Conditions:
Weight Loss
Related Terms
•
Obesity
Principal Proposed Treatments
•
Chromium, Pyruvate, Fiber, 5-HTP (5-Hydroxytryptophan)
Other Proposed Treatments
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Calcium, Vitamin D, HCA, Caffeine-Ephedrine, Vitamin C, Evening Primrose Oil, CLA, MCTs, Spirulina, Green Tea, Diacylglycerol, L-Carnitine, DHEA, Combination Herb/Supplement Therapies, Many Others
Losing weight can be a lifelong challenge. Researchers who study obesity consider it a chronic health condition that must be managed much like high blood pressure or high cholesterol. That means there's no easy cure.
Losing just 5 to 10% of your total weight can lower blood pressure, raise "good" cholesterol (high-density lipoprotein, or HDL), prevent diabetes, improve blood sugar control if you already have diabetes, and reduce the risk of developing arthritis of the knee.1–6
In most cases, obesity is due to lifestyle factors such as diet and exercise. However, studies show that diet alone only sometimes reduces weight, and exercise alone seldom offers more than modest benefits. But the combination of improved diet and regular exercise is the best way to lose weight and keep it off.
Weight-loss drugs have had a patchy safety record. Prescription amphetamines for reducing appetite proved dangerously addictive, and other diet drug combinations such as fenfluramine-phentermine (fen-phen) have had dangerous side effects. New drugs may be safer and more effective.
Principal Proposed Treatments for Weight Loss
Chromium
Chromium is a mineral the body needs in only small amounts, but it's important to human nutrition.
Although it has principally been studied for improving blood sugar control in people with diabetes, chromium has also been tried for reducing body fat. The results of studies have been mixed. However, whether or not it actually assists weight loss, chromium may offer heart-healthy benefits for overweight individuals. Both of these potential benefits involve chromium's effects on insulin. Before we can explain how chromium may help, we need to provide some background information on how the body controls its blood sugar levels.
The body needs a constant level of glucose (sugar) in the blood. When you digest a carbohydrate meal, glucose levels rise. Protein meals have the same effect, although to a lesser extent. Your body responds by secreting insulin. Insulin causes the cells of your body to absorb glucose out of the blood, thereby reducing circulating blood sugar.
Once cells have taken in glucose, they can burn it for energy or convert it to a storage form. Liver and muscle cells can store a limited amount of glucose as glycogen. Fat cells can convert unlimited amounts of glucose into energy stored as fat.
The process also goes the opposite way. When your body has used up the food from its last meal, blood glucose levels drop. Just as the body doesn't like it when glucose levels are too high, low glucose levels also cause problems. So your body applies its control mechanisms to raise blood sugar levels. It does so by reducing its output of insulin, and also by raising levels of another hormone called glucagon. The net effect is that energy storage depots are mobilized. Glycogen is converted back into glucose. In addition, fat cells release their contents into the bloodstream to supply an alternate energy source.
To summarize: High insulin levels build fat, while low insulin levels break down fat.
Based on this push-pull effect, if you want to lose weight you'd probably rather keep your insulin levels low.
Dieting is the most obvious method of reducing insulin. When you don't take in enough calories to supply your body's daily needs, insulin levels fall and your body breaks down fat cells. Exercising is another method: By increasing your body's energy requirements, exercise causes insulin levels to fall and fat cells to break down.
But it's difficult to consistently use more energy than you take in. Hunger takes over, and you start wanting to eat. If there were some way to trigger fat breakdown without going hungry, it would make weight loss much easier.
There's another important connection between insulin and weight to consider. Individuals who weigh too much often develop insulin resistance. In this condition, certain cells of the body become less sensitive to insulin. The body senses this, and increases insulin production until it overcomes the resistance. It is possible that fat cells respond to these increased levels of insulin by storing even more fat.
This is the point where chromium comes in.Chromium is thought to improve the body's responsiveness to insulin. Combining this fact with the insulin–weight connections just described, some researchers have proposed that chromium may assist in weight loss.
