Fad Diets: Do They Work?
Medical Considerations
Jessica McCourt
Masters Project
Spring 2008
Gilbert Boissonneault
Outline
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Introduction
How to spot a fad diet
Discussion of different fad diets
Why fad diets “work”
Why fad diets don’t “work” and medical
considerations
 Healthy eating and exercise
Introduction
 American Obesity Association reports (AOA 2005)
 127 million US adults are overweight
 60 million are obese
 9 million are severely obese
 Totaling over one-third of the adult American
population
 Obesity is associated with more than 30 medical
conditions.
 Including diabetes, osteoarthritis, coronary heart
disease, respiratory problems, and hypertension.
 Weight loss of about 10% of body weight can improve
some obesity-related medical conditions.
Introduction
 American Obesity Association
 genetics
 environmental exposure to an energy-rich food
supply
 a tendency to reduce physical activity and personal
behavior
 The American Dietetics Association
 increased per capita caloric consumption
 larger portion sizes
 lack of adequate physical activity
Introduction
 National obsession
 Americans spend an astonishing $33 billion a year on
weight loss plans and services
 Consequently, fad diet plans that promise dramatic
results have become very popular.
 More than two-thirds of Americans are either dieting to
lose weight or watching what they eat to keep from
gaining weight
 More than one in five dieters used fad diets
How to spot a fad diet
 Fad diets can be quite convincing to the average
person
 Offer a quick solution to a long term problem
 Author or creator presents what appear to be
scientifically valid explanations to support the dieting
theory.
 The individual marketing or promoting the diet may be
tertiary educated, although frequently has no formal
nutrition or dietetic qualifications.
 The theory is often explained using scientific
terminology, which may or may not be understood by
the consumer
 Most of the "evidence" for fad diets is based on
theories and testimonials of short term results.
Discussion of fad diets:
Atkins
 Limit the intake of starchy, high carbohydrate foods
 Consuming more carbohydrate than can be used by
the body it will store this excess in fat cells
 Without carbohydrates however, fat is not burned
completely and substances called ketones are formed
 According to Dr. St. Jeor “abnormally high ketone
levels in the body, or ketosis, may indeed make dieting
easier since they typically decrease appetite and cause
nausea. Ketosis also increases the levels of uric acid
in the blood, which is a risk factor for gout and kidney
disease in susceptible people” (Jeor 2000).
 Atkins diet could lead to halitosis, constipation, heart
disease, bone loss, colon cancer, and kidney damage
Discussion of fad diets:
Zone
 40% carbohydrates, 30% protein, 30% fats
 For many individuals this precise ratio is not feasible to
follow for every meal of the day and would take a lot of
preparation time
 The diet is also a low calorie diet, so you can't help but
lose weight.
 According to Samuel Cheuvront, PhD, RD the precise
protein to carbohydrate ratio required with each meal is
promoted to ultimately produce a cascade of events
leading to a reduction in chronic disease risk, enhanced
immunity, increased longevity and permanent weight loss.
 “A review of the literature suggests that there are
scientific contradictions in the Zone Diet hypothesis that
cast unquestionable doubt on its potential efficacy”
(Cheuvront 2003).
Discussion of fad diets:
Blood Group
 This diet depends on having a blood test and
determining your blood type
 Different blood groups can eat different food groups.
 For example the A group diet excludes dairy and meat
products. Removing dairy products completely from the
diet can lead to a calcium deficiency, which can put you
at risk of osteoporosis. Avoiding meat can result in low
intakes of iron, which can lead to anemia. In the long
run, removing any food group entirely can result in a
poor intake of nutrients which are needed for good
health (Kellow 2007).
 By eliminating whole food groups important nutritional
deficiencies are likely associated with long term health
problems.
Discussion of Fad Diets:
Hay
 Do not eat protein and carbohydrates together.
 Combination of eating these two foods together
appears to prevent protein from being digested in the
gut and can lead to an accumulation of toxins.
