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Dieting

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Dieting is the practice of eating food in a regulated way to decrease, maintain, or increase body weight, or to prevent and treat diseases such as diabetes and obesity. Dieting to lose weight is recommended for people with weight-related health problems, but not otherwise healthy people. As weight loss depends on calorie intake, different kinds of calorie-reduced diets, such as those emphasising particular macronutrients (low-fat, low-carbohydrate, etc), have been shown to be no more effective than one another. As weight regain is common, diet success is best predicted by long-term adherence. Regardless, the outcome of a diet can vary widely depending on the individual. 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.

History

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According to Foxcroft, the word diet comes from the Greek diaita , which represents a notion of a whole way healthy lifestyle including both mental and physical health, rather than a narrow weight-loss regimen. One of the first dietitians was the English doctor George Cheyne. He himself was tremendously overweight and would constantly eat large quantities of rich food and drink. He began a meatless diet, taking only milk and vegetables, and soon regained his health. He began publicly recommending his diet for everyone suffering from obesity. In 1724, he wrote An Essay of Health and Long Life , in which he advises exercise and fresh air and avoiding luxury foods. The Scottish military surgeon, John Rollo, published Notes of a Diabetic Case in 1797. It described the benefits of a meat diet for those suffering from diabetes, basing this recommendation on Matthew Dobson's discovery of glycosuria in diabetes mellitus. By means of Dobson's testing procedure (for glucose in the urine...

Types

A restricted diet is more often pursued by those wanting to lose weight. Some people follow a diet to gain weight (usually in the form of muscle). Diets can also be used to maintain a stable body weight and improve health. Low-fat edit 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. A low-fat, plant-based diet has been found to improve control of weight, blood sugar levels, and cardiovascular health. Low-carbohydrate edit Low-carbohydrate diets are relatively high in protein and fats. Low-carbohydrate diets are sometimes ketogenic (i.e., they restrict carbohydrate intake sufficiently to cause ketosis). "The glycemic index (GI) factor is a...

Effectiveness

Several diets are effective for weight loss of obese individuals, with diet success most predicted by adherence and little effect resulting from the type or brand of diet. As weight maintenance depends on calorie intake, diets emphasising certain macronutrients (low-fat, low-carbohydrate, etc.) have been shown to be no more effective than one another and no 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). A meta-analysis of six randomized controlled trials found no difference between low-calorie, low-carbohydrate, and low-fat diets, with a 2–4 kilogram weight loss over 12–18 months in all studies. Extreme diets may, in some cases, lead to malnutrition. A major challenge regarding weight loss and dieting relates to compliance. While dieting can effectively promote weight loss in the short term, the intervention is hard to maintain over time and suppresses skeletal muscle therm...

Mechanism

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 glycogen (by glycogenolysis). Glycogen is a complex carbohydrate, 65% of which is stored in skeletal muscles and the remainder in the liver (totaling about 2,000 kcal in the whole body). It is created from the excess of ingested macronutrients, mainly carbohydrates. When glycogen is nearly depleted, the body begins lipolysis, the mobilization and catabolism of fat stores for energy. In this process fats, obtained from adipose tissue, or fat cells, are broken down into glycerol and 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. Set-Point Theory edit The Set-Point Theory, first introduced in 1953, postulated that each bo...

Methods

Meals timing edit Meals timing schedule is known to be an important factor of any diet. Recent evidence suggest that new scheduling strategies, such as intermittent fasting or skipping meals, and strategically placed snacks before meals, may be recommendable to reduce cardiovascular risks as part of a broader lifestyle and dietary change. Food diary edit 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 a person records their eating, they are more aware of what they consume and therefore eat fewer calories. Water edit A 2009 review found limited evidence suggesting that encouraging water consumption and substituting energy-free beverages for energy-containing beverages (i.e., reducing caloric intake) may facilitate weight management. A 2009 article found that drinking 500 ml of water prior to meals for a 12-week period...

Society

It is estimated that about 1 out of 3 Americans is dieting at any given time. 85% of dieters are women. Approximately sixty billion dollars are spent every year in the USA on diet products, including "diet foods," such as light sodas, gym memberships or specific regimes. 80% of dieters start by themselves, whereas 20% see a professional or join a paid program. The typical dieter attempts 4 tries per year. Weight loss groups edit Some weight loss groups aim to make money, others work as charities. The former include Weight Watchers and Peertrainer. The latter include Overeaters Anonymous, TOPS Club and groups run by local organizations. 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.

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