Researchers have suggested that pyruvate enhances exercise performance and reduces body weight and body fat, possibly by increasing lipolysis and energy expenditure [ 6 , , ]. Efficacy : Only a few studies have examined the effects of pyruvate supplementation in humans.
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Although some of these studies suggest that pyruvate decreases body weight and body fat, others do not. At the end of the trial, the pyruvate group had significant decreases in body weight mean loss of 1. In the placebo group, these measurements did not change significantly compared to baseline.
However, a double-blind, placebo-controlled trial in 23 overweight women mean BMI The authors of a systematic review and meta-analysis of 6 randomized controlled trials in a total of participants concluded that 5—30 g pyruvate for 3—6 weeks reduces body weight by a mean of 0. However, the authors noted that the methodological quality of all trials is weak, preventing them from drawing firm conclusions.
Safety : The safety of pyruvate has not been rigorously studied. Additional research is needed to better understand the safety and possible side effects of this compound. Raspberry ketone is the primary aroma compound found in red raspberries Rubus idaeus , and it is added to some foods as a flavoring agent [ 16 , ].
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In vitro and animal studies suggest that raspberry ketone might help prevent weight gain by increasing fatty acid oxidation, suppressing lipid accumulation, and inhibiting pancreatic lipase activity [ 16 ]. Although it has been touted on the Internet and national television as an effective way to burn fat, little evidence exists to support this claim.
Efficacy : In mice fed a high-fat diet, raspberry ketone supplementation reduced food intake and body weight compared to the same diet without raspberry ketone [ ]. Only one randomized controlled trial has examined the effects of a dietary supplement containing raspberry ketone on weight loss. This product contained 2, mg of a proprietary blend of raspberry ketone, caffeine, bitter orange, ginger, garlic, cayenne, L-theanine, and pepper extract along with B- vitamins and chromium.
During the 8-week study, participants followed a calorie-restricted diet approximately calories less per day than estimated needs and engaged in moderate exercise 60 minutes 3 days per week. However, 25 of the 70 participants dropped out of the study, and results were reported for only the 45 participants who completed the study i. Furthermore, the product contained many ingredients in addition to raspberry ketone, making it impossible to determine the effects of raspberry ketone alone.
Safety : Typical diets provide only a few mg of raspberry ketones a day. Doses contained in dietary supplements typically range from to 1, mg, and the safety of such doses has never been evaluated in humans [ ]. However, additional research on raspberry ketone is needed to better understand its safety and side effects. Vitamin D, which is fat soluble, is present in a few foods, such as fatty fish, cheese, egg yolks, and vitamin D-fortified milk.
It is also available in many dietary supplements, and humans synthesize it naturally when their skin is exposed to sunlight. Vitamin D promotes calcium absorption in the gastrointestinal tract and is needed for proper bone growth and remodeling [ 56 ]. Observational studies indicate that greater body weights are associated with lower vitamin D status, and obese individuals frequently have marginal or deficient circulating levels of vitamin D [ ].
Nevertheless, the association between vitamin D and obesity raises the question of whether increasing vitamin D concentrations might reduce body weight [ , ]. Efficacy : Despite the association between low vitamin D levels and obesity, scientific evidence does not support a cause-and-effect relationship. The authors commented that the cause of this finding might have been stored vitamin D in body fat and skeletal muscle that was released during weight loss. However, according to a meta-analysis of 12 vitamin D supplementation trials including 5 in which body composition measurements were primary outcomes , vitamin D supplements without calorie restriction did not affect body weight or fat mass compared to placebo [ ].
Overall, the available research suggests that consuming higher amounts of vitamin D or taking vitamin D supplements does not promote weight loss. Vitamin D toxicity can cause anorexia, weight loss, polyuria, and heart arrhythmias. It can also raise calcium blood levels, which can cause vascular and tissue calcification. White kidney bean or bean pod Phaseolus vulgaris is a legume that is native to Mexico, Central America, and South America and is cultivated worldwide [ ].
Phaseolus vulgaris extract is an ingredient in some weight-loss dietary supplements marketed as carbohydrate- or starch-absorption "blockers. Phaseolus vulgaris might also act as an appetite suppressant [ , ].
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Efficacy : The effect of Phaseolus vulgaris on weight loss and body fat has been examined in a few clinical trials, which had inconsistent results. After 30 days, those receiving Phaseolus vulgaris extract lost significantly more weight mean weight loss 2. Those in the Phaseolus vulgaris group also experienced a significantly greater reduction in fat mass, adipose tissue thickness, and waist—hip—thigh circumference.
However, the authors noted that the quality of the trials included in their review was poor, making it impossible to draw firm conclusions.
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After the publication of that review, a week clinical trial in overweight and obese men and women showed that Phaseolus vulgaris modestly yet significantly reduced body weight and body fat [ ]. Compared to those taking placebo, those receiving Phaseolus vulgaris lost significantly more body weight mean loss of 2.
Safety : Reported adverse effects for Phaseolus vulgaris are minor and include headaches, soft stools, flatulence, and constipation [ ]. No serious adverse effects of Phaseolus vulgaris have been reported in clinical trials, but no trials have lasted longer than 13 weeks. Yohimbe Pausinystalia yohimbe, Pausinystalia johimbe is a West African evergreen tree.
