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Dieting is the practice or habit of eating (and drinking) in a regulated fashion with the aim of losing (or, sometimes, gaining) weight, or
in some cases to regulate the amounts of certain nutrients entering the body.
Dieting for weight loss is ancient in origins. Throughout the 17th and 18th centuries, physicians and patients regulated their
food carefully to prevent disease. The scientific classification of foods were broken into proteins, carbohydrates, starches and lipids. A practice throughout the 19th century, doctors and
scientists began experimenting with targeted diets. One of the first people known to have successfully lost weight by dieting, by
targeting carbohydrates, (see the Atkins diet for the contemporary popularity
of this method) was William Banting in 1863.
Measuring body weight on a scale
Medical diets
Medical conditions often require the use of a special diet
that either contains or lacks certain chemicals. A person who has diabetes is often
on a diet designed to carefully regulate their blood sugar level. Sufferers
of celiac disease must follow a gluten-free diet, the lactose-intolerant omit
milk and dairy products, while people with kidney disease must follow a strict
low-sodium diet to ease the strain on their kidneys.
Religious diets
Certain religions, including Judaism and Islam, also impose strict restrictions on diet and food preparation, but these are not usually thought of as
"dieting". Neither are the various forms of vegetarianism, which may be
adopted for religious, spiritual or ethical reasons, or due to other food choices not being unavailable.
Weight loss
Most typically "dieting" means eating in a carefully planned way in an attempt to reduce excess body fat and decrease bodily
measurements, such as clothing size. In this sense, there are a number of so-called
diets that can be used as part of a regimen of dieting. Anorexia
nervosa and bulimia, which are psychological and neurological
disorders that cause victims to endanger their lives with calorie restriction, must
not be confused with dieting. There are many organizations, such as Weight Watchers and Jenny Craig, that support weight loss efforts on a for-profit basis, by providing prepared food or special
menus and individual or group counselling sessions, as well as teaching exercise routines, with the aim of improving clients'
lifestyles and enabling them to maintain successful weight loss. It is highly questionable as to the overall long-term success of
these diets, however, as many people gain the weight they've lost back - and then some. This is due partially to a dependence
upon the program and partially to the body's own famine response.
Fad diets
There are as many different recommendations for supposedly successful diets as there are people trying to lose weight. What
works for one person will not necessarily work for another due to metabolic differences and lifestyle factors. Many 'fad' diets
become popular for a short space of time - the grapefruit diet as well as
Atkins are good examples of this. On the grapefruit diet, the consumption of grapefruit
with each meal was said to increase the metabolic rate, burning fat and enabling rapid weight loss. Like most fad diets, the
grapefruit diet was eventually found to be entirely ineffective, and it was replaced by the next fad - Atkins. Atkins encouraged controlling carbohydrate
intake, and encouraged meats and green vegetables. This induces ketosis, causing effective weight loss for many people.
Low-fat diets were popular during the 80s and 90s, encouraging people to eat foods low in fat (or without fat altogether) and
instead eat foods high in carbohydrates. The diet worked on the principle that of the three main macro-nutrients (fat,
carbohydrates and protein), only fat was the one which would cause weight-gain. This failed as people ended up eating excessive
amounts of low-fat foods rich in carbohydrates, and so did not lose much weight, or even gained it due to the energy from the
carbohydrates.
Very Low Calorie Diets
The Very Low Calorie Diet, or VLCD, is a special diet to be undertaken with medical supervision. It offers rapid fat loss over
a short timeframe, but can be dangerous for some people. It consists of the consumption of a special powder mixed in with
200-300ml of water to be taken three times a day. The drink, similar to a milkshake, provides approximately 1914Kj (456 Cal) of
energy per day when consumed at breakfast, lunch and dinner. It contains all necessary vitamins and minerals, although there is a
risk of overdosing on Selenium if a person consumes more than they should (more
than three times per day). VLCD's should only be used for dieting when a person's Body mass index exceeds 30. In addition, at least 2 litres of water must be consumed per day and a person
should consider using fibre supplements regularly. Without this, the person risks severe
constipation.
VLCD's can be very successful but only when used over a 6-12 week period. Because the body is essentially starving, it is burning
up its fat stores and lowering its metabolic rate. As soon as the diet ceases and normal food is consumed again, there is an
immediate increase in weight. Short-term use of VLCDs (1-4 weeks) will have little, if any, benefit for the dieter as the
increase in weight will negate the weight lost in the first place. Once the full course of the diet is finished, it is up to the
successful dieter to maintain their current weight via exercise and sensible eating, otherwise they will put on weight again.
VLCD's put a great deal of strain on a person's body, and should only be undertaken with medical consultation.
Dieting principles
Successful weight loss diet is all about energy in versus energy out. If a person takes in fewer calories than he or she expends over a period of time, the person may burn fat and
subsequently lose weight. To lose a pound of fat, one must create a caloric deficit of approximately 3,500 calories (37,600 kJ
per kilogram of fat); therefore, if a person creates a deficit of 500 calories per day, the person will lose approximately 1
pound of fat per week (5,400 kJ per day to lose a kilo a week).
However, it is to be noted that weight loss from restrictive eating and exercise can also be muscle weight loss, too. The
muscle-loss during weight-loss can be restricted through regular weight-lifting and a high protein intake. It is said that 0.8-1.0g of protein per pound of bodyweight (0.36-0.45g per kg) per day is
sufficient. A ketogenic diet is often
very effective in lowering body-fat levels whilst maintaining or even increasing muscle mass.
Dieting to lose weight does just that -- you lose weight, water, some fat and muscles. Since muscles are denser, you lose a
lot of weight, but little in size. Fat is bulkier, so a three pound fat loss can cause a size loss. Anyone can lose weight by
famining. Famines happened to those in concentration camps and when they were examined by doctors, they discovered they were
mostly fat, what little weight they had, and practically no muscle.
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. This can be attempted by focusing on foods that are filling, through the use of certain appetite suppressing drugs,
or through activities such as mild exercise, that affect appetite. Other techniques address habitual or emotional eating.
Affecting the "energy out" component is the focus of fitness and exercise programs. These might also be included in a comprehensive "diet".
Hazards
Dieting has hazards that are rarely pointed out. Yo-yo dieting is particularly dangerous and ineffective, because it decreases the metabolism, leading
to an immediate weight gain once the caloric restrictions are eased. Some dieters resort to over the counter (OTC) and/or
prescribed medications to improve their results, but many of these have been proven to be extremely hazardous to the health (and
consequently withdrawn from sale) so consumers need to be wary.
The only "safe" method of weight loss is to eat a sensible healthy diet with a moderately decreased caloric intake from your
norm, and to increase exercise gradually until weight loss results. It should be noted that people may follow these guidelines
and not actually lose weight, but may see health improvements.
Related topics
List of diets, Food
faddism, Body image, Appetite suppressant
External links
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