Their main argument goes like this: Chromium increases insulin sensitivity. This causes levels of insulin to fall.88 With reduced amounts of insulin in the blood, fat cells are less inclined to store fat, and weight loss may become easier.
In addition, there is some evidence that chromium partially blocks insulin's effects on fat cells, interfering with its fat-building effect.89 This too could assist weight loss.
However, there are several flaws in these arguments. For example, even very small amounts of insulin in the blood effectively suppress fat breakdown.90–94
Another problem is that during insulin resistance, fat cells also appear to become resistant to insulin.95–98 Insulin resistance, in other words, might be a natural method of keeping the lid on weight gain. Chromium supplements might have the undesired effect of increasing the ability of fat cells to respond to insulin, helping them store fat better!
However, theory only takes one so far. It is more important to review the results of studies in which people were given chromium supplements to reduce their weight.
What is the Scientific Evidence for Chromium?
Weight Loss In one study, 154 individuals were given either placebo or 200 or 400 mcg of chromium picolinate daily.7 Participants were not advised to follow any particular diet. Over a period of 72 days, individuals taking chromium experienced significantly greater weight loss than those not taking chromium, over 2-1/2 pounds versus about 1/4 pound. Interestingly, individuals taking chromium actually gained lean body mass, so the loss of fatty tissue was even more dramatic: over 4 pounds versus less than 1/2 pound.
Another double-blind study by the same researcher, however, failed to demonstrate benefit. In this 3-month trial, 122 moderately overweight individuals attempting to lose weight were given either placebo or 400 mcg of chromium daily.8 No statistically significant differences were seen between groups. Researchers had to resort to fairly complicated statistical maneuvers in an attempt to show some benefit.
Seven other double-blind, placebo-controlled studies also failed to find evidence of benefit with chromium picolinate.9–14,99 One possible explanation for these discrepancies could be that chromium's effects are relatively slight and can only be demonstrated in larger trials.
Heart-Healthy Effects for Overweight Individuals Whether or not it improves weight loss, chromium might offer health benefits for overweight individuals.
As described above, overweight individuals frequently become resistant to their own insulin. The body responds by releasing more and more insulin. Sooner or later, however, this compensating mechanism reaches a limit, and cells simply find it hard to absorb glucose from the bloodstream. The result is a rise in blood sugar levels.
Even when mild, this condition dramatically increases risk of heart disease.100–106 The risk goes up still further when insulin resistance becomes severe and develops into type 2 (adult-onset) diabetes.
Weight loss almost always improves insulin resistance. It appears that chromium supplements may also help.
In a double-blind, placebo-controlled study, 180 people with type 2 diabetes were given placebo, 200 mcg of chromium picolinate daily, or 1,000 mcg of chromium picolinate daily. Individuals taking 1,000 mcg showed marked improvements in blood sugar levels. Lesser but still significant benefits were also seen in the 200-mcg group, but not in the placebo group.107
Many other studies have been performed on chromium supplementation in both diabetes and glucose intolerance. The results have been mixed, perhaps because most of these studies were relatively small.108–114 Nonetheless, overall, chromium is a promising treatment for improving mild glucose intolerance. For this reason, overweight individuals might benefit from supplemental chromium, even if it doesn't help them lose weight.
For more information, including dosage and safety issues, see the full chromium article.
Pyruvate
Pyruvate supplies the body with pyruvic acid, a natural compound that plays important roles in the manufacture and use of energy. Theoretically, taking pyruvate might increase the body's metabolism, particularly of fat. However, the evidence that it works is limited to small studies. Some of these trials also used dihydroxyacetone, a chemical closely related to pyruvate.
What Is the Scientific Evidence for Pyruvate?
Weight Reduction Several small studies enrolling a total of about 150 individuals have found evidence that pyruvate or DHAP (a combination of pyruvate and dihydroxyacetone) can aid weight loss and/or improve body composition.21–25,115
For example, in a 6-week double-blind placebo-controlled trial, 51 individuals were given either pyruvate (6 g daily), placebo, or no treatment.115 All participated in an exercise program. In the treated group, significant decreases in fat mass (2.1 kilograms) and percentage body fat (2.6%) were seen, along with a significant increase in muscle mass (1.5 kilograms). No significant changes were seen in the placebo or nontreatment groups.
