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According
to Good Housekeeping, the liquid diet drink trend began in the early 1930’s,
with “Dr. Stoll’s Diet-Aid, the Natural Reducing Food.” This low-calorie product, a combination of
milk chocolate, starch, whole wheat, and bran, mixed with water to create
drinks that replaced breakfast and lunch (http://homearts.com/gh/health/07nutrb2.htm). Since then, numerous liquid products and
other diet-aid derivatives have entered the market promising to shed weight and
encouraging healthy lifestyles. A
leading brand name on today’s market that makes such claims is Slim-Fast®.
The Slim-Fast® Mission Statement
“The Slim-Fast® Foods Company is
dedicated to the advancement of nutrition for good health” (http://www.slimfast.com/company/company.asp). The company is “committed to the development
of wholesome and balanced nutritional products to aid in weight management and
improved health” (http://www.slimfast.com/company/company.asp). Slim-Fast® offers a full line of
ready-to-drink shakes, powders, Ultra Slim-Fast® Nutritional Snack Bars,
Slim-Fast® Breakfast and Lunch Bars, and Slim-Fast® Meal On-the-Go Bars to
assist in weight loss, weight maintenance, and the development of healthy
eating habits.
Some General Terms: What does
that mean?
Body mass index (BMI) refers to the percentage of body
fat; it is the weight of an individual divided by their squared height. A BMI between 24 and 30 is considered
overweight for women, a BMI between 25 and 30 is considered overweight for men,
and a BMI greater than 30 is considered obese for both sexes (Kaplan, Sallis,
and Patterson, page 397).
Exercise is a subset of physical activity that involves
bodily movement but is planned, structured, and done repetitively to improve
and maintain one or more components of fitness (Kaplan, Sallis, and Patterson,
page 369).
Resting metabolic rate (RMR) is the rate at which
calories are burned when a person sitting quietly at rest (Kaplan, Sallis, and
Patterson, page 415).
Common Views of Weight
Crawford and Campbell (1999) found
that common definitions of weight differ drastically from medically accepted
BMI values. In this study, 1342
participants (666 men and 676 women) completed surveys in which they defined
ideal weight and the term ‘overweight.’
The average BMI value that women considered ideal was 22.7 and the
average ideal BMI value for men was 24.9.
Medically, a BMI value of 25 is considered overweight. In the study, however, women defined an
average BMI value of 23.7 as overweight and men defined an average BMI value of
26.1 as overweight. The BMI values for
ideal weight and overweight increased in both sexes with the participants’ ages
and current weights.
In
summary, men and women often do not have realistic images of their ideal weight
and/or being overweight. This fact can
create a problem when men and women strive for unrealistic weight goals.
The
Cut-and-Dry Rationale of the Slim-Fast® Treatment
The Slim-Fast® Company proposes a
comprehensive plan for weight loss and weight maintenance. The Plan for weight loss consists of
replacing two meals with Slim-Fast® shakes, eating one sensible meal, and
eating three healthy snacks each day.
For weight maintenance, the Plan includes replacing one meal with a
Slim-Fast® shake, eating two sensible meals, and eating three healthy snacks
each day. In the event of weight gain,
the company recommends restarting the weight-loss portion of the Plan for as
long as necessary to again reach an optimum weight (http://www.slimfast.com/plan/plan.asp).
Where Can I Purchase Slim-Fast® Products?
The Slim-Fast® Foods Company offers
the most comprehensive representation of its products at its official website (http://www.slimfast.com). However, the website does not provide a way
to order Slim-Fast® products. Thus, the
Slim-Fast® Foods Company recognizes that their product alone cannot
provide adequate nutrition or healthfully decrease weight. Although the company is looking to make money
from selling its products, it also exhibits a genuine interest in helping
people lose weight and maintain healthy lifestyles.
On the other hand, several websites,
such as http://buyinprivate.site.yahoo.net/buyinprivate/jumstardietp.htm,
http://st2.yahoo.net/moreonline/grocery-diet-aids-diet-aids---powder.html,
and http://www.marciaschs.com/p0000105.htm,
offer ways to purchase Slim-Fast® and other weight-loss and nutritional
products, but offer little or no information about these products. Thus, these companies strive solely to sell
the product and make money. Slim-Fast®
products are also readily available at most grocery, drug, and health food
stores.
