The American Institute for Cancer Research has evaluated four of the most
popular diet books of the moment. We wondered if, beneath the promises,
any of these books offered advice about nutrition and weight loss that was
based on sound science. We analyzed the potential effectiveness and
possible health risks associated with each plan.
We discovered that all four share many of the same basic
characteristics – characteristics that illustrate the limitations of fad
diets in general.
books reviewed were:
- Dr. Atkins New Diet Revolution, by Dr. Robert Atkins
- The New Beverly Hills Diet, by Judy Mazel and Michael
- Protein Power, by Michael Eades, MD and Mary Anne
- Suzanne Somers' Get Skinny on Fabulous Food, by
1. All four of the plans reviewed are essentially low calorie
diets. None are advertised as such, however. In fact, each encourages the
dieter to eat as much as he or she wants of a particular food. Nevertheless,
these diets prescribe a daily caloric intake that is well below average
2. By omitting certain foods, and sometimes even entire food
groups, these diets are deficient in such major nutrients as dietary fiber and
carbohydrates, as well as in selected vitamins, minerals, and protective
phytochemicals. Dr. Atkins, for one, recommends supplementing the diet with
nutritional supplements – and helpfully offers his own line of products.
3. The diets are also out of balance, prescribing a daily
dietary intake that is high in protein and fat, low in carbohydrates. These
proportions are a far cry from those recommended by AICR and other major health
organizations like the American Heart Association and the American Dietetic
Association, as well as the Surgeon General and the United States Department of
4. On a practical level, such high-protein, high-fat,
low-carbohydrate diets tend to promote the loss of water weight. However
much this diuretic effect may engender a false sense of accomplishment in the
dieter, this weight can and does return quickly.
5. If such an imbalanced diet is maintained, the body soon
reverts to a fasting state called ketosis, in which the body begins to
metabolize muscle tissue instead of fat. Authors of these diets actually
advocate "taking advantage" of ketosis to hasten weight loss. In fact, this
state is one of the body's last-ditch emergency responses; deliberately inducing
ketosis can lead to muscle breakdown, nausea, dehydration, headaches,
light-headedness, irritability, bad breath, and kidney problems. In pregnancy,
ketosis may cause fetal abnormality or death. It can be fatal in individuals
6. Over an extended period of time, all four diets can give
rise to other health risks, as well. By restricting carbohydrates, all four
diets inevitably lead to a lack of fiber, which can cause constipation and other
gastrointestinal difficulties. In addition, the high amounts of cholesterol and
saturated fat they prescribe increase the risk of heart disease and, possibly,
some cancers. There is recent evidence that a diet featuring excessive protein
may leach calcium from the bones.
7. Over and above these health
risks, however, two of the diets discussed below promote baseless ideas about
"food combinations." The elaborate case they make for eating specific foods
in a specific order and at specific times has no nutritional basis, and amounts
to a kind of magical thinking. Click here to read more about the Glycemic Index, a
controversial nutritional concept that many authors of fad diets point to as
proof of their theories.
Below we examine each diet plan in greater depth.
Dr. Atkins' New Diet Revolution, by Dr. Robert C. Atkins,
This book is simply an update of Dr. Atkins' previous diet, recycled here
perhaps to encourage the sale of dietary supplements. Besides the health risks
associated with ketosis outlined earlier, there are other long-term concerns
associated with this particular plan.
Atkins' diet can lead to the kind of rapid weight fluctuations that adversely
effect the heart. Moreover, the breakdown of fatty acids that occurs during
ketosis may also increase the risk of heart disease.
One of the basic tenets of Atkins' diet is that sugar causes cancer. Such
misleading pronouncements are essentially scare tactics, meant to direct the
dieter towards foods on the Atkins plan.
Finally, nothing about this plan encourages the dieter to learn some very
basic weight management strategies like portion control and serving sizes, let
alone develop the skills necessary for a lifetime of balanced nutrition.
