V ery-low-calorie (VLC) diets are administered by physicians who use them to treat a variety of conditions, including obesity, diabetes, cardiovascular disease, and hormonal disorders. These diets have undergone many changes since they were first developed and are the topic of ongoing debates amongst obesity researchers. Questions about safety and efficacy permeate these debates, but at a time when doctors and patients are looking for radical remedies to the growing problem of obesity, VLC diets are a promising if uncertain method of inducing weight loss. Low calorie (LC) diets and VLC diets are often conflated in popular discourse even though there are important distinctions between them. In addition, it is tempting to equate VLC dieting with eating disorders like anorexia and compulsive avoidance of foods. Confusion about VLC dieting and disordered eating is understandable because VLC dieters and pathological eaters may display similar behaviors. Nevertheless, VLC diets are still an important medical tool in fighting obesity.
It is important to distinguish VLC diets from the more familiar LC diets. Definitions of VLC and LC diets have changed over time with the introduction of international CODEX standardization and FDA and EU legislation limiting food restriction (Howard 1989: 6-7; Saris 2001: 295S; Scientific Cooperation 2002). A LC diet generally provides between 800 and 1,200 calories per day, but some LC diets may contain as many as 1,500 calories per day (Saris 2001: 295S; Wadden and Berkowitz 2002: 534). Some of the most popular commercial diet programs are LC diets, including Jenny Craig and LA Weight Loss among others; these diets are available to all consumers and are not physician supervised (Scientific Cooperation 2002: 10; Tsai and Wadden 2005: 58). VLC diets, on the other hand, consist of between 400/450 and 800 calories per day, although some may provide up to 1,200 calories per day (CODEX 1995: 1; Saris 2001; Scientific Cooperation 2002: 10). In some cases, a VLC diet may also be defined as any diet that provides less than 50 percent of an individual's predicted energy requirements (Wadden and Berkowitz 2002: 534). VLC diets are generally carried out under the supervision of a physician and are not recommended for self-treatment of overweight or obesity. Widely used VLC diets include Medifast, OPTIFAST, Heath Management Resources (HMR), and the Cambridge Diet (Scientific Cooperation 2002: 35-7; Tsai and Wadden 2005: 59).
VLC diets rely on calorie-counting to create a negative energy balance in the patient, who will then lose weight. Calorie-counting was first introduced in 1918, and VLC diets were originally developed in the late 1920s and early 1930s by the Pittsburgh group of physicians (Howard 1981). The first research published on VLC diets appeared in 1929 as a new method for treating obesity (Evans and Strang 1995; Saris 2001: 295S). This original VLC diet prescribed a diet of 6 to 8 calories per kilogram of body weight instead of the usual 14 to 15 calories per kilogram (Howard 1989: 1; Saris 2001: 295S), which created a caloric deficit as great as 1,720 calories in some cases and resulted in dramatically greater weight loss in obese patients (Evans and Strang 1995: 211-12). While caloric reduction was severe, the diet provided approximately 400 calories and was not a pure fast (Saris 2001: 295S).
In 1959, however, W.L. Bloom reintroduced therapeutic fasting as a method for treating obesity. While patients using the fasting treatment lost weight, they also lost valuable protein and nitrogen; therefore, "protein sparing," which involved supplementing the fast with lean meat and egg albumin, was introduced in the late 1960s (Howard 1989: 3; Vertes 1984: 56). While an improvement over zero-calorie programs, these supplemented diets were often deficient in carbohydrates, which led to ketosis and loss of essential minerals. The development of modern VLC diet formulas sought to address these deficiencies, and canned liquid drinks were introduced in i962. This MetroCal diet plan provided approximately 900 calories and was the first "nutritionally complete food for the treatment of obesity" (Howard 1989: 3-4). All of these early modern VLC diets worked by inducing anorexia (absence of hunger) if the patient adhered to them strictly for three days (Howard 1989: 4).
In the 1970s, VLC diet products were sold in the form of liquid-protein meal replacements. Unfortunately, because these new products used hydrolyzed collagen (a low-value protein) as the only protein source and did not include adequate amounts of vitamins, minerals, and electrolytes, their use was associated with several sudden deaths between 1976 and 1978 (Howard 1989: 4-5; Saris 2001: 295S-96S; Vertes 1984: 57). Subsequent studies have suggested that these deaths may have resulted from cardiac arrhythmias and/or mineral malnutrition; however, there is no conclusive evidence that VLC diet use causes sudden death (Howard 1989: 4; Saris 2001: 296S; Vertes 1984: 57). Still, the medical community and the public became wary of using VLC diets to treat obesity.
As a result, doctors, scientists, and other health and governmental officials have worked to develop guidelines for ensuring the safety of dieters. In 1987, the U.K. Department of Health and Social Security COMA report recommended that VLC diets should be used only after the failure of conventional food diets and should provide no less than 400-500 calories per day (Howard 1989: 6-7). In 1995, CODEX, the body responsible for recommending international food standards to the UN and World Health Organization (WHO), also suggested that VLC diets provide between 450 and 800 calories per day (CODEX 1995: 1).