Additional Advice to Complement the Slim-Fast® Plan
The
Slim-Fast® Foods Company website features advice about numerous dietary
strategies and tips for success. For
example, the company stresses the importance of counting calories as part of a
comprehensive weight-loss plan. The
company claims, “Most people consume more calories than they should each
day” (http://www.slimfast.com/plan/counting.asp);
however, the site offers no support of this claim. The company also claims that an individual
should cut 500 calories per day from his or her diet to lose weight at a rate
of one pound per week. Again, the site
offers no evidence that this information is accurate or that this rate of
weight loss is safe. However, the claims
are valid, as the FDA considers dropping 300 to 500 calories per day from a
current calorie intake effective to safely lose one to two pounds per week
(Department of Health and Human Services, 1996).
The
site also features common advice about healthy snacking (http://www.slimfast.com/plan/snacking.asp)
and portion sizes (http://www.slimfast.com/plan/portion.asp). It provides an example of a typical daily
menu (http://www.slimfast.com/plan/7daymenu.asp),
healthy recipes (http://www.slimfast.com/plan/menu.asp),
and cooking advice (http://www.slimfast.com/success/easy.asp).
The
company stresses realistic goal setting and expectations. The website claims that “For an initial
weight-loss goal, many health experts suggest 10% of your current body weight”
(http://www.slimfast.com/plan/plangoal.asp). However, the company offers no evidence in
support of this claim and does not recognize the specific “health experts” who
make this suggestion. As mentioned
earlier, under Common Views of Weight, men and women often do not have
realistic views of ideal weight. Thus,
this advice may prove difficult to follow.
The site also considers the helpfulness of a positive attitude (http://www.slimfast.com/success/power.asp)
and of having a weight-loss partner (http://www.slimfast.com/success/connect.asp),
but again offers no support of this advice.
The
company also stresses the importance of exercise as part of a comprehensive
weight-loss and weight-maintenance plan plan.
The web site claims, “Aside from changing the way you eat, exercise is
the most important step you can take to help you lose weight and improve your
health. People who include physical
activity in their weight-loss programs are more likely to keep the weight off
than are people who ONLY make dietary changes.
Any increase from your usual activity level helps you burn calories,
firm up, and improve your health” (http://www.slimfast.com/success/fit.asp). However, the site does not offer any evidence
to support the claims. Scroll down this
page to read more about exercise and weight loss, under Exercise.
The
website also presents common lifestyle tips for successful weight loss and healthy
eating habits (http://www.slimfast.com/success/life.asp),
such as identifying vulnerable over-eating situations, avoiding temptations,
and shopping tips. Scroll down this page
to read more about planned grocery shopping, under Shop With a List.
Exercise
Something
to think about: When farmers fatten up
animals to sell, what do they do? Well,
for one, the farmers coop up the animals, limiting their physical activity
(Zachwieja, 1996). Hmm.
Several
review papers that summarize studies concerning exercise and weight loss stress
the same points. First, the addition of
physical activity to a calorie-restricted diet produces better weight loss
results and weight maintenance success than a calorie-restriction diet
alone. Second, physical activity may
create a more favorable body composition than a calorie-restricted diet. Calorie-restricted diets often burn lean body
mass, whereas physical activity burns fat while promoting lean body mass. Third, an energy expenditure of at least 1500
calories per week is sufficient to maintain weight loss. Fourth, exercise has benefits other than
weight loss, such as lowering rates of morbidity and mortality, increasing
resting metabolic rate, lowering blood pressure, improving cardiovascular
function, and reducing cholesterol levels.
Thus, these review papers support the claims about the importance of
exercise in weight loss and weight maintenance made by the Slim-Fast® Company.
Shop With a List
In a prospective study by Beneke,
Davis, and Vandertuig (1988), a group of women planned their families’ meals
for the week, transferred the ingredients needed to a grocery list, and
organized the list according to the layout of their grocery store. This study showed that the planned shopping
with a list helped to reduce weekly food purchases, including spontaneous
purchases of high-fat, attractive foods, as compared to a group of women who
did not plan their shopping. The study
also showed that the decrease in food purchased often corresponded with weight
loss. Thus, this study supports the
advice offered by the Slim-Fast® web page about planned shopping.
Is the Plan Effective?
