dieting dieting 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. 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. part of a series onhuman body weight general concepts obesity (epidemiology) overweight underweight body shape weight gain weight loss gestational weight gain diet (nutrition) weight management overnutrition childhood obesity (epidemiology) medical concepts adipose tissue classification of obesity genetics of obesity metabolic syndrome (epidemiology of metabolic syndrome) metabolically healthy obesity obesity paradox set 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obesity social stigma of obesity weight cutting weight class 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 led to his own dramatic weight loss. some guidelines recommend dieting to lose weight for people with weight-related health problems, but not for otherwise healthy people. one survey found that almost half of all american adults attempt to lose weight through dieting, including 66.7% of obese adults and 26.5% of normal weight or underweight adults. dieters who are overweight (but not obese), who are normal weight, or who are underweight may have an increased mortality rate as a result of dieting. history william banting, popularized one of the first weight loss diets in the 19th century. 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 who was obese. 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 with 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) rollo worked out a diet that had success for what is now called type 2 diabetes. the first popular diet was "banting", named after the english undertaker william banting. in 1863, he wrote a booklet called letter on corpulence, addressed to the public, which contained the particular plan for the diet he had successfully followed. his own diet was four meals per day, consisting of meat, greens, fruits, and dry wine. the emphasis was on avoiding sugar, sweet foods, starch, beer, milk and butter. banting's pamphlet was popular for years to come, and would be used as a model for modern diets. the pamphlet's popularity was such that the question "do you bant?" referred to his method, and eventually to dieting in general. his booklet remains in print as of 2007. the first weight-loss book to promote calorie counting, and the first weight-loss book to become a bestseller, was the 1918 diet and health: with key to the calories by american physician and columnist lulu hunt peters. it was estimated that over 1000 weight loss diets have been developed up to 2014. types main article: list of diets a restricted diet is most commonly pursued by those who want to lose weight. some people follow a diet to gain weight (such as people who are underweight or who are attempting to gain more muscle). diets can also be used to maintain a stable body weight or to improve health. low-fat main article: low-fat diet 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 this section is an excerpt from low-carbohydrate diet. an example of a low-carbohydrate dish, cooked kale and poached eggs low-carbohydrate diets restrict carbohydrate consumption relative to the average diet. foods high in carbohydrates (e.g., sugar, bread, pasta) are limited, and replaced with foods containing a higher percentage of fat and protein (e.g., meat, poultry, fish, shellfish, eggs, cheese, nuts, and seeds), as well as low carbohydrate foods (e.g. spinach, kale, chard, collards, and other fibrous vegetables). there is a lack of standardization of how much carbohydrate low-carbohydrate diets must have, and this has complicated research. one definition, from the american academy of family physicians, specifies low-carbohydrate diets as having less than 20% of calories from carbohydrates. there is no good evidence that low-carbohydrate dieting confers any particular health benefits apart from weight loss, where low-carbohydrate diets achieve outcomes similar to other diets, as weight loss is mainly determined by calorie restriction and adherence. an extreme form of low-carbohydrate diet called the ketogenic diet was first established as a medical diet for treating epilepsy. it became a popular fad diet for weight loss through celebrity endorsement, but there is no evidence of any distinctive benefit for this purpose and the diet carries a risk of adverse effects, with the british dietetic association naming it one of the "top five worst celeb diets to avoid" in 2018. low-calorie main article: calorie restriction low-calorie diets usually produce an energy deficit of 500–1,000 calories per day, which can result in a 0.5 to 1 kilogram (1.1 to 2.2 pounds) weight loss per week. 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. women doing low-calorie diets should have at least 1,000 calories per day and men should have approximately 1,200 calories per day. these caloric intake values vary depending on additional factors, such as age and weight. very low-calorie main article: very low calorie diet 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 starvation and produce an average loss of 1.5–2.5 kg (3.3–5.5 lb) per week. "2-4-6-8", a popular diet of this variety, follows a four-day cycle in which only 200 calories are consumed the first day, 400 the second day, 600 the third day, 800 the fourth day, and then totally fasting, after which the cycle repeats. there is some evidence that these diets results in considerable weight loss. these diets are not recommended for general use and should be reserved for the management of obesity as they are associated with adverse side effects such as loss of lean muscle mass, increased risks of gout, and electrolyte imbalances. people attempting these diets must be monitored closely by a physician to prevent complications. the concept of crash dieting is to drastically reduce calories, using a very-low-calorie diet. crash dieting can be highly dangerous because it can cause various kind of issues for the human body. crash dieting can produce weight loss but without professional supervision all along, the extreme reduction in calories and potential unbalance in the diet's composition can lead to detrimental effects, including sudden death. fasting main articles: fasting and intermittent fasting fasting is the act of intentional taking a long time interval between meals. lengthy fasting (multiple days in a week) might be dangerous due to the risk of malnutrition. during prolonged fasting or very low calorie diets the reduction of blood glucose, the preferred energy source of the 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 the issues of long fasting. intermittent fasting commonly takes the form of periodic fasting, alternate-day fasting, time-restricted feeding, and/or religious fasting. it can be a form of reduced-calorie dieting but pertains entirely to when the metabolism is activated during the day for digestion. the changes to eating habits on a regular basis do not have to be severe or absolutely restrictive to see benefits to cardiovascular health, such as improved glucose metabolism, reduced inflammation, and reduced blood pressure. studies have suggested that for people in intensive care, an intermittent fasting regimen might " energy supply to vital organs and tissues... powerfully activates cell-protective and cellular repair pathways, including autophagy, mitochondrial biogenesis and antioxidant defenses, which may promote resilience to cellular stress." the effects of decreased serum glucose and depleted hepatic glycogen causing the body to switch to ketogenic metabolism are similar to the effects of reduced carbohydrate-based diets. there is evidence demonstrating profound metabolic benefits of intermittent fasting in rodents. however, evidence is lacking or contradictory in humans and requires further investigation, especially over the long-term. some evidence suggests that intermittent restriction of caloric intake has no weight-loss advantages over continuous calorie restriction plans. for adults, fasting diets appear to be safe and tolerable, however there is a possibility that periods of fasting and hunger could lead to overeating and to weight regain after the fasting period. adverse effects of fasting are often moderate and include halitosis, fatigue, weakness, and headaches. fasting diets may be harmful to children and the elderly. exclusion diet this type of diet is based on the restriction of specific foods or food groups. examples include gluten-free, paleo, plant-based, and mediterranean diets. plant-based diets include vegetarian and vegan diets, and can range from the simple exclusion of meat products to diets that only include raw vegetables, fruits, nuts, seeds, legumes, and sprouted grains. exclusion of animal products can reduce the intake of certain nutrients, which might lead to nutritional deficiencies of protein, iron, zinc, calcium, and vitamins d and b12. therefore, long term implementation of a plant-based diet requires effective counseling and nutritional supplementation as necessary. plant-based diets are effective for short-term treatment of overweight and obesity, likely due to the high consumption of low energy density foods. however, evidence for long-term efficacy is limited. the paleo diet includes foods that were available to our hunter-gatherer ancestors including meat, nuts, eggs, some oils, fresh fruits, and vegetables. overall, it is high in protein and moderate in fats and carbohydrates. some limited evidence suggests various health benefits and effective weight loss with this diet. however, similar to the plant-based diet, the paleo diet has potential nutritional deficiency risks, specifically with vitamin d, calcium, and iodine. gluten-free diets are often used for weight loss but little has been studied about the efficacy of this diet and metabolic