 A study performed at the University of Rostock in
Germany “was to evaluate the metabolic effect of the
Hay diet on protein turnover, fat oxidation, respiratory
quotient, body fat and weight loss. Twelve healthy
adults received an individually regular diet and
thereafter a 10-day Hay diet. The Hay diet did not
reduce total body water, lean body mass, body fat and
body weight” (Wutzke 2001).
Discussion of fad diets:
Cabbage soup/Grapefruit
 Basically the same
 Consume a specific food everyday for each meal.
 Both have weight loss, but mainly because of the
strict calorie restriction.
 Weight loss is mostly 'water' weight.
 The thing is who can stick to just eating cabbage
soup or grapefruit for an extended period of time?
 Once the diet is discontinued the weight will
immediately be regained.
Why fad diets “work”
 Work short term because calorie intake as a result of
the diet is usually lower than the person's basal
metabolic requirements.
 This is the only way to lose weight: to consume less
energy than the body needs.
 The rate of weight loss varies depending on the relative
proportions of the three major nutrients in the diet:
carbohydrate, fat and protein.
 This also includes shift in water weight.
 The rate of anticipated weight loss will vary according
to the age, sex, weight, basal requirements, and
activity level of an individual.
Why fad diets don’t “work”
and medical considerations
 David Roberts, professor of Nutrition and Dietetics,
says that “fad diets are generally nutritionally
unbalanced and lack essential nutrients” (Roberts
2001).
 When weight loss is too fast, especially the loss of lean
body mass, this can cause obesity in the longer run.
 One large study reported an overall increased risk of
major weight gain in the long term in those who
undertook weight-loss attempts (dieting) at baseline
(Roberts 2001).
 By omitting certain foods, and sometimes even entire
food groups, these diets are deficient in major nutrients
 Some of the diets are also out of balance
Why fad diets don’t “work”
and medical considerations
 All fad diets tend to promote the loss of water weight.
 If an imbalanced diet is maintained, the body soon reverts to
a fasting state called ketosis
 The body is actually tricked into thinking it is a starvation
mode.
 Authors of many of these fad diets actually advocate "taking
advantage" of ketosis to hasten weight loss.
 Deliberately inducing ketosis can lead to muscle breakdown,
nausea, dehydration, headaches, light-headedness,
irritability, bad breath, and kidney problems.
 In a randomized weight loss study comparing ketogenic and
non-ketogenic low-calorie diets, the subjects on the
ketogenic diet had impairments in higher order mental
processing than those on the nonketogenic diet (Denke
2001).
Why fad diets don’t “work”
and medical considerations
 In the long run fad diets make a person
fatter instead of leaner, because each
time the diet is stopped it is easier to
regain fat that was originally lost.
 Perhaps what is most concerning about
fad diets, regardless of whether they
work, is that they could ultimately
encourage unhealthy attitudes towards
food and eating.
Healthy eating and
exercise
 Very simple dietary changes can produce effective weight
loss at a healthy rate that can be maintained over the longer
term.
 Your starting weight, exercise level, and basal metabolic
rate determine the total amount of calories that is right for
your diet program.
 Patients and their health care providers must be conscious
of health concerns when choosing a plan for weight loss
because dietary change is meant to be a long-term process
(Ma 2007).
 A “gradual and balanced” approach is best for those who
really want to lose weight, said Vivian Crisman a nutritionist
(Miller 2003)
 Healthy lifestyle habits will help maintain long-term weight
control, which includes regular aerobic and weight training
exercise, behavior modification, and a healthy, nutritious diet
with a wide variety of foods.
Healthy eating and
exercise
 The word diet originally comes from the
Greek root meaning, "way of life."
 Scientists and nutritionists agree that any
long-term program of weight loss and
maintenance must be more than a matter
of for example removing carbohydrates
and counting calories. It must extend to
the entire "way of life."
References
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