In addition, the U.S. Dietary Guidelines Advisory Committee has published recommended energy intakes (number of calories) for various age and sex groups. In order to lose weight, the committee recommends cutting no more than 300 to 500 calories from one's daily intake (Department of Health and Human Services 2005). Most dietary guidelines for losing weight recommend that all dieters should consume no less than 1,200 calories per day for safe and lasting weight loss. According to the
National Library of Medicine's dietary recommendations, "diets that are excessively low in calories are considered dangerous and do not result in healthful weight loss" (U.S. National Library of Medicine). Moreover, the National Institutes of Health Institute of Diabetes, Digestive, and Kidney Diseases (NIDDK) warns that, "diets that provide less than 800 calories per day also could result in heart rhythm abnormalities, which can be fatal" (NIDDK 2006).
Nevertheless, VLC diets continue to prescribe much larger caloric deficits, and most scientists agree that VLC diet products are safe when they are closely monitored by a doctor, contain adequate protein and carbohydrates, and are supplemented with essential vitamins and micronutrients (Vertes 1984: 57-8; Zahouani et al. 2003: S149). In addition, the benefits of VLC diets may outweigh their risks in cases of morbid obesity. There is evidence to suggest that VLC diet programs can result in dramatic weight loss and improved overall health (Kanders et al. 1989; Stordy 1989). In fact, studies of HMR and OPTIFAST suggest that patients on a comprehensive program can expect to lose approximately i5-25 percent of their initial weight during three to six months of treatment and may maintain a loss of 8-9 percent after one year following the initial treatment. These numbers decrease as time passes, but even after four years, patients treated with VLC diets may still show lasting results of their weight loss (Tsai and Wadden 2005: 62-3).
VLC diets have also been proven to be an effective method in jump-starting patients on conventional weight-loss treatments (Quaade and Astrup 1989). In addition, VLC diets have been shown to reduce cravings for unhealthy foods (Harvey et al. 1993; Martin et al. 2006) and improve obesity-related conditions, such as non-insulin-dependent diabetes (Capstick et al. 1997), sleep apnea and hypertension (Kansanen et al. 1998), cardiovascular disease (Ramhamadany et al. 1989), and hormonal and metabolic disorders, such as polycystic ovarian syndrome and related hirsutism (Okajima et al. 1994).
However, concerns still exist about the effectiveness of VLC diets and the ability of patients to "keep the weight off" (Howard 1981). First of all, researchers disagree on the efficacy of VLC diets, and some argue that weight loss is no greater with VLC diets than with the less restrictive LC diets (Garrow 1989: 147; Saris 2001: 297S-98S). In addition, studies show that almost all patients treated with VLC diets will regain much of the weight that they initially lose (Paisey et al. 2002: 125; Vertes 1984: 57;
Wadden et al. 1989; Wadden and Berkowitz 2002: 536). For example, a 1989 study of VLC diet, behavior therapy, and their combination to treat obesity showed that after five years, 55 percent of subjects gained back most or all of the weight that they lost during treatment (Wadden et al. 1989).
Regaining lost weight is, in part, attributed to the fact that VLC diets are extremely restrictive, and many patients resume their pretreatment eating habits and, therefore, return to their previous weight. In one study, researchers found that only about one-fifth of the people who attempted the Cambridge Diet succeeded in complying with it fully for two weeks (Heller and Edelmann 1991). In another study, forty-one of seventy-six patients reported a fasting lapse within the first eleven weeks of a VLC diet program (Mooney et al. 1992: 321). While these numbers are not surprising considering the recidivism rates associated with all forms of dieting and weight loss, the inability of patients to sustain VLC dieting practices does seem to limit their effectiveness for long-term weight loss. In addition, it is possible that the long-term failure of VLC diets may result, in part, from depressed resting metabolic rates that have been observed in patients on these modified fasts (Kanders et al. 1989: 133; Vansant et al. 1989). There are clearly substantial problems that VLC dieters must confront in their efforts to lose weight.
VLC diets have changed repeatedly since their development in the late 1920s, yet they remain a hotly debated topic amongst obesity researchers. Concerns about safety have decreased since the 1980s because commercial formulas have been nutritionally improved and regulated, yet uncertainties about long- and short-term efficacy remain. The use of near-starvation practices in medically supervised dieting is also interesting in a culture that is arguably obsessed with pathological eating disorders. While an obese man may consume a 450-calorie VLCD at the suggestion of his physician, a young girl who follows similar eating habits on her own may easily be diagnosed as suffering from anorexia. Determining the appropriate amount of calories for safe and healthy weight loss or weight gain is important, but, as the history of VLC diets suggest, this determination is mutable and ultimately contingent upon current medical fashion.
SLG/C. Melissa Anderson
See also Anorexia; Calorie; Craig; Linn; Metabolism; Obsessive Compulsive Disorders; Peters
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