Most dietary supplements marketed for rapid weight loss, such as acai and hoodia, are ineffective for long-term weight control, and some have serious safety concerns. Researchers have investigated the weight loss potential of a variety of dietary supplements, including green tea extracts, Chinese herbs, and bitter orange extract, but none have been shown to be effective for weight loss, and each has side effects.
Acai berry products have become popular in the United States, where they have been marketed as folk or traditional remedies for weight-loss and anti-aging purposes, but there is no definitive scientific evidence to support these claims.
The Evidence Base
- No high-quality, independent studies have been published about the efficacy of acai supplements in promoting rapid weight loss.
- There is no scientific evidence based on clinical studies to support the use of acai supplements for any health-related purpose.
- In a laboratory study examining the safety profile of an acai-fortified juice found no changes in body weight compared with controls.
- There is little reliable information about the safety of acai as a supplement. It is widely consumed as an edible fruit or as a juice.
- People who are allergic to acai or to plants in the Arecaceae (palm) family should not consume acai.
Overall, only a few small studies of bitter orange have been published, and the evidence is insufficient to support the use of bitter orange (Citrus aurantium) for any health purpose.
The Evidence Base
- The evidence base on the efficacy of bitter orange for weight loss consists of only a few small clinical studies.
- A 2004 systematic review of only one eligible randomized controlled trial of 20 people found no statistically significant benefit for weight loss. Similarly, another 2004 review found little evidence that weight loss products containing bitter orange (Citrus aurantium) are an effective aid to weight loss.
- There have been some reports of fainting, heart attack, and stroke in healthy people after taking bitter orange supplements alone or combined with caffeine. People should avoid taking bitter orange supplements if they have a heart condition or high blood pressure, or if they are taking medications (such as MAO inhibitors), caffeine, or other herbs/supplements that speed up the heart rate.
- Due to lack of safety evidence, pregnant women or nursing mothers should avoid products that contain bitter orange.
- Bitter orange oil used on the skin may increase the risk of sunburn, particularly in light-skinned people.
There is little evidence of ephedra’s effectiveness, except for short-term weight loss. However, in 2004, the FDA banned the U.S. sale of dietary supplements containing ephedra after finding that these supplements had an unreasonable risk of injury or illness—particularly cardiovascular complications—and risk of death.
The Evidence Base
- The evidence base on efficacy and toxicity of ephedra for weight loss consists of several systematic reviews and meta-analyses.
- A 2003 study examining the relative safety of ephedra compared with other herbal products by analyzing phone calls to poison control centers found a higher rate of side effects from ephedra.
- Other studies and systematic reviews have found an increased risk of heart, psychiatric, and gastrointestinal problems, as well as high blood pressure and stroke, with ephedra use.
- In 2004, the FDA banned the U.S. sale of dietary supplements containing ephedra. The FDA found that these supplements had an unreasonable risk of injury or illness—particularly cardiovascular complications—and a risk of death. The ban does not apply to traditional Chinese herbal remedies or to products like herbal teas regulated as conventional foods.
- Between 1995 and 1997, the FDA received more than 900 reports of possible ephedra toxicity. Serious adverse events such as stroke, heart attack, and sudden death were reported in 37 cases.
- Using ephedra may worsen many health conditions such as cardiovascular disease, kidney disease, and diabetes.
- Ephedra may cause seizures in otherwise healthy people as well as in people with seizure disorders.
- Taking ephedra can also result in anxiety, difficulty urinating, dry mouth, headache, heart damage, high blood pressure, irregular heart rhythms, irritation of the stomach, kidney stones, nausea, psychosis, restlessness, sleep problems, and tremors.
- Women who are pregnant or breastfeeding and children should avoid taking ephedra.
- Ephedra use may lead to serious health problems when used with other dietary supplements or medicines.
- Combining ephedra with caffeine increases the risk of potentially serious side effects.
There are not enough reliable data to determine whether green tea can aid in weight loss.
