Dieting
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Dieting is the practice of
The first popular diet was "Banting", named after
Some guidelines recommend dieting to lose weight for people with weight-related health problems, but not for otherwise healthy people.[9][10] 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.[11] 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.[9]
History
The word diet comes from the Greek δίαιτα (diaita), which represents a notion of a whole way healthy lifestyle including both mental and physical health, rather than a narrow weight-loss regimen.[12][13]
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.[14]
The Scottish military surgeon,
The first popular diet was "Banting", named after the English
The first weight-loss book to promote calorie counting, and the first weight-loss book to become a bestseller, was the 1918
It was estimated that over 1000 weight-loss diets have been developed up to 2014.[21]
Types
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.[22]
Low-fat
Low-fat diets involve the reduction of the percentage of fat in one's diet. Calorie consumption is reduced because less fat is consumed.[23] 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.[1]
A low-fat, plant-based diet has been found to improve control of weight,
Low-carbohydrate
There is a lack of standardization of how much carbohydrate low-carbohydrate diets must have, and this has complicated research.[25] One definition, from the American Academy of Family Physicians, specifies low-carbohydrate diets as having less than 20% of calories from carbohydrates.[26]
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.[27]
One form of low-carbohydrate diet called theLow-calorie
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.[30] 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.[1] 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.[1]
Very low-calorie
Very low calorie diets provide 200–800 calories per day, maintaining protein intake but limiting calories from both fat and carbohydrates.
The concept of crash dieting is to drastically reduce calories, using a very-low-calorie diet.[32][33][34][35] 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.[36]
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.[37] 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.[22] 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.[22] Most experts believe that a prolonged fast can lead to muscle wasting,[38] although some[who?] dispute this.[citation needed] 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.[39]
Intermittent fasting commonly takes the form of periodic fasting, alternate-day fasting, time-restricted feeding, and/or religious fasting.
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.[43] 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.[43] 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.[22] However, evidence for long-term efficacy is limited.[22]
The Paleo diet includes foods that were available to our hunter-gatherer ancestors[44] including meat, nuts, eggs, some oils, fresh fruits, and vegetables.[22] 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.[22]
Gluten-free diets are often used for weight loss but little has been studied about the efficacy of this diet and metabolic mechanism for its effectiveness is unclear.[22]
The Mediterranean diet is characterized by high consumption of vegetables, fruits, legumes, whole-grain cereals, seafood, olive oil, and nuts. Red meat, dairy and alcohol are only recommended in moderation. Studies show that the Mediterranean diet is associated with short term as well as long term weight loss in addition to health and metabolic benefits.[22]
Detox
Detox diets are promoted with unsubstantiated claims that they can eliminate "toxins" from the human body. Many of these diets use herbs or celery and other juicy low-calorie vegetables. Detox diets can include fasting or exclusion (as in juice fasting). Detox diets tend to result in short-term weight loss (because of calorie restriction), followed by weight gain.[45]
Environmentally sustainable
Another kind of diet focuses not on the dieter's health effects, but on its environment. The One Blue Dot plan of the BDA[46] offers recommendations towards reducing diets' environmental impacts, by:
- Reducing meat to 70g per person per day.
- Prioritising plant proteins.
- Promoting fish from sustainable sources.
- Moderate dairy consumption.
- Focusing on wholegrain starchy foods.
- Promoting seasonal locally sourced fruits and vegetables.
- Reducing high fat, sugar and salty foods overconsumption.
- Promoting tap water and unsweetened tea/coffee as the de facto choice for healthy hydration.
- Reducing food waste.
Effectiveness
Several diets are effective for short-term
A major challenge regarding weight loss and dieting relates to compliance.[2] While dieting can effectively promote weight loss in the short term, the intervention is hard to maintain over time and suppresses skeletal muscle thermogenesis. Suppressed thermogenesis accelerates weight regain once the diet stops, unless that phase is accompanied by a well-timed exercise intervention, as described by the Summermatter cycle.[52] Most diet studies do not assess long-term weight loss.[2]
Some studies have found that, on average, short-term dieting results in a "meaningful" long-term weight-loss, although limited because of gradual 1 to 2 kg/year weight regain.[10][2][6] Because people who do not participate in weight-loss programs also tend to gain weight over time, and baseline data from such "untreated" participants are typically not included in diet studies, it is possible that diets do result in lower weights in the long-term relative to people who do not diet.[2] Others have suggested that dieting is ineffective as a long-term intervention.[7] For each individual, the results will be different, with some even regaining more weight than they lost, while a few others achieve a tremendous loss, so that the "average weight loss" of a diet is not indicative of the results other dieters may achieve.[2][7] A 2001 meta-analysis of 29 American studies found that participants of structured weight-loss programs maintained an average of 23% (3 kg) of their initial weight loss after five years, representing a sustained 3.2% reduction in body mass.[6] Unfortunately, patients are generally unhappy with weight loss of <10%,[2] and reductions even as high as 10% are insufficient for changing someone with an "obese" BMI to a "normal weight" BMI.
