Dieting

Dieting is the practice of eating food in a regulated fashion to decrease, maintain, or increase body weight. Dieting is often used in combination with physical exercise to lose weight in those who are overweight or obese. ^[1] Some athletes, however, follow a diet to gain weight (usually in the form of muscle). Diets can also be used to maintain a stable body weight.

Diets to promote [3]

Long-term studies of dieting however indicate that the majority of individuals who dieted regain virtually all of the weight that was lost after dieting, regardless of whether they maintain their diet or exercise program.^[4]

The first popular diet was “Banting”, named after William Banting. In his 1863 pamphlet, Letter on Corpulence, Addressed to the Public, he outlined the details of a particular low-carbohydrate, low-calorie diet that had led to his own dramatic weight loss.^[7]

Contents 1 Types of diets 1.1 Low-fat diets 1.2 Low-carbohydrate diets 1.3 Low-calorie diets 1.4 Very low-calorie diets 1.5 Calorie Counting 1.6 Detox diets 2 Fat loss versus muscle loss 3 Energy obtained from food 4 Proper nutrition 5 How the body eliminates fat 6 Psychological aspects of weight loss 7 Weight loss groups 8 Food diary 9 Medications 9.1 Diuretics 9.2 Stimulants 10 Dangers of fasting 11 Side effects 12 Low carbohydrate versus low fat 13 Low glycemic index 14 See also 15 References 16 External links

[edit] Types of diets

[edit] Low-fat diets

Low-fat diets involve the reduction of the percentage of fat in one’s diet. Calorie consumption is reduced because less fat is consumed. Diets of this type include NCEP Step I and II. A meta-analysis of 16 trials of 2–12 months’ duration found that low-fat diets (without intentional restriction of caloric intake) resulted in average weight loss of 3.2 kg (7.1 lb) over habitual eating.^[2]

[edit] Low-carbohydrate diets

Low carbohydrate diets such as ketosis).

[edit] Low-calorie diets

Low-calorie diets usually produce an energy deficit of 500–1,000 calories per day, which can result in a 0.5 kilogram (1.1 lb) to 1 kilogram (2.2 lb) weight loss per week. Some of the most commonly used low-calorie diets include DASH diet and Weight Watchers. The National Institutes of Health reviewed 34 randomized controlled trials to determine the effectiveness of low-calorie diets. They found that these diets lowered total body mass by 8% in the short term, over 3–12 months.^[2]

[edit] Very low-calorie diets

Very low calorie diets provide 200–800 calories per day, maintaining protein intake but limiting calories from both fat and carbohydrates. They subject the body to [2]

[edit] Calorie Counting

Each pound of body fat is maintained by less than one extra calorie per hour. In general, obesity is not a condition maintained by overeating; obesity is a condition brought about and maintained by eating more calories than the body uses, consistently. As a practical example, eating twenty-five Burger King Whoppers rather than twenty-five McDonald Quarter Pounders can cause a weight gain of more than one and one-half pounds in that year. Twenty-five hamburgers represent 2% of yearly allotment of three meals a day. Making comparable choices at every meal for one year could yield an eighty-two-pound difference in body weight.^[8]

[edit] Detox diets

Detox diets claim to eliminate undesirable “toxins” from the human body rather than claiming to cause weight loss. Many of these use salt absorption).

[edit] Fat loss versus muscle loss

Weight loss typically involves the loss of fat, water and muscle. body fat percentage have been developed.

[9]

Excessive protein intake, though not connected to declined kidney functioning in healthy individuals,^[12] There is no conclusive evidence that moderately high protein diets in healthy individuals are dangerous; it has only been shown that these diets are dangerous in individuals already suffering from kidney and liver problems.

The Basal Metabolic Rate, which is the amount of calories the body expends at rest, meaning without performing any physical activity, is influenced by the person’s total weight and total amount of muscle. The more muscle, the more calories a person can burn naturally. When the amount of muscle is increased, then more calories can be ingested without gaining weight. Conversely, if the amount of fat is increased, increasing the number of calories ingested will only add weight.^[13]

Normally, when people lose weight, they lose a combination of fat and muscle. If the diet plan includes a daily caloric intake greater than the basal metabolic rate (BMR), the person will most likely lose fat. In contrast, if the person follows a diet that includes a lower caloric intake than the BMR, this person will lose fat but also a higher percentage of muscle.^{[metabolism because by losing muscle the BMR is affected.}

Maintaining muscle mass while losing fat is therefore a key factor to reach both the ideal weight and body composition.

