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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 & with neurochemical changes that influence energy balance, often rendering traditional
Peter A McCullough
† treatment interventions ineffective at restoring normal body weight. Therefore, obesity
Author for correspondence treatment interventions, including dietary strategies, are receiving increasing attention by
William Beaumont Hospital,
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 the form of drinks, bars and entrees work to replace food, restrict caloric intake and blunt
48073–1026, USA
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: enables weight reduction and have therefore been referred to as nutraceuticals – nutrition
wmiller@beaumont.edu
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 tions, as well as behavior modification
[2]. However, weight
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 lifestyles have likely tipped the energy balance have demonstrated superior weight-manage-
control, satiety, weight loss,
weight maintenance for most Americans (66%), and resulted in ment efficacy in comparison with all-food die-
overweight or obesity tary approaches. This article will review the
[1]. Several terms are used
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-
tric bypass surgery
diet’. Two or more MR shakes (equating to [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 mealreplacements
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
2
30 kg/m , 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.
2
40 kg/m , 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) future science groupfuture science group
Nutraceutical meal replacements – REVIEW
A),
Fiber (g) 5 5 3 5 5 0 2 1 5 , US
A
C
,
a
Sugar (g) 24 18 21 13 14 12 17 n/ 10 19 70 Carmel
s ,
u logy
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or chno
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Ph mg 280 350 350 280 400 140 175 140 210 140 200 ay
w
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and Nutr ,
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Calc ma
mg 400 500 500 400 600 250 250 280 400 200 400 th One ( ar
l Ph
i
r
† t
A u
N
(
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USA), Heakes
ss % RD 17 17 17 15 14 13 18 5 17 5 20 a
a Sh
Pot mg 600 600 600 550 480 460 630 180 580 200 700
ation, MN,
† A 60].
[ Corpor
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um year NJ
di % RD 9 8 9 11 11 9 12 11 11 3 23 tritio
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ent g ovartis N
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kc 220 190 190 190 170 160 160 110 160 100 160 s Slim-Fa
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T M r Sli O Sli Op Sli Pr Sli Car Slim-Fast with Soy Pr O to Drink Hea HMR HMR Pr Scan Diet *Perce † ‡ Meal replaceHMR n/
future science groupfuture science group www.futuremedicine.com 625
REVIEW – Miller, Nori Janosz, Zalesin & McCullough
Another study by Nielsen and Popkin exam- evidence that fat is not the most satiating
ining beverage intake in more than 73,000 macronutrient. In fact, fat is likely to be the
Americans between 1977 and 2001 found an least satiating macronutrient [13]. Instead, pro-
increase in energy intake from sweetened bever- tein appears to provide the highest satiety [14,15].
ages of 135% and a reduction of energy intake Studies examining both ratings of hunger fol-
from milk of 38%, resulting in a 278 total calo- lowing a protein preload as well as measurement
rie increase per person per day [9]. These of food intake have concluded that protein has
increases were associated with consuming larger the highest satiety.
portions as well as more servings per day of Studies examining carbohydrates and satiety
sweetened beverages. often reference glycemic index as a major stimu-
Evidence suggests that the larger the portion lus for insulin release. Glycemic index is defined
size, the larger the energy intake. Rolls and col- as the positive area under the glucose response
leagues found that subjects consumed 30% more curve after consumption of 50 g of available car-
energy when offered the largest portion than bohydrate from a food test. Glycemic index val-
when offered the smallest portion [10]. The ues are expressed relative to the glucose response
response to the variations in portion size was not observed after the same amount of a reference
influenced by who determined the amount of food, typically glucose or white bread [16].
food on the plate (subject vs investigator) or by Although the evidence is inconclusive, some
subject characteristics such as sex, BMI, or scores investigators have proposed that high glycemic-
for dietary restraint or disinhibition. Likewise, index-foods promote hunger and weight
Diliberti and colleagues found that when larger gain [17]. Shortly after ingestion of food, the gut
portion sizes are served at restaurants, more food secretes incretins, which work to signal the pan-
is eaten [11]. Hence, it is easy to see how growing creas to produce glucagon-like-peptide 1 and to
portion sizes in America have resulted in modulate the secretion of insulin in response to
increased calorie consumption. Since an blood glucose. Ingestion of a high-glycemic-
additional 100 kcal/day can lead to a weight gain index food results in a prompt and large increase
of 10 pounds over 1 year, inappropriate portion in plasma glucose. In response, there is a steep
size is likely to be a significant factor in rise in insulin secretion, resulting in clearance of
promoting obesity. blood glucose and relative hypoglycemia. This, in
As per the American Heart Association 2004 turn, is believed to promote increased appetite.
Scientific Statement on obesity, portion control Carbohydrates with a high glycemic index
is an important aspect of reducing energy intake include refined grains and potatoes. Low glyc-
[12]. Providing prepackaged prepared meals, emic index foods include high-fiber carbohy-
either as frozen entrees of mixed foods or liq- drates such as whole grains, most fruits,
uid-formula MRs, improves portion control nonstarchy vegetables and legumes. However,
and can enhance weight loss. MRs simplify por- other macronutrients ingested along with carbohy-
tion control during weight loss by eliminating drates alter the glycemic index. Combining protein
the need to measure or weigh food, or interpret with a carbohydrate, for example, results in a lower
food labels. However, education on appropriate glycemic index [18]. Foods with a lower glycemic
portion sizes and self-monitoring of energy index may help regulate satiety mechanisms [19]
intake is crucial for long-term maintenance of and body weight [20,21].
weight loss. In congruence with the concept of glycemic
index, fiber is also believed to have a high
Satiety satiating effect relative to fat and refined carbo-
Investigators have examined appetite and satiety hydrates. Proposed mechanisms include
in relation to food macronutrient composition. increased mastication time resulting in slower
Foods with high satiation per caloric density ingestion allowing satiety cues to take effect
could presumably aid in limiting overall energy prior to over-eating, a direct neural effect of the
intake. Among the macronutrients of fat, carbo- mechanical act of chewing on central satiety
hydrate and protein, fat was previously consid- centers [22], relatively low glycemic index and
ered to have the strongest effect on satiety. Fat the resultant gastric distention that occurs with
clears more slowly from the stomach so gastric high-fiber foods.
transit time is prolonged with fat intake as com- Another factor that may affect satiety is meal
pared with other macronutrients. More recent frequency. It is speculated that long intervals
investigation, however, provides compelling between feedings results in hunger that requires
626 Therapy (2007) 4(5) future science groupfuture science group
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