More than two-third of adults and almost one-third of children and adolescents in the United States are overweight or obese [ 12 ]. Health experts agree that making lifestyle changes—including following a healthy eating pattern, reducing caloric intake, and engaging in physical activity—is the basis for achieving long-term weight loss [ ]. But because making diet and lifestyle changes can be difficult, many people turn to dietary supplements promoted for weight loss in the hope that these products will help them more easily achieve their weight-loss goals.
Dietary supplements promoted for weight loss encompass a wide variety of products and come in a variety of forms, including capsules, tablets, liquids, powders, and bars [ 11 ]. Manufacturers market these products with various claims, including that these products reduce macronutrient absorption, appetite, body fat, and weight and increase metabolism and thermogenesis.
Weight-loss products can contain dozens of ingredients, and some contain more than 90 [ 11 ]. Common ingredients in these supplements include botanicals herbs and other plant componentsseratonin and weight loss, dietary fiber, caffeine, and minerals. In its report on dietary supplements for weight loss, the U. Government Accountability Office concluded that "little is known about whether weight loss supplements are effective, but some supplements have been associated with the potential for physical harm" [ 12 ].
So it is important to consider what is known—and not known—about each ingredient in any dietary supplement before using it. This is especially important for those who have medical conditions, including high blood pressure, diabetes, and liver or heart disease.
Yet, according to a large national survey, less than one-third of U. Food and Drug Administration FDA regulates dietary supplements, including those promoted for weight loss [ 13 ]. Like other dietary supplements, weight-loss supplements differ from over-the-counter or prescription medications in that the FDA does not classify them as drugs.
Unlike drugs, dietary supplements do not require premarket review or approval by the FDA. Supplement manufacturers are responsible for determining that their products are safe and seratonin and weight loss label claims are truthful and not misleading. If the FDA finds a supplement to be unsafe, seratonin and weight loss, it may take enforcement action to remove the product from the market or ask the manufacturer to recall the product.
The FDA and the Federal Trade Commission can also take regulatory actions against manufacturers that make unsubstantiated weight-loss claims about their products. The FDA does not permit dietary supplements to contain pharmaceutical ingredients, and manufacturers may not promote dietary supplements to diagnose, treat, cure, or prevent any disease [ 13 ].
What You Need to Know. Weight-loss dietary supplements contain a wide variety of ingredients. Not surprisingly, the amount of scientific information available on these ingredients varies considerably.
In some cases, evidence of their purported benefits consists of limited data from animal and laboratory studies, seratonin and weight loss, rather than data from human clinical trials. Complicating the interpretation of many study results is the fact that most weight-loss dietary supplements contain multiple ingredients, making it difficult to isolate the effects of each ingredient and predict the effects of the combination.
Evidence may exist for just one of the ingredients in a finished seratonin and weight loss, and no evidence may be available for an ingredient when it is combined with other ingredients.
Studies might also use different and sometimes inappropriate assessment techniques to measure the effectiveness of a given treatment. All of these factors can make it difficult to compare the results of one study with those of another.
Table 1 briefly summarizes the findings discussed in more detail in this fact sheet radiation treatment and cancer the safety and efficacy of the most common ingredients of weight-loss dietary supplements.
These ingredients are listed anti hormones discussed in the table and text in alphabetical order.
Dosage information is provided when it is available, seratonin and weight loss. However, because ingredients might not be standardized and many products contain proprietary blends of ingredients, the active compounds and their amounts might not be comparable among products [ 15 ]. African mango, or Irvingia gabonensisseratonin and weight loss, is a fruit-bearing tree that is native to western and central Africa [ 16 ]. Irvingia gabonensis seed kernel extract has been proposed to promote weight loss by inhibiting adipogenesis, as demonstrated relationship between thyroid and female hormones vitro [ 17 ].
