Nutraceutical Meal Replacements: More Effective Than All-Food Diets in the Treatment of Obesity
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REVIEW Nutraceutical meal replacements: more effective than all-food diets in the treatment of obesity Wendy M Miller†, The prevalence of obesity continues to increase in many developed countries throughout Katherine E Nori Janosz, the world and is now referred to as a pandemic. Obesity is a chronic, relapsing disease, Kerstyn C Zalesin & Peter A McCullough with neurochemical changes that influence energy balance, often rendering traditional treatment interventions ineffective at restoring normal body weight. Therefore, obesity †Author for correspondence William Beaumont Hospital, treatment interventions, including dietary strategies, are receiving increasing attention by Weight Control Center, investigators and clinicians. Hundreds of randomized, controlled trials examining various 4949 Coolidge Highway, food diet interventions have found modest long-term weight loss. Meal replacements in Royal Oak, MI 48073–1026, USA the form of drinks, bars and entrees work to replace food, restrict caloric intake and blunt Tel.: +1 248 655 5934; the rise of postprandial blood sugar, fatty acids and the resultant secretion of incretins, Fax: +1 248 655 5901; insulin and other factors. Thus, these agents have a significant neurohormonal impact that Email: [email protected] enables weight reduction and have therefore been referred to as nutraceuticals – nutrition with a pharmaceutical effect. There is accumulating evidence that meal-replacement dietary approaches are superior to all-food approaches for short- and long-term weight loss, as well as improvement of obesity comorbidities. According to the Centers for Disease Control environment’ and ‘portion distortion.’ Regard- and Prevention, the prevalence of obesity less of which term is used, it is evident that a (defined as a BMI ≥30 kg/m2) continues to multifactorial public health approach escalate in the USA and now comprises nearly a promoting and supporting healthy lifestyles third of adults aged 20–74 years [1]. Unlike will be necessary to halt and reverse current some other chronic disease states, effective obesity trends. interventions for obesity are lacking. Bariatric Although obesity prevention initiatives are surgery has shown the highest success rates for thought to be the greatest hope for combating obesity management and Type 2 diabetes recov- the obesity epidemic, we are currently faced with ery to date, with an average weight loss of addressing the millions of Americans suffering 35–38% of initial total body weight and a from obesity and related comorbidities. There- 72–83% recovery from diabetes at 1-year post- fore, evaluation of available dietary interven- roux-en-Y gastric bypass [2]. However, weight tions, as well as behavior modification regain does occur and the data at 10 years post- techniques and exercise programs, is necessary to roux-en-Y gastric bypass show a mean weight determine optimal nonsurgical approaches. loss of 25–28% and 36% recovery from diabe- Weight-reduction diets range from fad diets, to tes [2]. Overall, outcomes with dietary obesity evidence-based guidelines from medical or interventions show a smaller percentage weight dietary associations, to medically supervised very loss and are often associated with high attrition low calorie diets (VLCDs). Over the past decade, and low long-term maintenance [3]. the nutraceutical meal replacement (MR) Although unproven, several factors are approach has received increasing recognition as believed to be fueling the obesity epidemic, an effective weight-management intervention. including increasing availability of high caloric Meal replacements simplify portion control Keywords: disease density convenience foods and growing and calorie restriction and appear to provide a biomarkers, glycemic index, portion sizes. These unhealthy dietary changes relatively high satiating effect per caloric density. meal replacement, in combination with increasingly sedentary Several randomized, controlled trials (RCTs) nutraceutical, obesity, portion control, satiety, weight loss, lifestyles have likely tipped the energy balance have demonstrated superior weight-manage- weight maintenance for most Americans (66%), and resulted in ment efficacy in comparison with all-food die- overweight or obesity [1]. Several terms are used tary approaches. This article will review the part of to describe modern American culture current data on meal replacements as a tool for including ‘obesigenic society’, ‘toxic nutritional weight management in obesity. 