Another placebo-controlled study (blinding not stated) used a much higher dose of pyruvate, 22 to 44 g daily depending on total calorie intake.21 In this trial, 34 slightly overweight individuals were put on a mildly weight-reducing diet for 4 weeks. Subsequently, half were given a liquid dietary supplement containing pyruvate. Over the course of 6 weeks, individuals in the pyruvate group lost a small amount of weight (about 1-1/2 pounds) while those in the placebo group did not lose weight. Most of the weight loss came from fat.
Another interesting placebo-controlled study evaluated the effects of DHAP when individuals who had previously lost weight increased their calorie intake.23 Seventeen severely overweight women were put on a restricted diet as inpatients for 3 weeks, during which time they lost approximately 17 pounds. They were then given a high-calorie diet. Approximately half of the women also received 15 g of pyruvate and 75 g of dihydroxyacetone daily. The results found that after 3 weeks of this weight-gaining diet, individuals receiving the supplements gained only about 4 pounds, as compared to about 6 pounds in the placebo group. Close evaluation showed that pyruvate specifically blocked regain of fat weight.
While all these studies are intriguing, we really need large studies (100 participants or more) to establish the benefits of pyruvate for weight loss.
For more information, including dosage and safety issues, see the full pyruvate article.
Fiber
Dietary fiber is important to many intestinal tract functions including digestion and waste excretion. It also appears to have a mild cholesterol-lowering effect and might help reduce the risk of some kinds of cancer (although the current evidence is a bit contradictory).
Fiber might also be useful for losing weight. It's thought to work in a simple way: by filling the stomach and causing a feeling of fullness, while providing little to no calories. Fiber might also interfere with absorption of fat.
There are two kinds of fiber: soluble fiber, which swells up and holds water, and insoluble fiber, which does not. Soluble fiber is found in psyllium seed (sold as a laxative), apples, and oat bran. Most other plant-based foods contain insoluble fiber.
Fiber supplements may contain a variety of soluble or insoluble fibers from grain, citrus, vegetable, and even shellfish sources.
What Is the Scientific Evidence for Fiber Supplements?
Several double-blind, placebo-controlled studies have evaluated fiber supplements as a weight-loss aid. The results have been somewhat inconsistent, but in general it appears that some forms of fiber may assist weight loss.
In one of the largest studies, 97 mildly overweight women on a strict low-calorie diet were given either placebo or an insoluble fiber (type not stated) 3 times daily for 11 weeks.26 Women given fiber lost almost 11 pounds compared to about 7 pounds in the placebo group. Participants using the fiber reported less hunger.
Researchers weren't finished with their subjects! For an additional 16 weeks, their diet was changed to one that supplied more calories. As expected, participants regained some weight during this period. Nonetheless, by the end of the 16 weeks, individuals taking fiber were still 8 pounds lighter than at the beginning of the study, while those taking placebo were only 6 pounds lighter.
Another study evaluated whether the benefits of dietary fiber endure over 6 months of dieting. This double-blind trial of 52 overweight individuals found that use of an insoluble, dietary fiber product (made from beet, barley, and citrus) almost doubled the degree of weight loss as compared to placebo.27 Once more, participants using the fiber supplement reported less hunger.
