Is there any Magic?
Millions of Americans are overweight, and the latest studies tell us that more and more people are becoming overweight every year (Kuczmarski, Flegal, Campbell, & Johnson, 1994). Being overweight is a risk factor for heart disease, stroke, diabetes, and several kinds of cancer (Department of Health and Human Services, 1988).
Weight loss is big business, and many companies compete
for our attention and our money through advertising. Many claims are made
and it is hard for people to know what is possible, what is reasonable,
what is an exaggeration, and what is an outright lie. Outrageous advertising
claims harm the public by creating unrealistic expectations that cannot
be realized. If you think it is possible to lose a pound a day on a weight
loss program and instead you lose a pound a week, you may become discouraged
and give up on trying to follow reasonable plans that lead to gradual,
modest weight loss. Much frustration comes from unrealistic expectations
about how quickly and how easily one can lose weight.
There is no magic involved in losing weight. Your
fat cells are like a gas tank on a car in that they store fuel until you
need it. When a gas tank is full, you cannot add any more gas. However,
our body fat stores continue to expand as long as we continue to take in
more energy than we burn. To lose body fat, you must burn more energy that
you eat so that your body has to draw upon the fuel stored in fat cells.
The only way to lose weight is to increase the amount of fuel you burn,
decrease the amount you consume, or do both at the same time. The rate
at which you can lose weight is limited by how fast the body burns energy.
The average overweight woman (180 pounds) burns about
2000 calories a day (Thompson & Manore, 1996; Heska, Feld, & Yang,
1993). A pound of body fat contains 3,500 calories. To lose a pound of
body fat, you have to burn 3,500 calories more than you eat. To lose a
pound a day (or 30 pounds in 30 days), simple arithmetic shows that they
only way this is possible is for the average overweight woman to stop eating
and to start doing 1,500 calories a day of extra exercise. To burn this
many extra calories, the 180 pound woman would have to ride a bicycle 5
hours a day every day for a month while completely fasting (Ainsworth,
Haskell, Leon, Jacobs, Montoye, Sallis, & Paffenbarger, 1993) .
The problem of losing 30 pounds in 30 days is made
more complicated by the fact that your need for calories is goes down as
you lose weight (Kinney, 1995). After losing 30 pounds, our average woman
would require about 250 fewer calories per day to maintain her weight (assuming
she has given up the five hours of bike riding). Another way to look at
it is to say that to continue losing a pound a day, this woman would need
to add an extra 50 minutes to her daily bike ride by the end of a month
to make up for the decline in calories her body burns.
Is there a pill, or an herb, or a mineral, or a diet
counselor that will make you stop eating and start riding a bicycle 5 hours
a day? Could you keep this up for a month? The answers are no and obviously
not. After one 5-hour bike ride you would be so hungry (not matter what
pill or herbal supplement you are taking) that wild horses could not keep
you from eating. Besides, why not continue to eat your regular amount of
food and be happy to lose 10-12 pounds in a month. Sure it would take 3-4
months to drop 30 pounds, but think how strong you would be and how good
you would feel at the end. Think how weak you would be and how terrible
you would feel if you tried to stick with the 30 pounds in 30 days weight
Unfortunately, wanting something to be true does
not make it true. It is simply not possible for the average person to lose
a pound of day even by completely fasting. In 1993, the American Medical
Association reviewed the results of hundreds of weight loss studies (AMA,
1993). Using very low calorie diets (800 calories per day) in conjunction
with a comprehensive program, they concluded that people could lose an
average of 40 pounds in 3-4 months, However, these diets require medical
supervision to be safe. They are also expensive and have been estimated
to cost participants about $55.00 for each pound lost (Rubin, 1994). These
programs do not work for everyone since drop-out rates are usually 30%
or more (Shovic, Adams, & Dubitzky, 1993). When people follow a 1200
calorie a day diet, the average weight loss is about a pound per week (Brownell
& Wadden, 1993).
In a recent study in the Journal of the American
Dietetic Association (Skender, M.L., Goodrick, G.K., & Del Junco, D.J.,
1996), 127 adults were assigned to diet only, exercise only, or diet plus
exercise. After two years, the diet only group weighed on the average 2
pounds more than they did when they started, even though they initially
lost an average of 15 pounds. The exercise only group initially lost only
6 pounds, but at the end of two years they still weighed an average of
five pounds less than when they started. The diet plus exercise group did
the best, losing 20 pounds right away and were still 6 pounds less than
when they started two years later.
When very intensive behavior modification programs
have been combined with agressive long-term follow-up, people have been
able to keep weight off for over a year. Peri, McAllister, Gange, and Nezu
(1992) were able to achieve and sustain average weight losses of 20-30
pounds when participants received long-term aggressive behavior modification
combined with moderate caloric restriction and regular aerobic exercise.
The reputable commercial weight loss programs like nutri-system and Weight
Watchers provide behavior modification and long-term counseling. Many of
the products being sold over the internet provide no counseling or behavior
modification and typically involve using a combination of nutritional supplements.
Christakis and Miller-Kovach (1996) conducted a follow-up study with 1,200 members of weight watchers who reached their weight loss goals and became lifetime members. These, of course, are only the most successful participants. The average weight loss among these participants was 29 pounds. Sixty seven percent had maintained their weight within five pounds of their goal. After five years, however, only 37 percent will still within five pounds of their weight goal.
These studies show that the best available programs
that provide behavior modification, nutrition education, and encouragement
to exercise rarely result in weight losses of more than 20-30 pounds. The
participants in these studies often took over a year to lose this much
weight, and then many of them had problems maintaining their weight losses
for more than a year or two.
It is important to compare the claims made by various
weight loss schemes to these data. If long term behavior modification programs
result in 20-30 pounds lost after a year, a nutritional supplement with
no attempt to change eating behavior or increase exercise is not likely
to result in 30 pounds of weight loss in a month. Margolis (1995) discusses
various weight loss products and programs that are unlikely to work. Programs
that promise that you can eat all you want, or that you can lose weight
without changing eating or exercise habits are unlikely to work.
Psychology DepartmentThe Health Psychology Home Page is produced and maintained by David Schlundt, PhD.
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