Studies have examined the effects of Irvingia gabonensis on weight loss to only a limited extent in humans. Participants who received the extract had significantly lower body weight, body fat, and waist circumference at the end of the trial than those taking a placebo. This trial, along with two others, was included in a systematic review whose authors reported that Irvingia gabonensis extract causes statistically significant reductions in body weight and waist circumference [ 19 ].
The authors noted, however, that the trials included in the review used different study methodologies, small samples, short intervention periods, and varying daily doses of Irvingia gabonensis extract mg to 3, mg ; in addition, the trials were all conducted by the same authors.
Additional trials with larger samples and diverse populations are needed to determine whether Irvingia gabonensis extract is effective for weight loss [ 19 ]. Irvingia gabonensis extract appears to be well tolerated. Most reported adverse effects are mild, including headache, difficulty sleeping, flatulence and gas [ 19 ]. However, seratonin and weight loss, Irvingia gabonensis has been associated with renal failure in a patient with chronic kidney disease [ 21 ]. Beta-glucans are glucose polysaccharides found in bacteria, yeasts, fungi, and cereal grains such as oats and barley.
As soluble dietary fibers, beta-glucans are proposed to increase satiety and gastrointestinal transit time and to slow glucose absorption [ 16 ]. Consumption of beta-glucans from barley has been shown to reduce energy intake and appetite in humans [ 22 ].
Several studies have investigated the effects of beta-glucans on blood lipids, blood pressure, and insulin resistance, with weight seratonin and weight loss as a secondary outcome.
In one of these studies, 66 overweight women followed a low-calorie diet designed to produce a 0. At the end of the trial, all groups lost weight and had a smaller waist circumference, but there were no significant differences between groups. Beta-glucans appear to be well tolerated. Reported adverse effects include increased flatulence, but not changes in stool consistency, stool frequency, or bloating [ 24 ]. Bitter orange is the common name for the botanical Citrus aurantium.
As alpha-adrenergic agonists, synephrine alkaloids can mimic the action of epinephrine and norepinephrine. However, the extent to which bitter orange and synephrine cause similar cardiovascular and central-nervous-system effects to epinephrine and norepinephrine e. Studies suggest that bitter orange zepp antenna plans energy expenditure and lipolysis and that it acts as a mild appetite suppressant [ 2527 ].
Although synephrine has some structural similarities to ephedrine, it has different pharmacological properties [ 2730 ]. Several small human studies have examined whether bitter orange is effective for weight loss [ 30 ]. Interpreting the results of these studies is complicated by the fact that bitter orange is almost always combined with other ingredients in weight-loss supplements, seratonin and weight loss.
At the end of the study, participants taking the combination bitter orange product had a significantly greater reduction in percent body fat and fat mass and a greater increase in basal metabolic rate than those in the placebo and control groups. Participants in all groups lost weight, but the authors did not report whether the mean reduction in body weight in the treatment group 1. The peak rise in resting metabolic rate at baseline was significantly higher in participants taking the herbal supplement than those in the placebo group, but the difference was not significant at the end of the 8-week study.
Participants taking the herbal supplement had a significant increase in mean seratonin and weight loss weight 1, seratonin and weight loss. However, this increase in body weight did not significantly affect body fat and lean tissue levels or waist circumference. The authors noted seratonin and weight loss the weight gain might have occurred by chance because the trial was insufficiently powered to detect this small difference, seratonin and weight loss. The authors of a review of 23 small human clinical studies involving a total of participants concluded that synephrine increases resting metabolic rate and energy expenditure [ 30 ].
According to all seratonin and weight loss these reviews, longer-term clinical trials with rigorous designs and large samples are needed to determine the value of bitter orange for weight loss.
Products containing bitter orange may have significant safety concerns. Reported adverse effects include chest pain, headache, anxiety, elevated seratonin and weight loss rate, musculoskeletal complaints, seratonin and weight loss, ventricular fibrillation, seratonin and weight loss, ischemic stroke, myocardial infarction, and death [ 3435 ].