Two other double-blind placebo-controlled studies evaluated a similar insoluble fiber product.28,116 The first enrolled 60 moderately overweight women and put them on a 1,400-calorie diet along with placebo or fiber for a period of 2 months. The other study was similar, but enrolled only 45 women and followed them for 3 months. The results of both studies again showed improved weight loss and reduced feelings of hunger in the treated groups. However, a 24-week study of 53 moderately overweight individuals found no difference in effect between placebo and 4 g of insoluble fiber daily.117
Glucomannan, a source of soluble dietary fiber from the tubers of Amorphophallus konjac, has also been tried for weight loss, with positive results in adults. In a double-blind placebo-controlled trial of 20 overweight individuals, researchers found that use of glucomannan significantly improved weight loss over an 8-week period.29 Benefits were also seen in a double-blind placebo-controlled trial of 28 overweight individuals who had just experienced a heart attack.30 However, another trial studied the effectiveness of glucomannan as a weight-loss agent in 60 overweight children, and found no benefit.31
An 8-week double-blind placebo-controlled trial of 59 overweight individuals evaluated the effects of chitosan, a mostly insoluble fiber from crustaceans, taken at a dose of 1.5 g prior to each of the two biggest meals of the day.32 No special diets were assigned. The results showed that, on average, participants in the placebo group gained more than 3 pounds over the course of the study, while those taking chitosan lost more than 2 pounds.
In contrast, an 8-week double-blind placebo-controlled trial of 51 women found that use of chitosan at a dose of 1,200 mg twice daily failed to cause any weight loss.118
Similarly, in a 28-day double-blind trial of 30 overweight individuals, chitosan taken at a dose of 1 g twice daily did not induce weight loss.33 The shorter duration, lower dosage, and smaller number of participants in this trial may account for the lack of results.
A few trials have only evaluated effects on hunger and satiety rather than weight loss. One study found that the soluble fiber pectin (from apples) reduces hunger sensations.34 Another found that the soluble fiber guar gum slows stomach emptying and increases the sensation of fullness.35 However, a more recent study evaluated the effects of guar gum in 25 women undergoing a weight-loss program, and found no influence on hunger.36
Dosage
The optimum dose of fiber and the proper time to take it have not been determined.
In the first three studies described previously, insoluble fiber supplements were given 20 to 30 minutes prior to each meal at a dose of about 2.3 g, along with a large glass of water. For additional dosage information, see the full articles on glucomannan and chitosan.
Safety Issues
Fiber supplements must be taken with water; otherwise they may block the digestive tract. Even when used properly, mild gastrointestinal side effects such as gas and bloating may occur.
As a kind of positive side effect, fiber supplements may reduce cholesterol and blood pressure levels.37–41
For other important safety issues, see the full articles on chitosan and glucomannan.
5-HTP
Serotonin is an important chemical in the brain. Although there's much we don't know about how it works, serotonin is thought to play a major role in numerous conditions, including depression and anxiety. Drugs in the Prozac family increase serotonin levels, an action believed to play a major role in how they work.
Serotonin is also thought to influence appetite and eating behavior. Fenfluramine, the infamous "fen" part of "fen-phen," acts somewhat similarly to Prozac. When combined with phentermine ("phen"), it was, in some people's opinion, the most effective weight-loss agent ever discovered. Unfortunately, fenfluramine had to be taken off the market because it caused damage to the valves of the heart.
Other drugs that raise serotonin have also been tried for weight loss. This fact has led to such acronyms as "Proz-phen" and "Zo-phen," for phentermine combinations involving Prozac and Zoloft.
The supplement 5-HTP (5-hydroxytryptophan) is another option that's drawn considerable interest since the demise of fenfluramine.
The body manufactures serotonin from 5-HTP. Therefore, it is reasonable to suppose that taking supplemental 5-HTP will enhance serotonin production. Indeed, preliminary evidence suggests that 5-HTP has antidepressant properties,42,43 perhaps to the same extent as drugs in the Prozac family.
Several studies suggest that 5-HTP might aid weight loss as well.
What Is the Scientific Evidence for 5-HTP (5-Hydroxytryptophan)?
A total of four small double-blind placebo-controlled clinical trials have examined whether 5-HTP can aid weight loss.
The first of these, a double-blind crossover study, found that use of 5-HTP (at a daily dose of 8 mg per kilogram body weight) reduced caloric intake despite the fact that the 19 participants made no conscious effort to eat less.44 Participants given placebo consumed about 2,300 calories per day, while those taking 5-HTP ate only 1,800 calories daily. Use of 5-HTP appeared to lead to a significantly enhanced sense of satiety after eating. Over the course of 5 weeks, women taking 5-HTP effortlessly lost over 3 pounds.