The New Beverly Hills Diet, by Judy Mazel and Michael Wyatt
Ms. Mazel has no health or nutrition credentials. Her "New Beverly Hills
Diet" is fundamentally flawed, which curtails any potential long-term
effectiveness and even gives rise to certain risks. Specifically, two of Ms.
Mazel's theories about digestion are wrong.
The premise of her diet is that enzymes found in food "activate" the human
body. Each of the three food groups – proteins, carbohydrates and fats – contain
their own set of enzymes to break down food so that the body can properly digest
Mazel advocates a practice she terms "Cautious Combining." "It is when you
eat and what foods you eat together that matters," she claims. Fruits, for
example, contain all of the enzymes necessary to break themselves down into
nutrients, and move quickly through the system. Proteins and carbohydrates,
however, require special enzymes that slow down the process. Furthermore,
enzymes from one food can't "cross over" to work on other food groups.
These suppositions are incorrect. The enzymes necessary for digestion are
found within the body, not in the foods we eat.
Mazel also states that fat is just another symptom of indigestion, that when
food is not properly digested, it "causes fatness."
In fact, quite the opposite is true – if foods are not properly digested they
cannot be absorbed. If they are not absorbed, they cannot be metabolized – into
fat or anything else.
On a more practical level, Mazel encourages consuming a single food – grapes
for example – for an entire day. This is not only nutritionally inadequate, it
is also boring. Thus, it is not a strategy likely to be sustained.
Mazel's plan ends up promoting a wide range of
fundamentally unhealthy habits. Of equal concern, however, are the healthy
habits it doesn't mention. Mazel, like Atkins, neglects to address portion control and serving
sizes, concepts central to any serious program of long-term weight
management. Perhaps most puzzling, however, is Mazel's silence on the subject of
exercise. Regular physical activity it crucial for losing and maintaining
weight, but the closest Mazel gets to this topic is her admonition to chew food
Protein Power, by Michael Eades, M.D. and Mary Dan Eades,
Of the four diets reviewed, Protein Power gets the most credit for providing
sound starting points for weight loss. The authors advise getting a physical
exam, setting realistic baselines involving body fat percentages and ideal body
weight, relying on internal perceptions rather than the bathroom scale, keeping
a food diary, and drinking lots of water. The diet itself, however, places the
individual at risk for many of the same problems seen in the other diets
The name of the plan itself, Protein Power, is misleading. The authors
recommend 60 grams of protein a day for a relatively active individual with a
lean body mass of 100 pounds. But 60 grams of protein is nothing more than the
USDA recommended daily allowance for a person of that weight. In fact, the
average American normally eats around 100 grams of protein a day. The Protein
Power plan simply cuts carbohydrates, producing what is essentially a
Which brings us to the plan's directive to consume 25 grams of fiber daily
while maintaining a low-carbohydrate intake. This is effectively impossible, as
most high fiber foods contain significant amounts of carbohydrates.
The authors blame insulin for a host of ills,
including hypertension, heart disease, elevated cholesterol and diabetes. High
insulin levels, they say, lead to weight gain and obesity. In fact, the
scientific evidence suggests that being obese causes high insulin levels, not
the other way around. (The Eades theory relates – very loosely – to a
controversial nutritional concept called the Glycemic Index.)
Finally, the Eades emphatically state that resistance training (lifting
weights) is "better" than aerobic activity. No reliable science suggest one of
these two forms of exercise is superior – both are equally important for overall
fitness and weight management.
Susanne Somers' Get Skinny on Fabulous Food, by Suzanne
Before she began penning diet books, the only remotely health-related entry
on Suzanne Somers' resume was an infomercial for a thigh exerciser. She brings
no nutrition credentials to bear on this book, which blames excess fat on the
tendency of the body's enzymes to "cancel each other out." Her solution, a
Byzantine process of eliminating "Funky Foods" and separating the rest into
"Somersized Food Groups" for mixing and matching, has no nutritional basis.
