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t_Articles
The festive season is over and those persistent few pounds are
hanging on. Time for the latest fad diet?
Most of us have been on a fad diet at some stage in our lives or we
have known someone who has. Whether it's eating grapefruits until we
can't stand the sight of them or juggling with combinations of different
foods, dieting is not easy. Sadly, in the majority of cases, fad diets
just don't work.
While Asia still has a long way to go to reach the incidence of
overweight in countries like the United States, Britain and Australia,
overweight is becoming increasingly common in this part of the world.
Estimates show that as many as 20 percent of adults in some Asian
countries are overweight. It's little wonder that they are turning to
methods to help them lose weight quickly. But do weight control diets
actually deliver what they promise? And how do you rank the "good" from
the "bad" when it comes to weight control strategies?
"Fad diets are not the way to go," says Dr. Corazon VC Barba,
Director, Food and Nutrition Research Institute, Metro Manila,
Philippines . "Fad diets are a short-term, quick fix approach and do not
deliver lasting weight loss. Food choices are usually very limited and
kilojoule intakes are often very restrictive. Once the novelty wears
off, so does the motivation to continue," she said.
The diet debate
In February 2000, the United States Department of Agriculture (USDA)
sponsored a meeting called "The Great Nutrition Debate", a discussion
panel that featured popular diet book authors as well as nutrition and
weight loss researchers. The panel failed to reach any consensus on the
best way to approach weight loss - not surprising given the widely
differing views available in the popular press.
In the end, the USDA indicated that it would be timely for government
researchers to evaluate commonly used weight loss diets to help sort
fact from fiction. The department noted that there is a dire lack of
scientific research to support the theories expounded in the majority of
diet books currently on the market. Most diet books promise weight loss
programmes that are easy to follow, that allow favourite foods or foods
traditionally limited in weight loss diets, and that place no real
emphasis on physical activity.
"Fad diet book authors often take a scientific half-truth that is
complex and use that as the basis of their arguments," said Dr.Barba.
"Authors may simplify or expand upon biochemistry and physiology in an
effort to help support their premises and provide a plethora of
scientific jargon that people do not understand but that seems to make
sense. Few if any of these books offer solid scientific support for
their claims in the form of published research studies. Instead, most
evidence is based on anecdotal findings, theories and testimonials of
short-term results."
Low carbohydrate, high protein diets
Some of the most popular diets to hit the bookstore shelves these
days promote low carbohydrate and high protein intakes. These diets are
nothing more than low calorie diets in disguise but with some
potentially serious consequences. Following a low carbohydrate, high
protein diet encourages the body to burn its own fat. Without
carbohydrates however, fat is not burned completely and substances
called ketones are formed and released into the bloodstream. 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. These diets
can also result in dehydration, diarrhoea, weakness, headaches and bad
breath. Over the long term, they may increase the risk of osteoporosis
and coronary heart disease.
POPULAR FAD DIETS
Here's a rundown on some of the more popular diets that are making
headlines
Low carbohydrate, high protein diets (such as Dr Atkin's Diet)
Premise or theory that the diet is based on:
Excess carbohydrate intake prevents the body from burning fat
efficiently. Eating too many carbohydrates causes production of
excessive amounts of insulin, leading to obesity and a variety of other
health problems. Drastically reducing dietary intake of carbohydrates
forces the body to burn reserves of stored fat for energy, a condition
known as "ketosis". This in turn leads to decreased hunger and a
metabolic advantage.
Dietary recommendations made:
Most of these diets limit carbohydrates to 20 grams per day for
the induction phase of the diet and 0 to 60 grams in the ongoing
weight loss phase. Carbohydrate intake ranges from 25 to 90 grams
daily in the maintenance phase.
Nutritionists' comments:
There are no published scientific studies to support the claims
made.
The diet relies on the fact that reducing carbohydrate intake
causes the body to lose fluid. This shows up as kilograms lost on the
scales however such "results" are short-lived as the lost fluid soon
returns and the scales creep back up again.
The eating plans usually offer very limited food choices.
The diets are nutritionally unbalanced and excessively high in
protein, fat, saturated fat and cholesterol.
The diets promote ketosis as a means of weight loss.
Dehydration is possible if large amounts of water are not
consumed.
The diet is low in calcium, magnesium, vitamin C and folate
(dietary supplements are recommended).
The "Zone" diet
Premise or theory that the diet is based on:
The "zone" is a metabolic state in which the mind is relaxed and
focused and the body is strong and works at peak efficiency. A person in
the "zone" will allegedly experience permanent body fat loss, optimal
health, improved athletic
performance and better mental productivity. Insulin is released as a
result of eating carbohydrates and this leads to weight gain. Because
food has a potent, drug-like effect on the hormonal systems that
regulate the body's physiological processes, eating the right
combination of foods leads to a metabolic state (lower insulin and lower
eicosanoid levels) in which the body works at peak performance and which
results in decreased hunger, weight loss and increased energy.