A follow-up study by the same research group enrolled 20 overweight women who were trying to lose weight.45 Participants received either 5-HTP (900 mg per day) or placebo for two consecutive 6-week periods. During the first period, there was no dietary restriction, while during the second participants were encouraged to follow a defined diet expected to lead to weight loss.
Participants receiving placebo did not lose weight during either period. However, those receiving 5-HTP lost about 2% of their initial body weight during the no-diet period, and an additional 3% while on the diet. Thus, a woman with an initial weight of 170 pounds lost about 3-1/2 pounds after 6 weeks of using 5-HTP without dieting, and another 5 pounds while dieting. Once again, participants taking 5-HTP experienced quicker satiety.
Similar benefits were seen in a double-blind study of 14 overweight women given 900 mg of 5-HTP daily.46
Finally, a double-blind placebo-controlled study of 20 overweight individuals with adult-onset diabetes found that use of 5-HTP (750 mg per day) without intentional dieting resulted in about a 4-1/2 pound weight loss over a 2-week period.47 Use of 5-HTP reduced carbohydrate intake by 75% and fat intake to a lesser extent.
Unfortunately, all these studies were performed by a single research group. In science, results aren't considered valid until they are independently replicated by different researchers. In addition, all these studies were small in size. For these reasons, further research is necessary before we can consider 5-HTP a proven weight-loss agent.
For more information, including dosage and safety issues, see the full 5-HTP article.
Other Proposed Treatments for Weight Loss
Calcium and Vitamin D Supplements
Rapid weight loss in overweight postmenopausal women appears to accelerate osteoporosis slightly.51 For this reason, taking calcium and vitamin D supplements—always a good idea—may be especially appropriate here. Interestingly, there is some evidence that calcium supplements might also facilitate weight loss to some extent, for reasons that aren't clear.52
Garcinia cambogia
Hydroxycitric acid (HCA), a derivative of citric acid, is found primarily in a small, sweet, purple fruit called Garcinia cambogia, the Malabar tamarind. Although animal and test tube studies as well as one human trial suggest that HCA might encourage weight loss, other studies have found no benefit.53–64,119,121 In an 8-week double-blind placebo-controlled trial of 60 overweight individuals, use of HCA at a dose of 440 mg 3 times daily produced significant weight loss as compared to placebo.119
In contrast, a 12-week double-blind placebo-controlled trial of 135 overweight individuals, who were given either placebo or 500 mg of HCA 3 times daily, found no effect on body weight or fat mass.62 However, this study has been criticized for using a high-fiber diet, which is thought to impair HCA absorption.120
Other small placebo-controlled studies found HCA had no effect on metabolism, appetite, or weight.63,64,121
The bottom line: It is not yet clear whether Garcinia cambogia is an effective treatment for weight loss.
Caffeine and Ephedrine
Caffeine and ephedrine (found in ephedra, an herb also known as ma huang) are central nervous system stimulants. Considerable evidence suggests ephedrine/caffeine combinations can assist in weight loss.65–69, 135
For example, in a double-blind placebo-controlled trial, 180 overweight individuals were placed on a weight-loss diet and given either ephedrine/caffeine (20 mg/200 mg), ephedrine alone (20 mg), caffeine alone (200 mg), or placebo, 3 times daily for 24 weeks.70 The results showed that the ephedrine/caffeine treatment significantly enhanced weight loss, resulting in a loss of more than 36 pounds as compared to only 29 pounds in the placebo group. Neither ephedrine nor caffeine alone produced any benefit. Contrary to some reports, participants did not develop tolerance to the treatment. For the whole 6 months of the trial, the treatment group maintained the same relative weight loss advantage over the placebo group.
We don't know exactly how ephedrine/caffeine works. However, caffeine has actions that cause fat breakdown and enhance metabolism.71 Ephedrine suppresses appetite and increases energy expenditure. The combination appears to produce synergistic effects, with appetite suppression probably the most important overall factor.
