R EVIEWNutraceutical meal replacements:more effective than all-food diets in thetreatment of obesityWendy M Miller†,Katherine E Nori Janosz,Kerstyn C Zalesin &Peter A McCullough†Authorfor correspondenceWilliam Beaumont Hospital,Weight Control Center,4949 Coolidge Highway,Royal Oak, MI48073–1026, USATel.: 1 248 655 5934;Fax: 1 248 655 5901;Email:[email protected]: diseasebiomarkers, glycemic index,meal replacement,nutraceutical, obesity, portioncontrol, satiety, weight loss,weight maintenancepart ofThe prevalence of obesity continues to increase in many developed countries throughoutthe world and is now referred to as a pandemic. Obesity is a chronic, relapsing disease,with neurochemical changes that influence energy balance, often rendering traditionaltreatment interventions ineffective at restoring normal body weight. Therefore, obesitytreatment interventions, including dietary strategies, are receiving increasing attention byinvestigators and clinicians. Hundreds of randomized, controlled trials examining variousfood diet interventions have found modest long-term weight loss. Meal replacements inthe form of drinks, bars and entrees work to replace food, restrict caloric intake and bluntthe rise of postprandial blood sugar, fatty acids and the resultant secretion of incretins,insulin and other factors. Thus, these agents have a significant neurohormonal impact thatenables weight reduction and have therefore been referred to as nutraceuticals – nutritionwith a pharmaceutical effect. There is accumulating evidence that meal-replacementdietary approaches are superior to all-food approaches for short- and long-term weightloss, as well as improvement of obesity comorbidities.According to the Centers for Disease Controland Prevention, the prevalence of obesity(defined as a BMI 30 kg/m2) continues toescalate in the USA and now comprises nearly athird of adults aged 20–74 years [1]. Unlikesome other chronic disease states, effectiveinterventions for obesity are lacking. Bariatricsurgery has shown the highest success rates forobesity management and Type 2 diabetes recovery to date, with an average weight loss of35–38% of initial total body weight and a72–83% recovery from diabetes at 1-year postroux-en-Y gastric bypass [2]. However, weightregain does occur and the data at 10 years postroux-en-Y gastric bypass show a mean weightloss of 25–28% and 36% recovery from diabetes [2]. Overall, outcomes with dietary obesityinterventions show a smaller percentage weightloss and are often associated with high attritionand low long-term maintenance [3].Although unproven, several factors arebelieved to be fueling the obesity epidemic,including increasing availability of high caloricdensity convenience foods and growingportion sizes. These unhealthy dietary changesin combination with increasingly sedentarylifestyles have likely tipped the energy balancefor most Americans (66%), and resulted inoverweight or obesity [1]. Several terms are usedto describe modern American cultureincluding ‘obesigenic society’, ‘toxic nutritional10.2217/14750708.4.5.623 2007 Future Medicine Ltd ISSN 1475-0708environment’ and ‘portion distortion.’ Regardless of which term is used, it is evident that amultifactorialpublichealthapproachpromoting and supporting healthy lifestyleswill be necessary to halt and reverse currentobesity trends.Although obesity prevention initiatives arethought to be the greatest hope for combatingthe obesity epidemic, we are currently faced withaddressing the millions of Americans sufferingfrom obesity and related comorbidities. Therefore, evaluation of available dietary interventions, as well as behavior modificationtechniques and exercise programs, is necessary todetermine optimal nonsurgical approaches.Weight-reduction diets range from fad diets, toevidence-based guidelines from medical ordietary associations, to medically supervised verylow calorie diets (VLCDs). Over the past decade,the nutraceutical meal replacement (MR)approach has received increasing recognition asan effective weight-management intervention.Meal replacements simplify portion controland calorie restriction and appear to provide arelatively high satiating effect per caloric density.Several randomized, controlled trials (RCTs)have demonstrated superior weight-management efficacy in comparison with all-food dietary approaches. This article will review thecurrent data on meal replacements as a tool forweight management in obesity.Therapy (2007) 4(5), 623–639623