Somers maintains that when proteins and carbohydrates are eaten together,
their enzymes "cancel each other out," creating a halt in the digestion process
and causing weight gain.
Unfortunately, this reasoning is based on assumptions that are completely
false. In fact, the body contains enzymes that are specifically keyed to
individual proteins, carbohydrates and fats. These enzymes do not "cancel each
other out," because they remain in different areas of the digestive tract.
Furthermore, if digestion did not occur, the resulting lack of protein and
carbohydrate absorption would most likely result in weight loss, not the weight
gain Somers' predicts. Somers' advice not to drink water with meals because it
dilutes the digestive juices and slows digestion is also without merit.
In most other particulars, the Somers's plan closely resembles the three
diets AICR reviewed above, and places the dieter at similar risk.
In defending her high-fat plan, Somers states that no reliable long-term
studies have shown any negative effects associated with increasesd fat
consumption. This is an untrue assertion. A 1997 AICR report,
Food, Nutrition and the Prevention of Cancer: A Global Perspective, identified numerous studies possibly
linking a high-fat intake with increased risk of several cancers and other
chronic diseases. The report went on to develop a set of general
dietary guidelines that protect against disease while promoting overall health.
Why Fad Diets Don't Work
The notion of the "quick fix" is central to all fad diets. So, too, is the
mistaken belief that a change in our bodies can only result from a radical
change in how we eat. After all, we look to these diet plans not for help making
gradual, long-term adjustments to our overall lifestyle, but to "melt fat in
just two weeks!"
That's an important distinction. The word diet originally comes from the
Greek diaita, which means "manner of living." Scientists and nutritionists agree
that any long-term program of weight loss and maintenance must be more than a
matter of rationing carbohydrates and calculating calories. It must extend to
the entire "manner of living."
The Glycemic Index: What It Is and What It Is Not
According to many popular fad diets, foods that rapidly raise blood sugar
levels are responsible for making you fat. Specifically, the four
low-carbohydrate, high-protein plans reviewed by AICR attempt to blame
overweight and obesity on high insulin levels. They maintain that by avoiding
foods that trigger the body to release insulin in great amounts, it is possible
to lose fat quickly and permanently.
To make this claim, the fad diet authors ignore the substantial amount of
research that runs counter to their "theory." More importantly, however, they
have taken a controversial nutritional concept – the Glycemic Index – out of the
context for which it was intended. To understand how they have manipulated a
scientific idea to bolster their claims, it is important to understand what the
Glycemic Index actually is.
The Glycemic Index was first developed in 1981 by scientists led by Dr. David
Jenkins at the University of Toronto. In an effort to rethink dietary guidelines
for diabetics, which are based on an intricate system of "exchanges," Jenkins
and his colleagues charted how quickly various foods affect blood sugar levels.
The basic idea of the Glycemic Index has been embraced by many diabetes
organizations around the world.
The American Diabetes Association, however, has not yet endorsed glycemic
indexing. Its refusal to do so raises questions about its practical importance.
Specifically, the ADA believes that the differences in rates of digestion ranked
by the Glycemic Index are not sufficient to warrant changes in the diet. The ADA
also holds that these individual differences fade even further once different
foods are eaten together, at meals.
The range of Glycemic Index numbers are derived by comparing the rate of a
given food's digestion to that a food known to be rapidly digested. The
reference food (different methods use either pure glucose or white bread) is
assigned a Glycemic Index of 100, and the tested food is charted against this
Foods with a high Glycemic Index (70 and above) are those that break down
quickly and cause a spike in blood sugar levels. Foods with a low Glycemic Index
(55 and below) break down more slowly and steadily, providing a sustained supply
Popular notions regarding the rates of absorption of "simple" and "complex"
carbohydrates are refuted by a glance at the Glycemic Index tables. For years,
it was thought that sugary foods like candy and ice cream – composed of simple
carbohydrates – would be absorbed immediately. Similarly, it was believed that
starchier foods like bread and potatoes provided steady, long-term energy. But
these assumptions were made solely by studying the chemistry of the foods in
question. In the body, they act quite differently: Most sugary foods actually
cause very small changes in blood sugar levels, while many starchy foods – white
bread and potatoes in particular – cause sharp spikes.