Yohimbine has hyperadrenergic physiological effects because it acts as an alpha-2 receptor antagonist [ 6 , ]. Yohimbe extract is an ingredient in some dietary supplements that are promoted for libido enhancement, body building, and weight loss [ ], but it is used primarily as a traditional remedy for sexual dysfunction in men. The authors of a review of yohimbe concluded that no conclusive evidence indicates that yohimbe affects body weight or body mass [ ]. The author of a review of yohimbe reached similar conclusions, noting that results from small human trials of yohimbine for weight loss are contradictory and the evidence base is insufficient to support a weight loss claim for this compound [ ].
Safety : Yohimbe can be dangerous. Taking 20 to 40 mg of yohimbine has been reported to increase blood pressure slightly, whereas doses of mg or higher can cause headaches, hypertension, anxiety, agitation, tachycardia, myocardial infarction, cardiac failure, and death [ 43 , , , , ]. More recently, dietary supplements containing yohimbe accounted for 1, self-reports to U. Although yohimbe is generally well tolerated at low doses [ ], no safe dose has been established for it. Yohimbe should only be used under medical supervision because of its potential to produce serious adverse effects [ ].
The active compounds, which are in the plant's stem and account for about 1. In the s, ephedra—frequently combined with caffeine—was a popular ingredient in dietary supplements sold for weight loss and to enhance athletic performance. The FDA no longer permits the use of ephedra in dietary supplements because of safety concerns that are detailed below, but information is provided here in response to continued interest in this ingredient. Efficacy : Ephedrine acts as a stimulant in the central nervous system [ , ], and it might increase thermogenesis and act as an appetite suppressant [ ].
The authors of a meta- analysis that included 20 clinical trials concluded that ephedrine and ephedra are modestly effective for short-term weight loss 6 months or less , but no studies have assessed their long-term effects [ ]. Safety : While ephedra was available as a dietary supplement ingredient in the United States, its use with or without caffeine was associated with numerous reported adverse effects, including nausea, vomiting, psychiatric symptoms such as anxiety and mood change , hypertension, palpitations, stroke, seizures, heart attack, and death [ , ].
Although these reported adverse effects could not be linked with certainty to the use of ephedra-containing dietary supplements, the FDA deemed the safety concerns serious enough to prohibit the sale of dietary supplements containing ephedrine alkaloids in [ ]. As a result of this ruling, manufacturers are no longer permitted to sell dietary supplements containing ephedrine alkaloids in the United States.
Like all dietary supplements, weight-loss supplements can have side effects and might interact with prescription and over-the-counter medications. In some cases, the active constituents of botanical or other ingredients promoted for weight loss are unknown or uncharacterized [ 29 ]. Furthermore, many weight-loss supplements contain multiple ingredients that have not been adequately tested in combination with one another.
Pittler and Ernst noted that for ingredients lacking convincing evidence of effectiveness, "even minor adverse events shift the delicate risk-benefits balance against their use" [ 6 ]. People need to talk with their healthcare providers about the use of weight-loss dietary supplements to understand what is known—and not known—about these products. At best, products with claims like these do not live up to them, and even worse, they could be dangerous.
Between January and December , dietary supplements were subject to a Class I recall by the FDA, indicating a reasonable probability that use of or exposure to these products would cause serious adverse health consequences. In most cases, the recall was due to the presence of undeclared drug ingredients. In , the FDA issued 36 public notifications warning consumers not to purchase specific weight-loss products because they contained a hidden drug ingredient—often sibutramine, a weight-loss medication that was withdrawn from the U.
A product represented as a dietary supplement that contains one or more drug ingredients, whether or not these ingredients are declared on the label, is considered an unapproved drug and is therefore subject to enforcement action by the FDA. The FDA maintains a webpage listing public notifications about tainted weight-loss products. Some ingredients in weight-loss dietary supplements can interact with certain medications. For example, glucomannan and guar gum might decrease the absorption of many drugs that are taken orally [ , ].
Glucomannan has been reported to lower blood glucose levels [ ] and, therefore, could interact with diabetes medications [ ]. Chitosan might potentiate the anticoagulant effects of warfarin [ ]. Green tea could interact with chemotherapy drugs [ , ]. Garcinia cambogia was associated with serotonin toxicity in a patient taking the supplement together with two selective serotonin reuptake inhibitor medications [ ].
Other ingredients, such as caffeine and bitter orange, could have an additive effect if taken with other stimulants. Bitter orange has also been shown to inhibit CYP3A4 activity, leading to increased blood levels of certain drugs, such as cyclosporine and saquinavir [ 43 ].
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These are just a few examples of interactions between ingredients of weight-loss dietary supplements and medications. Individuals taking dietary supplements and medications on a regular basis should discuss their use with their healthcare provider. As this fact sheet shows, the evidence supporting the use of dietary supplements to reduce body weight and stimulate weight loss is inconclusive and unconvincing, and the cost of these products can be considerable [ 6 , 14 , 29 , 41 ]. The best way to lose weight and keep it off is to follow a sensible approach that incorporates a healthy eating plan, reduced caloric intake, and moderate physical activity under the guidance of a heath care provider.
For some individuals with a high BMI who have additional health risks, physicians may prescribe adjunctive treatments, including FDA- approved prescription medications or bariatric surgery, in addition to lifestyle modifications [ 7 ].