Assessing the science behind weight loss supplements
When it comes to
weight, America has a problem. Nearly 27 percent of Americans report that they
are obese (based on self-reported weight and
height, and defined as a body mass index (BMI) greater than 30), according to data
from 2009 (the most recent year available).
Although that number may not seem significant, consider
this: Obesity is a risk factor for a number of diseases, including metabolic
and cardiovascular diseases, such as Type 2 diabetes, dyslipidemia, atherosclerosis, hypertension and stroke; and for
cancer, including cancers of the colon, breast, kidney and digestive tract.
It's also a risk factor for nonlife threatening diseases, including arthritis,
sleep apnea, gallstones and gout; and for affective disorders, including low self-esteem.
With such a laundry list, experts say it is in the public's interest for Americans
to lose that excess weight. But the only proven way to do so is to move more,
eat less and eat better. In a society where food often is plentiful and where many
have sedentary lifestyles, this may be easier said than done.
This is where weight loss pills -- pharmaceutical or
over-the-counter dietary supplements -- enter the fray. Our buyer's guide
outlines the types, science, efficacy and issues involving the pills, but they
all have one thing is common: None of them work on their own, you must diet and
exercise as well. There is no magic bullet. All of these are merely tools to help
advance weight loss efforts.
Unfortunately, there are plenty of companies who want to prey upon
people's desire to both lose weight and for the quick fix. They advertise
supplements with claims that have not been verified or tested by a reputable
independent organization. Manufacturers don't have to seek FDA approval before
putting dietary supplements on the market.
Because diet pills come and go, and because there are some who question
whether regulation of dietary supplements is effective, it is impossible for us
to choose a Best Reviewed diet pill. Instead, we have assembled the science and
safety profiles for each type and gathered specifics on their ingredients.
These include pharmaceuticals, nutrient blockers (fat and carb blockers), fat
burners, insulin regulators, appetite suppressants and body composition
changers.
We turned to the scientific community and government agencies
for information. We consulted with publications from the CDC, U.S. Food and Drug Administration, the Natural Medicines
Comprehensive Database and medical journals. We
also relied on reports from major newspapers, such as The New York Times, Los
Angeles Times and The Wall Street Journal, because we found that they presented
a fair and balanced review of weight-loss drugs. Website and magazine articles,
such as ones from Redbook, WebMD.com and Health, cover these topics briefly,
but we found that their coverage is largely superficial.
Types of Diet Pills Fat Burners/Thermogenics
Is it worth living in a stressful state to lose weight?
Just the name "fat burner" as a dietary supplement category elicits
the image of your body becoming an inferno to melt away the inches of
fat surrounding your belly and thighs, but that isn't the case. Many of
these supplements, also known as thermogenics, are meant to increase
your metabolism, or energy expenditure, by stimulating your sympathetic
nervous system. Best known for controlling our fight or flight reaction,
it prepares us to react to a stressful situation by preparing the body
for action -- increasing heart rate, blood pressure, blood flow to the
brain, body heat production (aka thermogenesis), basal metabolic rate
(aka the number of calories our body burns at rest) and more.
Furthermore, the sympathetic nervous system regulates the body's process
of breaking down fat (aka fat oxidation) for energy, which may have an
important role in the regulation of total body fat, as well as working
every hour of every day to keep the body at homeostasis, or its usual
equilibrium.
Thermogenics
stimulate the sympathetic nervous system to burn more energy while at
rest and are known as stimulants. One of the most well-known is
caffeine, and it is the active ingredient in many of the diet
supplements listed in this category; for instance, green tea and guarana
(
Paullinia cupana). Another commonly known thermogenic is ma huang, also known as
Ephedra sinica.
It was banned in 2005 by the Food and Drug Administration (FDA) because
of serious side effects or unintended consequences of its use. Ephedra
has been replaced by synephrine -- a compound similar to ephedra -- that
serves as the main active substance in bitter orange (
Citrus aurantium). Other thermogenic supplements include capsaicin,
Cirsium oligophyllum, and yohimbine (
Pausinystalia yohimbe).
