oil-soluble vitamin A) is toxic in large doses. As a general rule, most people can get the nutrition they need from foods (there are specific exceptions; vegans often need to supplement vitamin B12). In any event, a multivitamin taken once a day will suffice for the majority of the population.

A sensible weight-loss diet is a normal balanced diet; it just comes with smaller portions and perhaps some substitutions (e. g. low-fat milk, or less salad dressing). Extreme diets may lead to malnutrition, and are less likely to be effective at long-term weight loss in any event.

How the body gets rid of fat

All body processes require energy to run properly. When the body is expending more energy than it is taking in (e. g. when exercising), the body's cells rely on internally stored energy sources, like complex carbohydrates and fats, for energy. The first source the body turns to is glycogen (by glycogenolysis). Glycogen is a Polysaccharide of Glucose (Glc which functions as the secondary short term energy storage in Animal cells Glycogenolysis (also known as "Glycogenlysis" is the Catabolism of Glycogen by removal of a Glucose monomer through cleavage with inorganic Glycogen is a complex carbohydrate (in total about 2000 kcal). 65% is stored in skeletal muscles and the rest in the liver. It is created from the excess of ingested macronutrients, mainly carbohydrates. A nutrient is food or chemicals that an organism needs to live and grow or a substance used in an organism's metabolism which must be taken in from its environment When those sources are nearly depleted, the body begins lipolysis, the mobilization and catabolism of fat stores for energy. Lipolysis is the breakdown of fat stored in fat cells During this process Free fatty acids are released into the bloodstream and circulate throughout the body In this process, fats, obtained from adipose tissue, or fat cells, are broken down into glycerol and fatty acids, which can be used to make energy. "Adipose" redirects here For the Doctor Who monster see " Partners in Crime " In Chemistry, especially Biochemistry, a fatty acid is a Carboxylic acid often with a long unbranched Aliphatic tail ( chain) which The primary by-products of metabolism are carbon dioxide and water; carbon dioxide is expelled through the respiratory system.

Fats are also secreted by the sebaceous glands (in the skin). The sebaceous glands are Glands found in the Skin of Mammals Locations and morphology A branched type of Acinar gland, these When losing weight one must be careful as to not begin to burn muscle. When the body runs of out of fats and carbohydrates to burn, it will begin to burn muscle which will be harmful for the body.

Psychological aspects of weight-loss dieting

Diets affect the "energy in" component of the energy balance by limiting or altering the distribution of foods. Techniques that affect the appetite can limit energy intake by affecting the desire to overeat.

Cognitive Behavior Therapy has been effective in producing long term weight loss ^[5]. See also Cognitive Therapy Cognitive Behavioral Therapy ( CBT) is an umbrella-term for psychotherapeutic systems that deal with cognitions interpretations Judith S. Beck has been one of the most prominent practitioners and writers to bring this method to a popular audience. Judith S Beck PhD (born May 5 1954 is an American Psychologist who is best known for her work in Cognitive therapy.

Consumption of low-energy, fiber-rich foods, such as non-starchy vegetables, is effective in obtaining satiation (the feeling of "fullness"). Exercise is also useful in controlling appetite as is drinking water and sleeping. (Extreme physical fatigue, such as that experienced by soldiers and mountain climbers, can make eating a difficult chore. )

The use of drugs to control appetite is also common. Stimulants are often taken as a means to suppress (normal, healthy) hunger by people who are dieting. Ephedrine (through facilitating the release of adrenaline and noradrenaline) stimulates the alpha(1)-adrenoreceptor subtype, which is known to act as an anorectic. Note "Anorectic" is also a term for an anorexic person a person suffering from Anorexia nervosa Anorectics, anorexigenics L-Phenylalanine, an amino acid found in whey protein powders also has the ability to suppress appetite by increasing the hormone cholecystokinin (CCK) which sends a satiety signal to the brain. Phe redirects here For the BitTorrent feature see PHE. For the constellation see Phoenix (constellation. Cholecystokinin ( CCK; from Greek chole, "bile" cysto, "sac" kinin, "move" hence move the bile-sac

Weight loss groups

There exist both profit-oriented and non-profit weight loss organizations who assist people in their weight loss efforts. An example of the former is Weight Watchers; examples of the latter include Overeaters Anonymous, as well as a multitude of non-branded support groups run by local churches, hospitals, and like-minded individuals. Weight Watchers ( is an international company that offers various Dieting products and services to assist Weight loss and maintenance Overeaters Anonymous ( OA) is a Twelve-step program for people with problems related to Food including but not limited to Compulsive overeaters

These organizations' customs and practices differ widely. Some groups are modelled on twelve-step programs, while others are quite informal. A twelve-step program is a set of guiding principles for recovery from Addiction, compulsion, or other behavioral problems Some groups advocate certain prepared foods or special menus, while others train dieters to make healthy choices from restaurant menus and while grocery-shopping and cooking.