These are some of the important subtleties and contradictions ignored by
authors of fad diets. By urging a sweeping ban on all carbohydrates, these books
display only a passing familiarity with a nutritional concept whose real-world
applications remain to be seen.
RETURN TO COMMON DENOMINATORS
RETURN TO PROTEIN POWER REVIEW
Weight Loss and the Glycemic Index: The Jury's Still Out
Ranking the digestion rates of various foods may prove an important reference
for diabetics and endurance athletes. Proponents of the Glycemic Index also
argue for its potential as a weight-loss tool.
Researchers behind the G.I. believe it is possible – even inevitable – to
lose weight and keep it off by consuming a diet composed primarily of foods that
rank low on the Glycemic Index. Foods that are slow to be converted into blood
sugar, they say, satisfy the appetite without piling on excess calories. In
addition, most low-G.I. foods contain only small amounts of fat.
It is this last assertion to which the American Diabetes Association takes
particular exception. ADA points out that fats slow digestion, so several foods
containing a high fat content, like chocolate and peanuts, end up scoring low on
the Glycemic Index. It's possible, they say, that in seeking a diet exclusively
defined by the Glycemic Index, an individual may put themselves at higher risk
for heart attack and stroke.
At this writing, there is not enough data to gauge its particular
effectiveness as a long-term weight-management strategy. Only a few clinical
weight-loss trials have yet been performed utilizing the Glycemic Index directly
and exclusively. Until many more trials come in, the usefulness of the G.I. as a
tool for permanent weight control must remain in question.
It should be noted, however, that the weight-management strategy espoused by
researchers who helped develop the G.I. in no way resembles the low-carb,
high-protein plan of fad diets. Most of the foods with low G.I.s , in fact, are
fruits, vegetables, grains and beans, so the diet espoused by Index researchers
looks quite different from the meat-, milk- and cheese-based plans found on the
bestsellers lists today.
Fad Diets and "Food Combining:"
Two of the diet plans reviewed by AICR take this misreading even further and
feature the mysterious practice of "proper food combining."
Both Judy Mazel's New Beverly Hills Diet and Suzanne Somers' Get Skinny on
Fabulous Food offer sternly worded cautions against certain combinations of
foods. Mazel espouses several theories about the mechanics of digestion that are
scientifically incorrect. Somers misinterpretation of the digestive process
leads her to the assertion that certain digestive enzymes "cancel each other
out," which "leads to fatness."
The Glycemic Index itself is nothing more than a means to gauge the relative
rates of digestion of certain foods. It does not contain, nor does it suggest,
any particular theory regarding the body's enzymatic activity. Neither does it
speak to the order in which foods can or should be eaten.
Keeping Things in Proportion for Overall Health
All of the major health organizations and agencies agree on one thing: A diet
high in vegetables, fruits, grains and beans and low in fat is essential to
avoiding chronic disease like cancer, heart disease and stroke.
AICR's Dietary and Health Guidelines call for consuming five or more servings of vegetables and fruit
each day and seven or more servings of whole grains, beans and tubers. Eating so
many servings of plant-based foods cuts down on foods of animal origin – which
the guidelines encourage you to limit.
Following these guidelines leads to healthy proportions on your plate.
Vegetables, fruits, beans and whole grains, all good sources of carbohydrates,
may take up to two-thirds of the space. Animal sources of protein and fat will
be minimal. Instead of cookies, cakes and ice cream – all made with animal fats
– fresh fruit in the summer and fresh, frozen or canned fruit in the winter can
be a common dessert.