Some of these thermogenic diet pills have been shown to produce a small
amount of weight loss, but the question you should be asking is: Are
they worth the risk?
For example, the combination of ephedra and caffeine is known to
cause weight loss, but it's also known to cause insomnia, nervousness,
tremors, increased blood pressure, irregular heart rates and, more
seriously, strokes, heart attacks and death. According to American
Family Physician, between 1997 and 1999 alone, there were 87 reports
made to the FDA program MedWatch about ephedra, of which 23 occurred in
patients with no previous health problems who were taking the
recommended dose. Ten of the 87 events reported while using ephedra led
to death, and 13 led to permanent disability. The use of ephedra helped
patients lose an additional 2 pounds per month.
Ephedra has been banned, but questions remain about whether its
cousin, synephrine is any safer. Many diet pills have multiple
ingredients, and you may end up taking more than one thermogenic. This
can have dangerous consequences. For more on the efficacy and risks of
each thermogenic, please see below.
Caffeine
What is it? Caffeine is a chemical compound found in multiple plants,
namely those used to make coffee, chocolate and tea. According to
ConsumerGuide.com, about 90 percent of Americans consume caffeine every
day via sodas, energy drinks, some headache medications and diet pills.
Caffeine is the main active ingredient in guarana (
Paullinia cupana) and one of the active ingredients in green tea (
Camellia sinensis). According to the Natural Medicines Comprehensive Database (NMCD), caffeine is found in 859 products on the market.
Does it work? Caffeine has most often been studied in combination with other thermogenics such as ma huang, better known as
Ephedra sinica,
guarana and yerba maté. Although it might be effective in producing
weight loss in the short term, according to clinical studies, more
research is needed. That's largely because the most effective
combination -- ephedra and caffeine -- is no longer available. Caffeine
is also known to be an efficient diuretic, and the loss of water weight
can look like weight loss when taken in the short term. For each
milligram of caffeine consumed, approximately 1.17 milliliters (mL) of
water is excreted through the urine.
Is caffeine safe? Caffeine is safe when used in small amounts;
however when taken in large doses it can cause tremors, delirium,
agitation, chest pain, an irregular heart rhythm and an increase in
heart rate and breathe. At doses of 150 to 200 milligrams (mg) per
kilogram (kg) of body weight, about 10,000 to 14,000 mg for an
average-weight adult, caffeine can be fatal. (By comparison, a large
brewed coffee from Starbucks contains 320 mg of caffeine.) Multiple
ingredients in diet pills can contain caffeine, including green tea,
guarana and yerba mate, and you can also get caffeine from other
sources, such as coffee and energy drinks. Caffeine can interact with
various other supplements and medications, especially other stimulants.
Speak to your healthcare provider before starting a supplement that
contains caffeine.
Green tea (camellia sinensis
What is it? Green tea is made from
Camellia sinensis plant
leaves. The main active ingredients in green tea are believed to be the
antioxidant epigallocatechin gallate (EGCG) and caffeine. Most often
consumed as a beverage, green tea is also available in pill form as an
extract. According to the Natural Medicines Comprehensive Database
(NMCD), there are 2,998 products on the market that contain green tea.
The amounts of EGCG and caffeine can vary in each product because
growing conditions, leaf age and storage can have an effect. Some
extracts will state what percentage EGCG or caffeine is present, but
typically a cup of green tea will contain between 80 and 100 milligrams
(mg) of antioxidants and between 10 and 80 mg of caffeine.
Does it work? It's unclear, but green tea extract may help weight
loss efforts in certain circumstances. Some preliminary studies (human
and animal) showed that green tea increased thermogenesis and the basal
metabolic rate (BMR); clinical studies have produced conflicting
results. Some studies have shown no weight loss when using green tea
compared to a placebo, but others have shown a moderate reduction in
weight, body mass index (BMI) and body fat when taking green tea in
conjunction with exercise. In addition, it appears that green tea when
taken in conjunction with caffeine can reduce weight, BMI and waist
circumference more effectively than when caffeine is taken alone.