Note: These stimulants, especially when combined, affect the heart. Ephedrine/caffeine combinations should only be used under physician supervision. In addition, whole ephedra herb may contain other chemicals that present risk. See the full ephedra article for more information.
Vitamin C
Vitamin C, the single most popular vitamin supplement in the United States, has been tested in hundreds of clinical studies for dozens of illnesses from cancer to colds, and even for weight loss.
Results of two small double-blind placebo-controlled studies suggest that significantly overweight people who take vitamin C supplements may lose some weight,72,73 but larger studies will have to be conducted before these results can be taken as recommendations.
Evening Primrose Oil
Evening primrose is a native American wildflower, named for the late afternoon opening of its delicate flowers. Its seeds are one of the best natural sources of cis-gamma-linolenic acid (GLA), an important member of the essential omega-6 family of fatty acids.
A 12-week double-blind study that enrolled 100 significantly overweight women compared the effectiveness of evening primrose oil to placebo.74 No difference was seen between the groups. However, there was a high dropout rate in this trial (over 25%), which somewhat decreases the meaningfulness of the results. In addition, many participants were known to have "refractory obesity," meaning that they had already failed to respond to other forms of treatment.
Another double-blind trial tested the unusual hypothesis that evening primrose might only work in individuals with a family history of obesity.75 A total of 47 people with a family history of obesity were enrolled in this study. The results showed that use of evening primrose oil produced a small but significant loss of weight. Interestingly, participants whose parents were both obese showed even better response.
Considering the contradictory nature of this evidence, more research is necessary to determine whether evening primrose oil is really useful for weight loss.
Conjugated Linoleic Acid (CLA)
Conjugated linoleic acid (CLA) is a mixture of different isomers, or chemical forms, of linoleic acid. This is an essential fatty acid—a type of fat that your body needs as much as it needs vitamins.
CLA has been proposed as a fat-burning substance, but the evidence that it works is mixed at best.76–79,122,132,134
Medium-Chain Triglycerides (MCTs)
Some evidence suggests that MCT consumption might enhance the body's natural tendency to burn fat.123,124,125 This has led to investigations of MCTs as a weight-loss aid. However, the results of clinical trials thus far have not been impressive.
In a 4-week double-blind placebo-controlled trial, 66 women were put on a very low-carbohydrate diet to induce ketosis.126 Half of the women received a liquid supplement containing ordinary fats; the other half received a similar supplement in which the ordinary fats were replaced by MCTs.
The results indicated that the MCT supplement significantly increased the rate of "fat burning" during the first 2 weeks of the trial and also reduced the loss of muscle mass. However, these benefits declined during the last 2 weeks of the trial, which suggests that the effects of MCTs are temporary.
In other trials, substitution of MCTs for ordinary fats in a standard low-calorie diet failed to enhance weight loss.127,128,131
Other Treatments
Preliminary evidence suggests that a special type of fat known as diacylglycerol may help individuals lose fat, especially fat around the abdomen.80
One double-blind placebo-controlled trial investigated the possible weight-loss effects of spirulina.81 However, while individuals taking 8.4 g of spirulina daily lost weight, the difference between the spirulina group and the placebo group was not statistically significant. Larger and longer studies are needed to establish whether spirulina is indeed an effective treatment for obesity.
A double-blind placebo-controlled trial that enrolled 158 moderately overweight volunteers tested a mixture of chromium, cayenne, inulin (a nondigestible carbohydrate), and phenylalanine (an amino acid), as well as other herbs and nutrients.82 All participants lost weight over the 4-week trial. Those using the supplement lost a bit more weight, but the difference was not mathematically significant. However, a bit of positive news came from close examination of results. Among those taking the supplement, a significantly higher percentage of the weight loss came from fat instead of muscle.
Weight-loss benefits were seen in a double-blind trial of 150 overweight individuals given either placebo or one of two doses of a combination therapy containing chitosan, chromium, and Garcinia cambogia.129 Benefits were also seen in a 45-day double-blind placebo-controlled trial of 44 overweight people that tested a combination product containing yerbe mate, guarana, and damiana.130
A double-blind placebo-controlled study evaluated the effects of a mixture containing Citrus aurantium (bitter orange), caffeine, and St. John's wort.83Citrus aurantium contains various stimulant chemicals related to nasal spray decongestants. The results suggest that this combination might assist weight loss, but the study was so small (23 participants divided into three groups) that the results mean little.