Slim-Fast®’s Testimonials of Effectiveness
The Slim-Fast® web page showcases
the testimonials of four individuals, each who lost miraculous amounts of
weight and lead amazingly healthy and energetic lives by following the
Slim-Fast® Plan (http://www.slimfast.com/testimonials/testimonials.asp). Interestingly, each testimonial ends with the
statement “Results not typical.” In the
question portion of the site, the company states that “Clinical studies show
that weight loss varies with the individual and averages 1 to 2 pounds per
week” (http://www.slimfast.com/qa/average.asp). Relatedly, several individuals have posted
Slim-Fast® success stories on the Internet at sites such as http://www.physical.com/jchatter/messages. Scroll down this page to read more about the
evidence supporting and debunking these claims, under A Study Supporting
Slim-Fast, Another Study Supporting Slim-Fast, and A Study of the
Maintenance of Weight Loss.
Slim-Fast®’s Claims and Proof
Slim-Fast® claims “Randomized
clinical trials show that patients who follow the Slim-Fast® Plan lose more
weight than those on standard diets and they keep the weight off” (http://www.slimfast.com/medical/medical.asp). The Slim-Fast® web page offers proof of their
claims in the form of two clinical studies, summarized at http://www.slimfast.com/medical/m_ditsch.asp
and at http://www.slimfast.com/medical/heber.asp. Scroll down this page for more complete
analyses of these studies, under A Study Supporting Slim-Fast® and Another
Study Supporting Slim-Fast® and for an additional study of weight
maintenance, under A Study of the Maintenance of Weight Loss. In summary, the Slim-Fast® Company offers
sound evidence to support their weight-loss claims.
A Study Supporting Slim-Fast®
Ditschuneit, Flechtner-Mors,
Johnson, and Adler (1999) found that meal replacements such as Slim-Fast® are
effective in long-term weight loss and weight maintenance. Their study had two phases. The first phase was a prospective study that
lasted three months and compared two diet plans to determine which produced
better weight loss results, as described below.
The second phase lasted two years and studied the maintenance of one
diet plan, also described below. The 100
participants in this study were men and women over the age of 18 with body mass
indexes between 25 and 40 who were dissatisfied with previous
calorie-restriction diets. Prior to
phase 1 of the study, the participants were randomly assigned to either group
A, which contained 41 female and 9 male participants, or group B, which
contained 38 female and 12 male participants.
All participants received monthly instruction and feedback from a
nutritionist concerning food choices, meal planning, portion sizes, and the
construction of a food diary. During
both phases, both groups were instructed to eat three meals and two snacks
daily. Participants in group A selected
their own meals and snacks from regular food.
Participants in group B, however, replaced two meals and both snacks
with Slim-Fast® products. In phase 2 of
the study, both groups replaced one meal and one snack with Slim-Fast®
products. Participants reported monthly
for weighing and measuring.
At the end of phase 1, men in group
A lost 1.1 + 2.6 kg, men in group B lost 8.4 + 3.9 kg, women in
group A lost 1.2 + 2.1 kg, and women in group B lost 6.8 + 3.3
kg. At the end of phase 2, both groups
lost weight at approximately the same rate.
At the end of the study, group A had lost 5.9 + 5.0% of their original
body weight and group B had lost 11.3 + 6.8% of their original body
weight. A total of 37 participants
dropped out of the study for various reasons, but this did not significantly
affect the results of the study. This
study also addressed the decrease of certain risk factors for disease, such as
blood pressure and cholesterol, that accompany weight loss. In summary, this study supports the claims
that Slim-Fast® products are effective in initial weight loss and in weight
maintenance.
Another Study Supporting Slim-Fast®
Heber, Ashley, Wang, and Elashoff
(1994) found that continued use of a meal replacement, such as Slim-Fast is an
effective way to lose weight and maintain long-term weight loss. They also found Slim-Fast® to be effective in
initial weight loss. This study actually
addressed the entire Slim-Fast® Plan, as a low-fat diet accompanied the use of
the products. The prospective study took
place in two time frames: an initial
12-week weight-loss period and a subsequent 104-week maintenance period. The participants in this study were 71 mildly
obese males with an average age of 38.7 years and an average of 119% of ideal
body weight and 230 mildly obese females with an average age of 38.3 years and
an average of 122% of ideal body weight.