However, the studies that have been conducted are small, and more
research needs to be done before a definitive answer can be given as to
green tea's efficacy.
Is green tea safe? Mostly. Studies show that there are minimal
adverse events, or unintended consequences of consuming green tea in
moderate amounts -- less than six cups of tea per day for less than six
months. Reported side effects are mild and include vomiting, abdominal
bloating, gas and diarrhea. However because green tea contains caffeine,
taking high doses for extended periods can be dangerous, causing
insomnia, agitation, tremors, and restlessness. With higher doses, one
possibly could experience irregular heart rhythms and heart failure.
Therefore, it is important to keep track of the other sources of
caffeine in your diet to prevent an overdose -- approximately 10 to 14
grams (g) for an average adult. Fourteen cases of liver damage while
using green tea extract have been reported. In most of these cases, the
liver function returned to normal when the product was no longer
consumed, but in one case a liver transplant was required. Green tea can
also interact with various supplements and medications, especially
those that are also stimulants. Before taking green tea as a supplement,
speak with your health care provider.
Guarana (Paullinia cupana)
What is it? Guarana is made from the seeds of the Brazilian plant
Paullinia cupana,
also known as Brazilian cocoa. It contains 3 to 5 percent caffeine, and
this is the main ingredient believed to confer the weight loss
benefits. Guarana is also a popular ingredient in soft drinks,
especially in South America.
Does it work? Probably not -- at least on its own. Preliminary
studies of diet pills that contain guarana along with other ingredients
suggest that it may be effective at producing modest weight loss, about 6
pounds in two months, but it is unclear whether these results are due
to guarana or one of the other ingredients. More research is needed.
Is guarana safe? Mostly. Guarana's high concentration of caffeine is
the root of any side effects. Like caffeine, mild consumption causes
minimal side effects, but larger doses can cause insomnia, nervousness,
elevated heart rate, tremors, irregular heart rhythms and chest pain. At
doses of 150 to 200 milligrams (mg) per kilogram (kg) of body weight,
about 10 to 14 grams (g) for an average adult, caffeine can be fatal. Be
aware of what other dietary supplements, foods and drinks you are
consuming that contain caffeine. Guarana can interact with any other
herbal supplement or medication that is considered a stimulant as well
as other medications. Speak to your healthcare provider first before
starting a supplement that contains guarana.
Synephrine
What is it? Synephrine mimics the effects of the sympathetic nervous
system, making it a sympathomimetic agent. It is chemically similar to
phenylephrine, a medication used to decrease congestion and increase
blood pressure. Synephrine is found in several products, including the
ingredient bitter orange (
Citrus aurantium).
Does it work? It may, but evidence as to whether synephrine is
effective at producing weight loss is conflicting. Synephrine has most
often been studied in conjunction with bitter orange and caffeine. While
one study suggests that it might help reduce weight when combined with
diet and exercise, another study shows no significant weight loss with
its use. More research is needed.
Is synephrine safe? Probably not, because side effects include high
blood pressure, increased heart rate, irregular heart rhythm, heart
attack, stroke and sudden death. Because of its similarities to ephedra,
many experts and medical professionals say that synephrine should be
banned as well. Synephrine can have significant interactions with other
herbal supplements and medications that have stimulant effects. If you
do choose to use a product with synephrine, definitely speak to your
healthcare provider beforehand. As an aside, the National Collegiate
Athletic Association (NCAA) has banned the use of this substance.
Bitter orange (citrus aurantium)
What is it? The bitter orange (
Citrus aurantium) is also known
as the Seville orange or the sour orange. The fruit and peel are used
for weight loss, and their main active ingredient is synephrine, a
chemical that stimulates the sympathetic nervous system. For more
information, please see our section on
Synephrine.