[edit] Energy obtained from food

The energy intake from food is limited by the efficiency of hormone levels, and many more.

Chewing, especially in the elderly, has been shown to increase the intake of micronutrients. However, the effect of chewing on the intake of macronutrients, such as sugars, fats, and proteins has not been observed.^[14]

[edit] Proper nutrition

Dietary fiber also affects one’s health, although it’s not digested into the body.

The World Health Organization publish guidelines for dietary intakes of all known essential nutrients.

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 citation needed] Most people can obtain their nutritional needs from their diet. In any event, a multivitamin taken once a day will suffice for the majority of the population.

Weight loss diets that manipulate the proportion of macronutrients (low-fat, low-carbohydrate, etc.) have not been shown to be any more effective than diets that maintain a typical mix of foods with smaller portions and perhaps some substitutions (e.g. low-fat milk, or less salad dressing).^[15] Extreme diets may, in some cases, lead to malnutrition.

Besides the importance of eating a balanced diet that includes all the necessary nutrients, other factors also contribute to healthy nutrition. As well, drinking sufficient amounts of water is often claimed to help eliminate toxins and fat.^{[citation needed]} Heavily processed and fried foods as well as sweets, junk foods, and alcohol should also be avoided in a healthy diet.^[16]

Also a topic of great importance discussed among nutritionists as well as psychologists is the attitude to weight-loss and the consumption of food in general. Voicing ideas such as “it’s just one burger” during and after weight loss regimes is discouraged, and often is said on the part of an insecure individual who has reached the unfortunate conclusion that nothing can be done any longer and that any effort to do so is futile. The advice given is, avoid reaching such a conclusion, as not only does it change one’s perception of the effect of excessive amounts of food on the body, but also encourages a ‘lacklustre’ lifestyle and approach to life as a whole.

Nutritionists also agree on the importance of avoiding fats, especially saturated fats, to reduce weight and to be healthier. They also agree on the importance of reducing salt intake because commercial foods such as snacks, biscuits, and bread, among others, already contain salt, thus contributing to an excess of salt daily intake.^[17]

MyPyramid Food Guidance System is the result of extensive research performed by the United States Department of Agriculture to revise the original Food Guide Pyramid. It offers a wide array of personalized options to help individuals make healthy food choices. It also provides advice on physical activity.^[18]

[edit] How the body eliminates fat

All body processes require energy in order to function properly. When the body is expending more energy than it is consuming (e.g. when exercising), the body’s cells rely on internally stored energy sources, such as complex carbohydrates and fats, for energy. The first source to which the body turns is fatty acids, which can be used to generate energy. 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).

[edit] Psychological aspects of weight loss

Cognitive Behavior Therapy has been effective in producing long term weight loss.^[19]

[edit] Weight loss groups

Some weight loss groups aim to make money, others work as charities. The former include Overeaters Anonymous, also several groups run by local churches, hospitals, and like-minded individuals.

These organizations’ customs and practices differ widely. Some groups are modelled on twelve-step programs, while others are quite informal. 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.^[20]

[edit] Food diary

A 2008 study published in the American Journal of Preventive Medicine showed that dieters who kept a daily food diary (or diet journal), lost twice as much weight as those who did not keep a food log, suggesting that if you write your food down, you wouldn’t eat as many calories.^[21] Accordingly, diet journal software and websites have gained significant popularity, and help people track calorie consumption, calorie burning, weight loss goals, and nutritional balance.

[edit] Medications

Certain medications can be prescribed to assist in weight loss. The most recent prescription weight loss medication released is Acomplia (generic name Rimonabant), manufactured by Sanofi Aventis. Used to treat obesity in persons with a BMI (minerals, may not be effective for weight loss.

[edit] Diuretics

Diuretics induce weight loss through the excretion of water. Diuretics, which can be used in the forms of medications, supplements, or herbs, reduce overall body weight, but have no effect on an individual’s total body fat content. Diuretics can thicken the blood, cause cramping, kidney and liver damage. In a single report, the death of Jacqueline Henson was found to be related to swelling in her brain, which was associated with excessive water consumption over a short period of time, while she was on a special water diet.^[22]

[edit] Stimulants

citation needed]

[edit] Dangers of fasting

Lengthy brain, causes the body to deplete its glycogen stores. Once glycogen is depleted the body begins to fuel the brain using ketones, while also metabolizing body protein (including but not limited to skeletal muscle) to be used to synthesize sugars for use as energy by the rest of the body. Most experts believe that a prolonged fast can lead to muscle wasting although some dispute this. The use of short-term fasting, or various forms of intermittent fasting have been used as a form of dieting to circumvent this issue.