Participants received minimal nutritional information and feedback
during the study. During the initial
weight-loss period, participants were instructed to replace two meals with
Ultra Slim-Fast® products and to eat one balanced meal, for a total of 1000-1200
calories daily. The participants
reported weekly for weighing and rated the taste, appetite satisfaction,
convenience, overall rating, general well-being, and energy level of the weight
loss program. After the first 12 weeks,
35 participants who lost less than nine pounds during the first time frame were
considered non-adherent and were excluded from the study. During the second time frame, the remaining
participants replaced one meal per day with a Slim-Fast® product and ate two
well-balanced meals to lose weight or maintain their desired weight. The participants reported bi-weekly for
weighing.
273 participants remained in the
study for the first time frame. At the
end of the 12-week time period, the men in the study lost 18.6 + 7.0
pounds and reduced their percentage of ideal body weight to 108 +
5%. The women in the study lost 14.0 +
6.5 pounds and reduced their percentage of ideal body weight to 111 +
7%. A significant number, 44.1%, of
participants dropped out or were excluded from the study during the second time
frame. After one year, 184 participants
remained in the study: 41% of the
participants weighed less than their 12-week weight, 67% of the participants
kept 80% of their weight loss off, 22% of the participants kept a portion (below
80%) of their weight loss off, and only 0.5% of the participants weighed more
than their original weight. After two
years, 136 participants remained in the study:
22.8% of the participants weighed less than their 12-week weight, 39% of
the participants kept 80% of their weight loss off, 30.9% kept a portion (below
80%) of their weight loss off, and 7.4% of the participants weighed more than
their original weight. The weight loss
also provided benefits, such as lowering cholesterol levels. In summary, this study supports the claims
that Slim-Fast® products are effective in initial weight loss and in weight
maintenance, even in self-directed programs.
A Study of the Maintenance of Weight Loss
McGuire, Wing, Klem, Seagle, and
Hill (1998) studied the weight-loss maintenance techniques of 893 people, 81%
female and 19% male, who had lost weight on their own (447 participants),
through organized programs (313 participants), or with a liquid diet-aid (133
participants). The participants were
members of the National Weight Control Registry (NWCR), over the age of 18, had
lost over 30 pounds, and had kept the weight off for at least one year. Through questionnaires, the researchers
gathered background data from the participants:
current height, current weight, maximum lifetime weight, amount of
weight cycling, and disease history. The
questionnaires also gathered information concerning the recent weight loss that
qualified the individual for the study:
time taken to lose the weight, a reference physician to prove the weight
loss, and motivation for the weight loss (medical, emotional, or life
events). The participants rated the
perceived level of difficulty of losing the weight and the level of difficulty
of maintaining the weight loss on a scale of one to seven. Further questions determined the dietary
strategies that the participants used for their weight-loss maintenance: counting calories, counting fat grams,
limiting calories from fat, limiting quantity of food eaten, limiting certain
foods, limiting certain groups of food, using a liquid diet-aid, using a
structured diet or program, and frequency of weighing. A Block Food Frequency Questionnaire (BFFQ)
detailed the dietary energy intake from fat, carbohydrates, and proteins. An Eating Inventory further assessed dieting
behavior. A Paffenbarger Activity
Questionnaire (PAQ) determined weekly calorie expenditure to exercise.
The On Own group had greater
difficulty in losing the weight, mostly likely due to the lack of professional
instruction, and reported the least difficulty in maintaining the weight
loss. The On Own group used exercise to
maintain weight loss and rarely used dietary strategies. The Liquid Diet group had the most medical
problems and lost the most amount of weight, but were still the heaviest
individuals in the study and had the most medical problems. The Liquid Diet group used dietary
strategies, such as counting calories, limiting fat, and using a liquid diet
aid, to maintain weight loss, but reported the most difficulty maintaining the
weight loss. In summary, this study
recognizes that a liquid meal replacement is effective in treating obese
patients, thus supporting the claims made by the Slim-Fast® Company. However, this study also notes the extreme
importance of physical activity in maintaining weight loss.
Conclusion
In conclusion, the comprehensive
Slim-Fast® Plan, including meal replacement, healthy eating, and exercise, is
an effective method to lose weight and maintain weight loss. Thus, the weight-loss claims found on the
Slim-Fast® web page are valid and the Slim-Fast® site is a valuable tool for
information concerning weight loss.
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