One small double-blind study suggests that use of colostrum by healthy men and women undergoing exercising training may improve body composition as compared to whey protein.133
A rather theoretical study found that two ingredients in green tea may interact to increase metabolism.84
An enormous number of other supplements are marketed for weight loss. Most have little to no evidence behind them, and some have been found ineffective in preliminary studies. For example, certain supplements are said to be lipotropic, meaning that they help your body metabolize fat or slow down the rate at which it's stored. Vitamins
B5 and B6, biotin, choline, inositol, lecithin, and lipoic acid are often placed in this category. However, there is no real evidence that they'll help you lose weight.
Beans partially interfere with the body's ability to digest carbohydrates, which is why they cause flatulence. Based on this, products containing the French white bean Phaseolus vulgaris have recently been widely marketed as carbohydrate-blockers. However, there is no evidence that this treatment (or any other bean) actually aids weight loss.
A number of amino acids are said to reduce hunger, including phenylalanine, tyrosine, methionine, and glutamine. Because the herb kava appears to be helpful for anxiety, it has been proposed as a treatment for mood-related overeating. The antidepressant herb St. John's wort has been recommended with much the same reasoning.
Seaweeds such as kelp, bladderwrack, and sargassi are often added to diet formulas, under the assumption that they will affect the thyroid gland through their iodine content. However, the effect of iodine on thyroid function depends on whether you are iodine deficient. Excess iodine can actually suppress the action of the thyroid. The herb guggul (Commiphora mukul) is often claimed to enhance thyroid function, and for this reason it is often sold as a weight-loss agent. However there is little evidence that it actually affects the thyroid, and a small double-blind trial found it no more effective than placebo for weight loss.85
Numerous herbs and supplements with potential or known effects on insulin are widely added to weight-loss formulas, again, without any evidence that they are effective. These include alfalfa, Anemarrhena asphodeloides, arginine, Azadirachta indica (neem), bilberry leaf, bitter melon (Momordica charantia), Catharanthus roseus, Coccinia indica,Cucumis sativus, Cucurbita ficifolia, Cuminum cyminum (cumin), Euphorbia prostrata, garlic, glucomannan, Guaiacum coulteri, Guazuma ulmifolia, guggul, holy basil (Ocimum sanctum), Lepechinia caulescens, Musa sapientum L. (banana), nopal cactus (Opuntia streptacantha), onion, Psacalium peltatum, pterocarpus, Rhizophora mangle, salt bush, Spinacea oleracea, Tournefortia hirsutissima,Turnera diffusa, and vanadium.
Herbs with laxative or diuretic properties or reputations are also popular in weight-loss formulas, although they are unlikely to produce anything beyond a slight temporary effect. These include barberry, buchu, cascara sagrada bark, cassia powder, cleavers, cornsilk, couchgrass, dandelion root, fig, goldenrod, hydrangea root, juniper berry, peppermint, prune, senna leaf, tamarind, turkey rhubarb root, and uva ursi.
Herbs supposed to "strengthen" the body in general are found in many diet formulas, including ashwagandha, cordyceps, Eleutherococcus, fo-ti, ginseng, maitake, reishi, schisandra, and suma.
Other herbs and supplements sometimes recommended for weight loss for reasons that are unclear include buckthorne, cayenne, chickweed, coenzyme Q10, cranberry, fennel, flax, ginger, ginkgo, gotu kola, grape seed extract, hawthorn, licorice, milk thistle, parsley, passionflower, plantain, white willow, yellow dock, yucca, and zinc.
One small double-blind trial found no benefit with the supplement L-carnitine.86
DHEA has been proposed as a weight loss aid, but the little evidence that is available appears more negative than positive.87
View References
Last reviewed March 2002 by Medical Review Board
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