[edit] Side effects

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

• Subsequent weight re-gain
• Lowered metabolism, causing future attempts at weight loss to become more difficult, and making weight gain easier
• Muscle atrophy
• Risk of developing bulimia nervosa, even if initial intentions of dieting were health-wise
• Prolonged hunger
• Depression
• Reduced sex drive
• Fatigue
• Irritability
• Fainting
• post-nasal drip)
• Rashes
• Acidosis
• Bloodshot eyes
• Gallbladder disease
• Seizures
• death
• Constipation, due to lack of food-intake
• Dehydration, due to lack of fluid-intake

While there are studies that showed the health and medical benefits of weight loss, a study in 2005 of around 3000 Finns over an 18-year period showed that weight loss from dieting can result in increased mortality, while those who maintained their weight fared the best.^[6]

[edit] Low carbohydrate versus low fat

Many studies have focused on diets that reduce calories via a low-carbohydrate (Atkins diet, Scarsdale diet, Zone diet) diet versus a low-fat diet (LEARN diet, Ornish diet). The Nurses’ Health Study, an observational cohort study, found that low carbohydrate diets based on vegetable sources of fat and protein are associated with less coronary heart disease.^[25] The same study also found no correlation (with multivariate adjustment) between animal fat intake and coronary heart disease (table 4).

A [30]

The Women’s Health Initiative Randomized Controlled Dietary Modification Trial^[31] found that a diet of total fat to 20% of energy and increasing consumption of vegetables and fruit to at least 5 servings daily and grains to at least 6 servings daily resulted in:

• no reduction in cardiovascular disease^[32]
• no statistically significant reduction in invasive breast cancer^[33]
• no reductions in colorectal cancer^[34]

Additional recent randomized controlled trials have found that:

• A comparison of Atkins, Zone diet, Ornish diet, and LEARN diet in premenopausal women found the greatest benefit from the Atkins diet.^[35]

• The choice of diet for a specific person may be influenced by measuring the individual’s insulin secretion:

In [38]

The American Diabetes Association released for the first time a recommendation (in its January 2008 Clinical Practice Recommendations) for a low carbohydrate diet to reduce weight for those with or at risk of Type 2 diabetes.^[39]

[edit] Low glycemic index

“The [41]

The glycemic load is “the mathematical product of the glycemic index and the carbohydrate amount”.^[42]

In a randomized controlled trial that compared four diets that varied in carbohydrate amount and glycemic index found complicated results^[43]:

• Diet 1 and 2 were high carbohydrate (55% of total energy intake)
  • Diet 1 was high-glycemic index
  • Diet 2 was low-glycemic index
• Diet 3 and 4 were high protein (25% of total energy intake)
  • Diet 3 was high-glycemic index
  • Diet 4 was low-glycemic index

Diets 2 and 3 lost the most weight and fat mass; however, low density lipoprotein fell in Diet 2 and rose in Diet 3. Thus the authors concluded that the high-carbohydrate, low-glycemic index diet was the most favorable.

A meta-analysis by the Cochrane Collaboration concluded that low glycemic index or low glycemic load diets led to more weight loss and better lipid profiles. However, the Cochrane Collaboration grouped low glycemic index and low glycemic load diets together and did not try to separate the effects of the load versus the index.^[40]

[edit] See also

Wikiquote has a collection of quotations related to: Diet

[edit] References

[edit] External links

• Dieting at the Open Directory Project
• The food pyramid: Video lectures at the Harvard School of public health
• US News and World Report, Health: Eat Like Our Ancestors. An Interview with Harvard Psychology’s Deirdre Barrett 6/29/07
• A PBS Frontline interview with Prof. Walter Willett, Chair of Harvard’s nutrition department
• Weight Management
• “Not All Calories Are Created Equal, Author Says”. Excerpt from Good Calories, Bad Calories and NPR interview with Ronald Krauss (November 2, 2007).

Source: Wikipedia