16 The Encyclopedia of Addictive Drugs
The first diet drug to receive scientific endorsement was thyroid hormone.
Its use for this purpose began in the 1890s on the theory that it would boost
a person’s metabolism and thereby promote faster use of calories. The same
theory made dinitrophenol a standard diet drug before World War II. Al-
though it boosted metabolic rate, it also boosted rates of cataracts and of harm
to the peripheral nervous system (which involves the functioning of various
organs and muscles). For those reasons the drug was abandoned. In the 1930s
amphetamines became available and quickly became a popular diet aid de-
spite their potential for abuse.
Many stimulants suppress appetite, and some are used as medicines to help
people lose weight. Those medicines are called “anorectics.” Their stimulant
effects may be lower than drugs in other classes but can still have potential
for abuse and addiction. For that reason, many anorectics are scheduled sub-
stances.
Such drugs are casually described as appetite suppressants, but not all pro-
mote weight loss in that way. For instance, some may affect the way food is
absorbed in the body; some increase a person’s rate of metabolism so the
person burns more calories; some make a person more physically energetic.
Question has even been raised about whether a stimulant’s anorectic action
simply comes from elevating the mood of depressed people and thereby re-
ducing their need to gain comfort from eating. Mechanisms by which anorec-
tics work are poorly understood.
Indeed, whether they work at all is uncertain. Compared to placebos, most
studies show additional weight loss among persons taking anorectics to be
measurable but barely noticeable; some studies show anorectics to be no more
effective than placebos. In experiments where anorectics work well, skeptics
wonder if results come from factors other than the drug, such as rapport
between physician and patient, belief that the substance would work, or even
from basics such as controls on food intake during the experiment. Scientists
directing one study of anorectics concluded that sensations of appetite sup-
pression were so subtle that a user could miss them unless the person was
trying to be aware of them.^9 The effectiveness of an anorectic declines as weeks
go by, through development of tolerance. A telling exception to development
of tolerance is methylcellulose, an unscheduled substance used to increase
bulk of consumed food and thereby increase the physical feeling of fullness.
The substance has no psychological effect, and no tolerance develops. Meth-
ylcellulose is also among the least effective dieting aids.
Abusers of stimulant anorectics exhibit symptoms similar to those found
among abusers of amphetamines, from skin rash to psychosis. Some persons
using anorectics properly under medical supervision experience muscle pain
and cramps, weariness, peevishness, depression, difficulty in thinking. That
group of symptoms is the same as those undergone by persons trying to cope
with lack of food regardless of drug use, a coincidence raising question about
whether some undesired effects attributed to anorectics are simply undesired
effects of being hungry.
A harsh fact about anorectics is that weight lost while using them tends to
return if a person stops taking the drugs (and generally they are intended for
short-term use only). Behavioral therapy teaches people how to change their