The guidelines also call for daily physical exercise to become part of the
"manner of living." Regular physical activity is as much a part of overall
health and disease resistance as a healthy, nutritious diet.
Most people who make the change from a typical high-fat, sedentary American
lifestyle to one which follows these guidelines will slowly, safely lose weight.
For those already following these or similar guidelines who feel the need to
shed some pounds, the method is simple: Maintain the same nutrient proportions
on you plate, slightly decrease portion size, and slightly increase
Portion Control and Serving Sizes
Portion size is a concept that most fad diets do not address. Many call for
the elimination of whole categories of macronutrients but ignore this basic
nutritional concept. In fact, to lose weight without jeopardizing health, most
people should maintain the standard proportion of macronutrients (more
carbohydrates from plant-based foods, less protein and fat from animal-based
foods.) At the same time, they should increase daily exercise levels and
decrease portion sizes.
In general, all Americans need to be aware of portion size, even those not
expressly looking to lose weight. Researchers say that Americans routinely
underestimate how many calories they consume each day by as much as 25 percent.
Busy lifestyles mean countless distractions, and we're turning into a nation
that eats on the run, at our desks, or in front of the television. Individual
portions are difficult to gauge when our attention is divided between a large
carton of take-out Chinese and the six o'clock news.
At the same time, fast-food chains compete for our business by inflating
their serving sizes. Modestly sized bagels and muffins have all but disappeared
from American cafes, replaced creations three or four times larger. Restaurants
are not far behind, using larger plates laden with more food to assure customers
they're getting their money's worth.
Of course, these trends are merely symptoms; how much food we do or do not
eat is ultimately up to us. We've simply forgotten when to say when, and so lost
sight of a fundamental concept of everyday nutrition: the serving size.
It's on the label of every food package in your house. It's the basic unit of
measure used by dietitians and health organizations across the U.S. It lies at
the center of every discussion of balanced diets and weight management, but few
of us have a clear idea how much food a "serving size" actually represents.
RETURN TO BEVERLY HILLS DIET REVIEW
Serving Size -- What it Means
The American Institute for Cancer Research recommends eating five or more
servings of fruits and vegetables each day, as well as more than seven servings
of grains, legumes, and tubers.
To put serving sizes in perspective, look over the list of examples below.
Serving sizes are much smaller than most Americans realize.
According the USDA, 1 serving equals:
- 1 slice of whole-grain bread
- 1/2 cup of cooked rice or pasta
- 3-4 small crackers
- 1 small pancake or waffle
- 2 medium-sized cookies
- 1/2 cup cooked or raw vegetables
- 1 cup (4 leaves) lettuce
- 1 small baked potato
- 3/4 cup vegetable juice
- 1 medium apple
- 1/2 grapefruit or mango
- 1/2 cup berries
- 1 cup yogurt or milk
- 1 1/2 ounces of cheddar cheese
- 1 chicken breast
- 1 medium pork chop
- 1/4 pound hamburger patty
The USDA list, helpful as it is, is only one way to get a handle on portions.
In 1993 the Food and Drug Administration redesigned food labels to make it
easier to gauge serving sizes – and thus calories, fat, protein and nutrients.
In addition, they ordered that serving sizes must be clearly stated and
consistent for all foods in a given product line. The redesigned "Nutrition
Facts" labels appear on most every packaged food product made in the United
There is a small but important difference between the serving sizes
determined by the USDA and those that appear on food labels. The USDA serving
sizes are units of measure that can be used to help balance the overall diet.
Those on "Nutrition Facts" food labels are intended to convey information about
the specific packaged food in question. Fat, cholesterol, sodium, carbohydrate,
protein, vitamins and minerals are calculated for a "typical portion," but keep
in mind that the amount of that portion is not a recommendation, it is, once
again, merely a unit of measure.