Most groups leverage the power of group meetings to provide counseling, emotional support, problem-solving, and useful information.

Dangers

Extreme calorie restriction (fewer calories than 75% of that required for basal metabolic rate), medication or unusual patterns of eating (i. e. restricting food consumption to a single fruit or meal) can be dangerous. This can indicate Anorexia Nervosa and/or Bulimia which are common eating disorders and can even be fatal. Anorexia Nervosa is a psychiatric Diagnosis that describes an Eating disorder characterized by low Body weight and Body image distortion Bulimia nervosa is an Eating disorder characterized by recurrent Binge eating, followed by compensatory behaviors referred to as "purging" An eating disorder is a compulsion to eat or avoid eating that negatively affects both one's physical and mental health

Medications

Certain medications can be prescribed to assist in weight loss. Some, like amphetamines, are dangerous and are now banned for casual weight loss. Amphetamine, and related drugs such as Methamphetamine are a group of drugs that act by increasing levels of Norepinephrine, Serotonin, and Dopamine Some supplements, including those containing vitamins and minerals, may not be effective for losing weight. A vitamin is an Organic compound required as a Nutrient in tiny amounts by an Organism. A mineral is a naturally occurring substance formed through geological processes that has a characteristic chemical composition a highly ordered atomic structure and specific

Diuretics

Diuretics induce weight loss through the excretion of water. A diuretic is any Drug that elevates the rate of urination ( Diuresis) These medication or herbs will reduce the amount that a body weighs, but will have no effect on an individual's body fat. A(n herb (ˈhɝb or /ˈɝb/ see pronunciation differences) is a plant that is valued for qualities such as medicinal properties flavor scent or the like "Adipose" redirects here For the Doctor Who monster see " Partners in Crime " Diuretics can thicken the blood, cause cramping, kidney and liver damage.

Stimulants

Stimulants such as ephedrine (now illegal in the United States due to an FDA ban) or synephrine work to increase the basal metabolic rate and reduce appetite. Stimulant drugs are Drugs that temporarily increase alertness and awareness Ephedrine (EPH is a Sympathomimetic Amine commonly used as a Stimulant, appetite suppressant concentration aid Decongestant, and to treat The United States of America —commonly referred to as the Synephrine (or oxedrine) is a Drug aimed at encouraging fat loss Basal metabolic rate ( BMR) is the amount of energy expended while at rest in a neutrally temperate environment in the post-absorptive state (meaning that the digestive system

Dangers of fasting

Main article: Fasting

Lengthy fasting can be dangerous due to the risk of malnutrition and should be carried out under medical supervision. Fasting is primarily the act of willingly abstaining from some or all Food, Drink, or both for a period of time Fasting is primarily the act of willingly abstaining from some or all Food, Drink, or both for a period of time Malnutrition is a general term for a medical condition caused by an improper or insufficient diet. During fasting, low-carbohydrate or very low calorie diets lack blood glucose, the preferred energy source of the brain, causing the body to metabolize sugars from protein, which over a prolonged fast can lead to muscle wasting. Very low calorie diet ( VLCD) is a diet with very or extremely low Calorie consumption per day The brain is the center of the Nervous system in animals All Vertebrates and the majority of Invertebrates have a brain

Side effects

Dieting, especially extreme food-intake reduction and rapid weight loss, can have the following side effects:

• Prolonged hunger
• Depression
• Reduced sex drive
• Fatigue
• Irritability
• Fainting
• Sinus problems (especially post-nasal drip)
• Muscle atrophy
• Rashes
• Acidosis
• Bloodshot eyes
• Gallbladder disease
• Seizures
• Malnutrition, possibly leading to death

See also

Body image Eating disorder Crash diet Dietitian Food faddism Healthy diet

List of diets National Weight Control Registry Nutritional rating systems Nutrition scale Underweight

References

External links

• Dieting at the Open Directory Project
• Video lectures at the Harvard School of public health
• A PBS Frontline interview with Prof. Walter Willett, Chair of Harvard's nutrition department

The Open Directory Project ( ODP) also known as dmoz (from directory

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