Eicosanoids are compounds that are involved in a wide range of body
processes such as synthesis of certain fatty acids.
Dietary recommendations made:
To get into the "zone", rigid quantities of food, apportioned in
blocks and eaten at prescribed times, are recommended in a
distribution of 40 percent carbohydrate, 30 percent protein and 30
percent fat. Meals should provide no more than 2,100 kilojoules (500
kilocalories) and snacks less than 420 kilojoules (100 kilocalories).
Food should be treated like a medical prescription or drug.
Menus suggest lots of egg whites, nuts, olives, peanut butter and
mono-unsaturated fats and large amounts of allowable fruits and
vegetables. Alcohol is allowed in moderation but "zone" followers are
advised to avoid or limit carbohydrates, especially pasta, bread,
certain fruits and vegetables, such as bananas and carrots, and
saturated fat.
The diet averages 5,400 kilojoules (1300 kilocalories) per day
although some menus run as low as 3,600 kilojoules (860 kilocalories).
Nutritionists' comments:
The diet oversimplifies complicated physiological processes. For
example, eicosanoids are one part of a complex system and no studies
suggest that they are dangerous or cause disease.
The metabolic pathways that supposedly connect diet, insulin-glucagon
and eicosanoids are not found in standard nutrition or biochemistry
texts. The premise that any type of diet completely controls insulin
and glucagon secretion is not supported by current nutrition or
biochemistry knowledge. Glucagon has an effect opposite to that of
insulin. Insulin's and glucagon's opposite actions help regulate
carbohydrate metabolism.
The diet relies upon unproven claims based on case histories,
testimonials and uncontrolled studies that are not published in
peer-reviewed journals.
The "Eat-all-you-want-of-one-type-of-food" diet
Theory/premise that the diet is based on:
Whether it's bananas, pasta or eggs, this diet is based on the theory
that after one or two days the dieter will become so bored with the
limited repertoire of foods that he or she will reduce their kilojoule
intake dramatically. Few people can eat very large amounts of one
particular food only so energy intake drops markedly.
Dietary recommendations made:
Generally you can eat as much as you like of one food or a limited
selection of foods. All other foods are restricted.
Nutritionists' comments:
Any weight loss is due to the fact that kilojoule intake is
dramatically reduced.
The diet cannot be followed long-term as it is deficient in many
vitamins and minerals.
Food Combining diets
Theory/premise the diet is based on:
Excess body fat is due to "improper food combinations". The idea is
based on a belief that proteins need an acid environment for digestion
while carbohydrates need an alkaline one.
Dietary recommendations made:
Followers are usually advised to take only fresh fruits and juices in
the morning. They must also avoid combining protein foods (such as meat
and dairy products) with carbohydrate foods (like bread and pasta).
Nutritionists' comments:
The idea that protein and carbohydrate cannot be taken together is
based on erroneous theories regarding digestion. The body is perfectly
capable of digesting mixtures of nutrients. The stomach is an acidic
environment while the small intestine is alkaline. Digestion of
protein starts in the stomach and is continued in the small intestine
where most food digestion occurs.
Most foods contain a mixture of protein and carbohydrate.
Any weight loss is due to a lowered intake of kilojoules because
of the limited number of foods allowed.
The Bottom Line
Although all of these diets may promote short-term weight loss, their
long-term effectiveness is a different story. The bottom-line for
lasting and healthful weight loss is a varied diet, reduced kilojoule
intake and regular physical activity.
"The truth is that losing weight permanently takes work. It is not
glamorous - eating habits need to change and activity usually needs to
increase," notes Dr. Barba. "If a diet sounds too good to be true, it
probably is."
Tips on spotting fad diets
Claims or implies a large or quick weight loss of more than 0.5 to
1 kilogram per week. Slow gradual weight loss increases the chance of
weight loss success and of keeping weight off over the long term.
Promotes magical or miracle foods. No foods can undo the long-term
effects of overeating and not exercising or "melt away fat".
Restricts or eliminates certain foods, recommends certain foods in
large quantities, insists on specific food combinations or offers
rigid inflexible menus.
Implies that weight can be lost and maintained without exercise
and other lifestyle changes.
Relies heavily on undocumented case histories, testimonials and
anecdotes but has no scientific research to back up claims.
Contradicts what most trusted health professional groups say or
makes promises that sound too good to be true.
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