Partly because diets do not reliably produce long-term positive health outcomes, some argue against using weight loss as a goal, preferring other measures of health such as improvements in cardiovascular biomarkers,[53][54] sometimes called a Health at Every Size (HAES) approach[55] or a "weight neutral" approach.[56]
Long term losses from dieting are best maintained with continuing professional support, long term increases in physical activity, the use of anti-obesity medications, continued use of meal replacements, and additional periods of dieting to undo weight regain.[2] The most effective approach to weight loss is an in-person, high-intensity, comprehensive lifestyle intervention: overweight or obese adults should maintain regular (at least monthly) contact with a trained interventionalist who can help them engage in exercise, monitor their body weight, and reduce their calorie consumption.[10] Even with high-intensity, comprehensive lifestyle interventions (consisting of diet, physical exercise, and bimonthly or even more frequent contact with trained interventionists), gradual weight regain of 1–2 kg/year still occurs.[10] For patients at high medical risk, bariatric surgery or medications may be warranted in addition to the lifestyle intervention, as dieting by itself may not lead to sustained weight loss.[10]
Many studies overestimate the benefits of calorie restriction because the studies confound exercise and diet (testing the effects of diet and exercise as a combined intervention, rather than the effects of diet alone).[57]
Adverse effects
Increased mortality rate
A number of studies have found that intentional weight loss is associated with an increase in mortality in people without weight-related health problems.[58][59][60][61] A 2009 meta-analysis of 26 studies found that "intentional weight loss had a small benefit for individuals classified as unhealthy (with obesity-related risk factors), especially unhealthy obese, but appeared to be associated with slightly increased mortality for healthy individuals, and for those who were overweight but not obese."[9]
Dietary supplements
Due to extreme or unbalanced diets, dietary supplements are sometimes taken in an attempt to replace missing vitamins or minerals. While some supplements could be helpful for people eating an unbalanced diet (if replacing essential nutrients, for example), overdosing on any dietary supplement can cause a range of side effects depending on the supplement and dose that is taken.[62] Supplements should not replace foods that are important to a healthy diet.[62]
Eating disorders
In an editorial for Psychological Medicine, George Hsu concludes that dieting is likely to lead to the development of an eating disorder in the presence of certain risk factors.[63] A 2006 study found that dieting and unhealthy weight-control behaviors were predictive of obesity and eating disorders five years later, with the authors recommending a "shift away from dieting and drastic weight-control measures toward the long-term implementation of healthful eating and physical activity".[64]
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
Set-Point Theory
The Set-Point Theory, first introduced in 1953, postulated that each body has a preprogrammed fixed weight, with regulatory mechanisms to compensate. This theory was quickly adopted and used to explain failures in developing effective and sustained weight loss procedures. A 2019 systematic review of multiple weight change procedures, including alternate day fasting and time-restricted feeding but also exercise and overeating, found systematic "energetic errors" for all these procedures. This shows that the body cannot precisely compensate for errors in energy/calorie intake, countering the Set-Point Theory and potentially explaining both weight loss and weight gain such as obesity. This review was conducted on short-term studies, therefore such a mechanism cannot be excluded in the long term, as evidence is currently lacking on this timeframe.[66]
Methods
Meals timing
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.[67]
Food diary
A 2008 study published in the
Water
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 resulted in increased long-term weight reduction. (References given in
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.[69][70] 80% of dieters start by themselves, whereas 20% see a professional or join a paid program. The typical dieter attempts 4 tries per year.[71]
Weight loss groups
Some weight loss groups aim to make money, others work as charities. The former include
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.[citation needed]
Attending group meetings for weight reduction programmes rather than receiving one-on-one support may increase the likelihood that obese people will lose weight. Those who participated in groups had more treatment time and were more likely to lose enough weight to improve their health. Study authors suggested that one explanation for the difference is that group participants spent more time with the clinician (or whoever delivered the programme) than those receiving one-on-one support.[72][73]
See also
- Body image
- Carbon footprint
- Dietary Guidelines for Americans
- Food faddism
- High residue diet
- Intuitive eating
- List of diets
- National Weight Control Registry
- Nutrigenomics
- Nutrition psychology
- Nutrition scale
- Nutritional rating systems
- Online weight loss plans
- Superfood
- Table of food nutrients
- Underweight
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Further reading
- American Dietetic Association (June 2003). "Position of the American Dietetic Association and Dietitians of Canada: Vegetarian diets". Journal of the American Dietetic Association. 103 (6): 748–765. PMID 12778049.
- Cheraskin E (1993). "The Breakfast/Lunch/Dinner Ritual". Journal of Orthomolecular Medicine. 8 (1).
- Dansinger ML, Gleason JL, Griffith JL, Li WJ, Selker HP, Schaefer EJ (12 November 2003). One Year Effectiveness of the Atkins, Ornish, Weight Watchers, and Zone Diets in Decreasing Body Weight and Heart Disease Risk. American Heart Association Scientific Sessions. Orlando, Florida.
- Schwartz, Hillel. Never Satisfied: A Cultural History of Diets, Fantasies, and Fat. New York: Free Press/Macmillan, 1986.