10.2217/14750708.4.5.623 © 2007 Future Medicine Ltd ISSN 1475-0708 Therapy (2007) 4(5), 623–639 623 REVIEW – Miller, Nori Janosz, Zalesin & McCullough Meal replacement nutraceutical diets long QT syndrome, cardiac ischemia and A unified definition of what constitutes a MR congestive heart failure are conditions that may does not currently exist. However, the term increase risk with an MR diet. As most MR diets ‘meal replacement’ is often used when referring are relatively low in sodium and carbohydrate to prepackaged, portion-controlled food prod- content, diuresis can occur. This can lead to elec- ucts that are used to replace meals and/or trolyte abnormalities and dehydration, particu- snacks. MRs are available in a variety of forms larly in those taking diuretics, which can including liquids/shakes, powders (that are com- exacerbate chronic kidney disease and cardiac bined with liquids), soups, meal/snack bars and ischemia and can potentially provoke torsades de shelf-stable or frozen entrees. Various combina- pointes for those with long QT syndrome. tions of all three macronutrients – carbohydrate, Among those on antidiabetic agents, there is a protein, and fat – are present in most MRs risk of significant hypoglycemia upon starting a (Table 1). Most are vitamin and mineral fortified MR diet. Therefore, certain medications may and designed to provide a balanced, low-calorie, need adjustment or discontinuation during a low-fat diet when combined with one or more VLCD/LCD with MRs, including diuretics, meals/snacks. insulin, sulfonylureas and meglitinides. Addi- VLCDs are diet plans that result in an intake tionally, some medications may need more fre- of 800 kcal/day or less. A VLCD is usually com- quent monitoring, such as warfarin, digoxin, prised solely of MRs, such as five 160 kcal MR phenytoin and carbamazepine. shakes per day, and is also referred to as a ‘full Both obesity and weight loss increase risk of meal replacement diet’. Medical monitoring gallstone development. Studies have found vary- should always be part of a VLCD. More com- ing degrees of gallstone development during monly, MRs are used by consumers to replace weight loss, ranging from 10–12% after one to two meals and/or snacks per day and are 8–16 weeks of a LCD, 28% after 16 weeks on a often referred to as a ‘partial meal replacement VLCD and 30% within 12–18 months after gas- diet’. Two or more MR shakes (equating to tric bypass surgery [6,7]. Ursodeoxycholic acid, a ∼400–600 kcal total) plus fruit/vegetable snacks bile salt that reduces cholesterol secretion into and one portion-controlled, low-fat meal results bile and improves biliary cholesterol solubility, in a low calorie diet (LCD), equating to approxi- has been shown to reduce risk of gallstone devel- mately 1100–1300 kcal/day. A LCD refers to a opment during weight loss. A dose of dietary intake of 800–1500 kcal/day. 600 mg/day was associated with a 3% risk of gallstone development, compared with a 28% Safety of meal replacement diets risk with placebo, during a 16-week trial of 1004 While many clinical trials on MR diets have morbidly obese (mean BMI 44 kg/m2) patients found them safe and without adverse events, on a VLCD [7]. most of these trials involved overweight/obese individuals who were otherwise healthy (no Proposed mechanisms of comorbidities). For those trials that studied MR meal replacements diets in diabetic subjects, the subjects with The effectiveness of a MR dietary approach is diabetes were also otherwise relatively healthy likely to be related to several factors, including [4,5]. Use of insulin and diabetic complications portion control, satiety and convenience. were exclusion criteria. Additionally, most trial groups consisted of overweight or mildly obese Portion control subjects, with mean BMIs of approximately Marked increases in portion sizes and energy 30 kg/m2, rather than moderate to severely obese intake among Americans, both inside and out- individuals with BMIs of 35 or greater and side the household, have been documented. 40 kg/m2, respectively. Nielsen and Popkin examined change in portion Evidence supports that use of a LCD of MRs sizes from 1977–1996 with three nationally rep- plus food (a partial meal replacement diet) resentative surveys of more than equating to approximately 1200 kcal/day or 63,000 Americans [8]. They found increases in greater, is generally safe for healthy individuals portion sizes for a variety of foods including with no major medical illnesses. However, snacks, desserts, soft drinks, fruit drinks, french VLCDs or LCDs in patients with certain fries and hamburgers. Portion size changes medical problems can pose risk and medical equated to calorie increases of 49–133 kcal per monitoring is indicated. Chronic kidney disease, item for commonly consumed items. 624 Therapy (2007) 4(5) futurefuture sciencescience groupgroup Table 1. Macronutrient composition of common liquid meal replacements. future sciencegroupf u t u r e Meal kcal Carbohydrate Protein Fat Sodium Potassium Calcium Phosphorous