Does it work? It could be effective, but only time will tell. Four
small studies show weight loss of between 4 and 6 pounds over several
months, and some studies have shown that bitter orange has no effect on
weight loss. Additional studies have been done on diet pills with
multiple ingredients including bitter orange. While these studies have
had mixed results, it is unclear whether the results are due to bitter
orange or to any of the other ingredients. More research is required.
Is bitter orange safe? Probably not, given that the main active
ingredient in bitter orange is synephrine -- whose side effects include
high blood pressure, increased heart rate, irregular heart rhythm, heart
attack, stroke and sudden death. Because of its similarities to
ephedra, many believe that bitter orange also should be banned. It can
have significant interactions with other herbal supplements and
medications that have stimulant effects. Before you use it, speak to
your healthcare provider. As with synephrine, the NCAA has also banned
the use of bitter orange by its athletes.
Capsaicin
What is it? Capsaicin, also known as capsicum, is the chemical
responsible for making peppers spicy. Its pungent taste can produce a
burning sensation on the tongue. It stimulates the sympathetic nervous
system, thereby increasing thermogenesis, or heat production, according
to animal and human research. According to the Natural Medicines
Comprehensive Database (NMCD), there are 1,516 products on the market
containing capsaicin.
Does it work? Possibly. Clinical studies in humans have shown an
increase in energy expenditure following the intake of capsaicin after a
meal. In addition, some studies have shown a reduction in body fat and
weight following the use of capsaicin. However, researchers discovered
that patients had difficulty taking the full dosage because of its
pungency, making it ineffective for long-term use. Further research is
needed.
Is capsaicin safe? Yes, to a point. When used at doses typically
found in food, there is minimal safety concern; however long-term use,
especially of high doses (more than 120 mg a day), may be linked to
kidney, liver and gastrointestinal damage. Side effects, or unintended
consequences, that can occur at lower doses include abdominal
discomfort, gas, nausea, heartburn, diarrhea, and sweating. There are
few interactions with medications, but theoretically capsaicin can
increase the effects of blood thinners such as Coumadin (warfarin),
Lovenox (enoxaparin) and Plavix (clopidogrel). Before using capsaicin at
higher doses, speak to your healthcare provider.
Cirsium oligophyllum
What is it?
Cirsium oligophyllum is a type of thistle
commonly found in eastern Asia and central Japan. Research is relatively
minimal, but it is believed that cirsium activates the sympathetic
nervous system like other thermogenics, thereby promoting the breakdown
of fat cells.
Does it work? The jury is just starting to deliberate on this
ingredient. Only one scientific study could be located, and this study
was conducted on rats. While the study showed promising results for the
use of cirsium in weight loss and reducing body fat, it is difficult to
say that these same results can be expected in humans. Further research
is necessary.
Is cirsium oligophyllum safe? It is unknown at this time. Such
minimal research has been done into cirsium that there is not enough
data on adverse events, or unintended consequences, of its use.
Yohimbine (pausinystalia yohimbe)
What is it? Yohimbine (
pausinystalia yohimbe) is a
stimulant derived from the ground bark of a tall evergreen native to
Central Africa. It is most commonly used as an aphrodisiac. There are
338 products containing yohimbe on the market, according to the Natural
Medicines Comprehensive Database (NMCD), though at least half of them
are in the sexual aid category.
Does it work? There isn't enough evidence to say yes or no, because
only three randomized clinical trials have been conducted. Their results
are conflicting, and more research is required to determine whether
yohimbine is a viable weight loss aid.
Is yohimbine safe? It's questionable. Yohimbine has been associated
with some serious adverse effects, including agitation, irregular heart
rhythms, heart attacks and seizure. Yohimbine can interact with other
herbal and prescription stimulants and has been known to have an
additive effect to monoamine oxidase inhibitors (MAOIs). Do not take
yohimbine unless you are under a doctor's supervision.
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