The Evidence Base
The evidence base on efficacy of green tea extracts for weight loss consists of several randomized controlled trials and a Cochrane systematic review.
- A 2012 Cochrane review of 18 randomized controlled trials of at least 12 weeks’ duration in overweight or obese adults found that the loss in weight in adults who had taken a green tea preparation was very small, not statistically significant, and not likely to be clinically important.
- Green tea is safe for most adults when used in moderate amounts.
- There have been some case reports of liver problems in people taking concentrated green tea extracts; however, these problems do not seem to be connected with green tea infusions or beverages.
- Green tea and green tea extracts contain caffeine, which can cause insomnia, anxiety, irritability, upset stomach, nausea, diarrhea, or frequent urination in some people.
- Green tea extract contains small amounts of vitamin K, which can inhibit the effectiveness of anticoagulant drugs.
There is no reliable scientific evidence to support hoodia’s use for any condition. No clinical studies have been published to date.
The Evidence Base
- There is no evidence base on efficacy of hoodia for weight loss. No clinical studies have been published.
- There is no reliable scientific evidence to support hoodia’s use.
- Hoodia’s safety profile is unknown. Its potential risks, side effects, and interactions with medicines and other supplements have not been studied.
Mind and Body Approaches
There is considerable interest and growing scientific evidence that meditation and yoga may be useful complementary interventions in supporting behavior change and healthier lifestyles, including weight-loss and weight management programs.
To date there are only a few studies on the effects of mindfulness as a component of weight-loss programs, but the evidence is intriguing and research is ongoing.
The Evidence Base
To date, the evidence base on efficacy of mindfulness meditation for weight loss consists of few systematic reviews and a meta-analysis, in which mindfulness is a component of weight loss programs. Methodological weaknesses and variability across randomized controlled trials included in these reviews limit the strength of evidence.
- A 2014 systematic review of 19 studies (13 randomized controlled trials and 6 observational studies) found that although significant weight loss was documented among participants in mindfulness interventions for 13 of the studies, the studies do not provide evidence that clarifies the degree to which changes in mindfulness have any effect on weight loss.
- Results of another 2014 systematic review, which examined mindfulness meditation as an intervention for binge eating, emotional eating, and weight loss, suggest that mindfulness effectively decreases binge eating and emotional eating in populations engaging in this behavior; however, evidence for any benefit on weight is mixed.
- A 2013 systematic review and meta-analysis of the effect of food intake memory and awareness on eating indicates that attentive eating is likely to influence food intake, and incorporating attentive- or mindful-eating principles into other interventions may aid in weight loss and maintenance.
- Meditation is considered to be safe for healthy people.
- There is a theoretical concern, and there have been rare reports that meditation could cause or worsen symptoms in people who have certain psychiatric problems, but this question has not been fully researched.
Overall, therapeutic yoga programs can be frequently effective in promoting weight loss and are a potentially successful intervention for weight maintenance and prevention of obesity.
The Evidence Base
The evidence base on efficacy of yoga for weight loss consists of several randomized controlled trials and reviews, but the research is limited and varies in quality.
- A 2013 narrative review of yoga intervention clinical trials including weight-related outcomes concluded that overall, therapeutic yoga programs can be frequently effective in promoting weight loss and are a potentially successful intervention for weight maintenance and prevention of obesity.
- A 2011 pilot study of a 3-month yoga program for adults at high risk for developing type 2 diabetes suggests that yoga would be a possible risk reduction option for this population, and that yoga holds promise as an approach to reducing cardiometabolic risk factors and increasing self-efficacy for this group.
- Overall, those who practice yoga have a low rate of side effects, and the risk of serious injury from yoga is quite low. However, certain types of stroke as well as pain from nerve damage are among the rare possible side effects of practicing yoga.
- Yoga is generally low-impact and safe for healthy people when practiced appropriately under the guidance of a well-trained instructor.
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