However, many of the products with these effects contain seratonin and weight loss herbal ingredients, and the role of bitter orange seratonin and weight loss these adverse effects cannot be isolated.
Some studies indicate that bitter orange and synephrine—as bitter orange extract or pure synephrine—raise blood pressure and heart rate, but other studies show that they do not have these effects .
Some researchers have suggested that synephrine might not act directly as a cardiovascular stimulant [ 273739 ]. Instead, caffeine, other stimulants in multicomponent formulations, and other constituents of bitter orange or adulterants such as m-synephrine, which is not naturally present seratonin and weight loss bitter orange might be responsible for its observed effects.
Green tea and other forms of tea also contain caffeine see section on green tea. Some weight-loss supplement labels do not declare the amount of caffeine in the product and only list the herbal ingredients. As a result, consumers might not be aware that the presence of certain herbs means that a product contains caffeine and possibly other stimulants [ 41 ].
Caffeine is a methylxanthine that stimulates the central nervous system, heart, and skeletal muscles, seratonin and weight loss. It also increases seratonin and weight loss and colonic activity and acts as a diuretic [ 4243 ]. Caffeine has a half-life of about 6 hours; blood levels increase within 15—45 minutes of consumption, and they peak at around 60 minutes [ 44 ].
Caffeine increases thermogenesis in a linear, dose-dependent fashion in humans [ 45 ]. A mg dose of caffeine, for example, increased energy expenditure by a mean of 9.
Caffeine might also contribute to weight loss by increasing fat oxidation through sympathetic activation of the central nervous system and by increasing fluid loss [ 4145 ], seratonin and weight loss.
Habitual use of caffeine however, leads to caffeine tolerance and a diminishment of these effects [ 4143 ]. Caffeine increases energy expenditure and fat oxidation [ 44 ]. However, the extent to which these effects affect weight loss is less clear, seratonin and weight loss, partly because clinical trials examining the effects of caffeine on weight loss have all been short and have used combination products.
After 6 months, those in the treatment group lost significantly more weight mean weight loss 5. A product containing caffeine plus glucosyl hesperidin G-hesperidin, a flavonone glycoside found mainly in citrus fruits reduced abdominal fat and BMI in a clinical trial in Japan [ 47 ]. In this study, 75 healthy, overweight men and women BMI 24—30 received one of five treatments daily for 12 weeks while maintaining their regular lifestyle and eating habits.
The five treatments were placebo and four formulations of 0, 25, 50, or 75 mg caffeine plus mg G-hesperidin. The 75 mg caffeine plus G-hesperidin significantly reduced BMI by a mean of 0. The 50 or 75 mg caffeine plus G-hesperidin also significantly reduced abdominal fat compared to placebo, whereas the G-hesperidin alone or with only 25 mg caffeine did not significantly affect BMI or abdominal fat.
These findings indicate that the higher doses of caffeine might be responsible for the observed effects. At the end of the study, seratonin and weight loss, participants taking the herbal product lost a mean of 5.
Data from a year prospective observational study provide some insight into the long-term association between caffeine intake and body weight [ 49 ].
On average, participants gained some weight during the type ii diabetes and risk, but men who increased their caffeine intake during the 12 years of follow-up gained a mean of 0. For women, the corresponding mean difference in weight gain was 0.
However, further research is needed to confirm this finding. For comparison, an 8-ounce cup of brewed coffee contains about 85— mg caffeine. Caffeine can cause sleep disturbances and feelings of nervousness, jitteriness, and shakiness. Combining caffeine with other stimulants, such as bitter orange and ephedrine, can potentiate these adverse effects.
Calcium is an essential mineral that is stored in the bones and teeth, where it supports their structure and function. Calcium is required for vascular contraction and vasodilation, muscle function, nerve transmission, intracellular signaling, and hormonal secretion [ 56 ].