REVIEW – Miller, Nori Janosz, Zalesin & McCulloughMeal replacement nutraceutical dietsA unified definition of what constitutes a MRdoes not currently exist. However, the term‘meal replacement’ is often used when referringto prepackaged, portion-controlled food products that are used to replace meals and/orsnacks. MRs are available in a variety of formsincluding liquids/shakes, powders (that are combined with liquids), soups, meal/snack bars andshelf-stable or frozen entrees. Various combinations of all three macronutrients – carbohydrate,protein, and fat – are present in most MRs(Table 1). Most are vitamin and mineral fortifiedand designed to provide a balanced, low-calorie,low-fat diet when combined with one or moremeals/snacks.VLCDs are diet plans that result in an intakeof 800 kcal/day or less. A VLCD is usually comprised solely of MRs, such as five 160 kcal MRshakes per day, and is also referred to as a ‘fullmeal replacement diet’. Medical monitoringshould always be part of a VLCD. More commonly, MRs are used by consumers to replaceone to two meals and/or snacks per day and areoften referred to as a ‘partial meal replacementdiet’. Two or more MR shakes (equating to 400–600 kcal total) plus fruit/vegetable snacksand one portion-controlled, low-fat meal resultsin a low calorie diet (LCD), equating to approximately 1100–1300 kcal/day. A LCD refers to adietary intake of 800–1500 kcal/day.Safety of meal replacement dietsWhile many clinical trials on MR diets havefound them safe and without adverse events,most of these trials involved overweight/obeseindividuals who were otherwise healthy (nocomorbidities). For those trials that studied MRdiets in diabetic subjects, the subjects withdiabetes were also otherwise relatively healthy[4,5]. Use of insulin and diabetic complicationswere exclusion criteria. Additionally, most trialgroups consisted of overweight or mildly obesesubjects, with mean BMIs of approximately30 kg/m2, rather than moderate to severely obeseindividuals with BMIs of 35 or greater and40 kg/m2, respectively.Evidence supports that use of a LCD of MRsplus food (a partial meal replacement diet)equating to approximately 1200 kcal/day orgreater, is generally safe for healthy individualswith no major medical illnesses. However,VLCDs or LCDs in patients with certainmedical problems can pose risk and medicalmonitoring is indicated. Chronic kidney disease,624Therapy (2007) 4(5)long QT syndrome, cardiac ischemia andcongestive heart failure are conditions that mayincrease risk with an MR diet. As most MR dietsare relatively low in sodium and carbohydratecontent, diuresis can occur. This can lead to electrolyte abnormalities and dehydration, particularly in those taking diuretics, which canexacerbate chronic kidney disease and cardiacischemia and can potentially provoke torsades depointes for those with long QT syndrome.Among those on antidiabetic agents, there is arisk of significant hypoglycemia upon starting aMR diet. Therefore, certain medications mayneed adjustment or discontinuation during aVLCD/LCD with MRs, including diuretics,insulin, sulfonylureas and meglitinides. Additionally, some medications may need more frequent monitoring, such as warfarin, digoxin,phenytoin and carbamazepine.Both obesity and weight loss increase risk ofgallstone development. Studies have found varying degrees of gallstone development duringweight loss, ranging from 10–12% after8–16 weeks of a LCD, 28% after 16 weeks on aVLCD and 30% within 12–18 months after gastric bypass surgery [6,7]. Ursodeoxycholic acid, abile salt that reduces cholesterol secretion intobile and improves biliary cholesterol solubility,has been shown to reduce risk of gallstone development during weight loss. A dose of600 mg/day was associated with a 3% risk ofgallstone development, compared with a 28%risk with placebo, during a 16-week trial of 1004morbidly obese (mean BMI 44 kg/m2) patientson a VLCD [7].Proposed mechanisms ofmeal replacementsThe effectiveness of a MR dietary approach islikely to be related to several factors, includingportion control, satiety and convenience.Portion controlMarked increases in portion sizes and energyintake among Americans, both inside and outside the household, have been documented.Nielsen and Popkin examined change in portionsizes from 1977–1996 with three nationally representativesurveysofmorethan63,000 Americans [8]. They found increases inportion sizes for a variety of foods includingsnacks, desserts, soft drinks, fruit drinks, frenchfries and hamburgers. Portion size changesequated to calorie increases of 49–133 kcal peritem for commonly consumed items.future science group