FDA regulations leave the food makers a little wiggle room here, and
consumers need to stay alert. Next time you're in the supermarket, compare the
serving sizes on the labels of a regular ice cream and a low-fat ice cream.
You'll likely discover that the serving sizes for low-fat items are slightly
Lists and food labels are excellent sources of information for proper portion
control, but the most important way to manage how much you're taking in is to
develop an eye for serving sizes. Gaining the knack is easier than it sounds; it
doesn't mean breaking out the measuring cups and spoons every time you prepare a
meal or dine out. AICR recommends two quick ways to become conversant with this
important nutritional concept.
Rules of Thumb
The key is to translate the abstract information represented by the serving
size into something visual that's easily remembered. So instead of trying to
memorize lists of ounce, cup and tablespoon equivalents, simply relate the
serving sizes of various foods to familiar physical objects. Here are some
tried-and-true "rules of thumb."
|A SINGLE SERVING OF …
||IS ABOUT THE SIZE OF …|
||Palm of Hand|
||1 Scoop of Ice Cream|
||Deck of Cards|
|2 Tbs. Butter, Margarine,Peanut Butter,
||Thumb (joint to tip)|
|Snacks (Pretzels, Chips)
||Tennis Ball |
||1 Pair of
The "Eyeball" Method
The single best way to determine the amount of food in a given serving,
however, is to consult the Nutrition Facts label and measure it out. Of course,
measuring every food at each meal is not a particularly practical or enjoyable
option, so AICR recommends taking a day to "eyeball" your servings, once and for
Check the label, and fill a measuring cup with the appropriately sized
portion of vegetables, or chicken, or rice, or snacks. Now empty it onto a
plate, and take a good look. How much of the plate is covered? What, exactly,
does one serving of pasta look like? Meat? Sauce?
Even if you do this only once, in those few seconds you'll arm yourself with
information vital to achieving your weight-management goals. By refocusing
attention on an often-overlooked variable in the dieting equation, this method
provides a simple and effective reference point. If you've been eating more than
you realize, the calories and fat grams steadily add up; sooner or later, the
pounds follow. Even if you're not trying to lose weight, taking a moment to see
how many servings of cereal you actually eat each morning could help you
structure your daily intake.
Now That You Know
Once you develop a sense for servings, you'll find controlling your weight
and balancing your diet become easier. You might still load up on your favorite
foods once in a while, but you'll be fully aware that you are doing so, and
that's the key. Paying attention to portions means eliminating the kind of
"unconscious" eating that has helped lead to America's current weight crisis.
Here are some ways to put your newly developed powers of portion control into
- Use smaller dishes at meals.
- Avoid serving food "family style." Serve up plates with appropriate
portions in the kitchen, and don't go back for seconds.
- Put away any leftovers quickly, in separate, portion-controlled
amounts. This makes it harder to sneak extra large helpings later on.
- Never eat out of the bag or carton.
- Ask for half or smaller portions. (Don't worry if it doesn't seem
cost-effective – it's worth it.)
- Eyeball your appropriate portion, set the rest aside, and ask for a
doggie bag right away. Servings are so big at many restaurants that you
may wind up with lunch for two days.
- At buffets, do a little reconnaissance. Walk the length of the buffet
table from the desserts to the appetizers, to know your options. Select
only those foods that truly appeal, and keep the rules of thumb in mind.
If, for example, you want to try several different kinds of fish, make
sure to keep the amounts small enough so that, together, they still fit
inside a checkbook-sized serving.
- If you have dessert, share. (Remember that many restaurant desserts
look better than they taste.)
At the supermarket:
- Beware "mini-snacks" – tiny crackers, cookies, pretzels. Most people
end up eating more than they realize, and the calories add up.
- Choose foods packaged in individual serving sizes. (Again, the extra
money you spend is worth the calories you are likely to save.)
- If you're the type who eats ice cream out of the carton, pick up ice
cream sandwiches or other individual size servings.