future science group160Scan Diet217211322202562425405328534755505913515373% 8353542322118% 2% kcal*www.futuremedicine.com2331111129111198based on RDAs of: sodium-2400 mg, potassium-3500 mg, calcium-1000 mg (for adults aged 20–50 years) [60].540652702602802202702602202009% 20517518131415171717% 4020402825256040505040% 12113211824Sugar(g)05120545355Fiber(g)of phosphorus derived from nutrition label %RDA, assuming RDA for phosphorus of 700 mg.Meal replacements: Slim-Fast (Slim-Fast Foods Company, West Palm Beach, FL, USA), Optifast (Novartis Nutrition Corporation, MN, USA), Health One (Health and Nutrition Technology, Carmel, CA, USA),HMR (Health Management Resources Corp., Boston, MA, USA), Procal (R-Kane Products, Inc., Pennsauken, NJ, USA), Scan Diet Shakes (Nutri Pharma, ASA; Oslo, Norway).n/a: Not available; RDA: Recommended daily allowance.‡mg†%RDA*Percentage of kilocalories based on product nutrition label calories and macronutrient g.100Procal160Optifast Readyto Drink160170Slim-Fast withSoy Protein110190Slim-Fast LowCarbHMR 800190Slim-Fast HighProteinHMR 70 h OnekcalMealreplacementTable 1. Macronutrient composition of common liquid meal replacements.Nutraceutical meal replacements – REVIEW625

REVIEW – Miller, Nori Janosz, Zalesin & McCulloughAnother study by Nielsen and Popkin examining beverage intake in more than 73,000Americans between 1977 and 2001 found anincrease in energy intake from sweetened beverages of 135% and a reduction of energy intakefrom milk of 38%, resulting in a 278 total calorie increase per person per day [9]. Theseincreases were associated with consuming largerportions as well as more servings per day ofsweetened beverages.Evidence suggests that the larger the portionsize, the larger the energy intake. Rolls and colleagues found that subjects consumed 30% moreenergy when offered the largest portion thanwhen offered the smallest portion [10]. Theresponse to the variations in portion size was notinfluenced by who determined the amount offood on the plate (subject vs investigator) or bysubject characteristics such as sex, BMI, or scoresfor dietary restraint or disinhibition. Likewise,Diliberti and colleagues found that when largerportion sizes are served at restaurants, more foodis eaten [11]. Hence, it is easy to see how growingportion sizes in America have resulted inincreased calorie consumption. Since anadditional 100 kcal/day can lead to a weight gainof 10 pounds over 1 year, inappropriate portionsize is likely to be a significant factor inpromoting obesity.As per the American Heart Association 2004Scientific Statement on obesity, portion controlis an important aspect of reducing energy intake[12]. Providing prepackaged prepared meals,either as frozen entrees of mixed foods or liquid-formula MRs, improves portion controland can enhance weight loss. MRs simplify portion control during weight loss by eliminatingthe need to measure or weigh food, or interpretfood labels. However, education on appropriateportion sizes and self-monitoring of energyintake is crucial for long-term maintenance ofweight loss.SatietyInvestigators have examined appetite and satietyin relation to food macronutrient composition.Foods with high satiation per caloric densitycould presumably aid in limiting overall energyintake. Among the macronutrients of fat, carbohydrate and protein, fat was previously considered to have the strongest effect on satiety. Fatclears more slowly from the stomach so gastrictransit time is prolonged with fat intake as compared with other macronutrients. More recentinvestigation, however, provides compelling626Therapy (2007) 4(5)evidence that fat is not the most satiatingmacronutrient. In fact, fat is likely to be theleast satiating macronutrient [13]. Instead, protein appears to provide the highest satiety [14,15].Studies examining both ratings of hunger following a protein preload as well as measurementof food intake have concluded that protein hasthe highest satiety.Studies examining carbohydrates and satietyoften reference glycemic index as a major stimulus for insulin release. Glycemic index is definedas the positive area under the glucose responsecurve after consumption of 50 g of available carbohydrate from a food test. Glycemic index values are expressed relative to the glucose responseobserved after the same amount of a referencefood, typically glucose or white bread [16].Although the evidence is inconclusive, someinvestigators have proposed that high glycemic