The effectiveness of popular, non-prescription weight loss supplements

Effectiveness of herbal medicines for weight loss: A systematic review and meta-analysis of randomized controlled trials

AIM

To update the available evidence on the efficacy and safety of complementary medicines to assist in weight loss by conducting a systematic review and meta-analysis of herbal medicines for weight loss.

METHODS

Four electronic databases (Medline, Embase, CINAHL and Web of Science) were searched from inception until August 2018. A total of 54 randomized placebo-controlled trials of healthy overweight or obese adults were identified. Meta-analyses were conducted for herbal medicines with ≥4 studies available. Weight differences of ≥2.5 kg were considered clinically significant.

RESULTS

As a single agent, only Phaseolus vulgaris resulted in a statistically significant weight loss compared to placebo, although this was not considered clinically significant. No effect was seen for Camellia sinensis or Garcinia cambogia. Statistically, but not clinically, significant differences were observed for combination preparations containing C. sinensis, P. vulgaris or Ephedra sinica. Of the herbal medicines trialled in ≤3 randomized controlled trials, statistically and clinically significant weight loss compared to placebo was reported for Irvingia gabonensis, Cissus quadrangularis, and Sphaeranthus indicus combined with Garcinia mangostana, among others, but these findings should be interpreted cautiously because of the small number of studies, generally poor methodological quality, and poor reporting of the herbal medicine interventions. Most herbal medicines appeared safe for consumption over the short duration of the studies (commonly ≤12 weeks). Some warrant further investigation to determine effect size, dosage and long-term safety.

CONCLUSION

There is currently insufficient evidence to recommend any of the herbal medicines for weight loss included in the present review.

Potential nutraceutical and food additive properties and risks of coffee: a comprehensive overview

Coffee is a composite mixture of more than a thousand diverse phytochemicals like alkaloids, phenolic compounds, vitamins, carbohydrates, lipids, minerals and nitrogenous compounds. Coffee has multifunctional properties as a food additive and nutraceutical. As a nutraceutical, coffee has anti-inflammatory, anti-oxidant, antidyslipidemic, anti-obesity, type-2 diabetes mellitus (DM), and cardiovascular diseases (CVD), which can serve for the treatment and prevention of metabolic syndrome and associated disorders. On the other hand, as a food additive, coffee has antimicrobial activity against a wide range of microorganisms, inhibits lipid peroxidation (LPO), and can function as a prebiotic. The outcomes of different studies also revealed that coffee intake may reduce the incidence of numerous chronic diseases, like liver disease, mental health, and it also overcomes the all-cause mortality, and suicidal risks. In some studies, high intake of coffee is linked to increase CVD risk factors, like cholesterol, plasma homocysteine and blood pressure (BP). There is also a little evidence that associated the coffee consumption with increased risk of lung tumors in smokers. Among adults who consume the moderate amount of coffee, there is slight indication of health hazards with strong indicators of health benefits. Moreover, existing literature suggests that it may be cautious for pregnant women to eliminate the chances of miscarriages and impaired fetal growth. The primary purpose of this narrative review is to provide an overview of the findings of the positive impacts and risks of coffee consumption on human health. In conclusion, to date, the best available evidence from research indicates that drinking coffee up to 3-4 cups/day provides health benefits for most people.

Flotation Behavior of Complex Sulfide Ores in the Presence of Biodegradable Polymeric Depressants

In this study, chitosan polymer was tested as a potential selective green depressant of pyrite in the bulk flotation of galena (PbS) and chalcopyrite (CuFeS2) from sphalerite (ZnS) and pyrite (FeS2) using sodium isopropyl xanthate as a collector and 4-methyl-2-pentanol (MIBC) as a frother. Flotation tests were carried out in a D12-Denver flotation laboratory cell in the presence and absence of chitosan and/or sodium cyanide depressant which is commercially used as pyrite depressant in sulfide mineral flotation process. Flotation recoveries and concentrate grades (assay) were studied as a function of polymer concentration and flotation time. It was found that at 50 g/ton, chitosan depressed 5.6% more pyrite as compared to conventional depressant NaCN at its optimum dosage. Furthermore, the measured assay values of pyrite in concentrates dropped by ~1.2% when NaCN depressant was replaced with chitosan polymer. Zeta potential measurements of galena, chalcopyrite, sphalerite, and pyrite suspensions before and after chitosan’s addition revealed that the polymer has preferential adsorption on pyrite minerals as compared to other sulfide minerals specially galena. Results obtained from this work show that chitosan polymer has a promising future as a biodegradable alternative to sodium cyanide for the purpose of depressing pyrite in sulfide minerals flotation.

Weight loss history as a predictor of weight loss: results from Phase I of the weight loss maintenance trial

Past studies have suggested that weight loss history is associated with subsequent weight loss. However, questions remain whether method and amount of weight lost in previous attempts impacts current weight loss efforts. This study utilized data from the Weight Loss Maintenance Trial to examine the association between weight loss history and weight loss outcomes in a diverse sample of high-risk individuals. Multivariate regression analysis was conducted to determine which specific aspects of weight loss history predict change in weight during a 6-month weight loss intervention. Greater weight loss was predicted by fewer previous weight loss attempts with assistance (p = 0.03), absence of previous dietary/herbal weight loss supplement use (p = 0.01), and greater maximum weight loss in previous attempts (p < 0.001). Future interventions may benefit from assessment of weight loss history and tailoring of interventions based on past weight loss behaviors and outcomes.

Coffee, tea and their additives: association with BMI and waist circumference

OBJECTIVE

The purposes of this study were to perform a detailed analysis how: i) the frequency of coffee/tea consumption and ii) the use of additives in coffee/tea is associated with measures of total and abdominal obesity.

METHOD

3,823 participants of the 2003-2004 National Health and Nutrition Examination Survey were examined. Obesity was assessed by BMI and waist circumference (WC). Coffee and tea consumption and use of additives were assessed by questionnaire.

RESULTS

Coffee consumption was not related to BMI or WC in either gender. However, men who drank ≥2 cups of tea per day had lower BMI (25.9 vs. 28.0 kg/m(2)) and WC (95.2 vs. 101.32 cm) values than men who never drank drink tea (p ≤ 0.05). The associations between tea consumption and BMI or WC were no longer significant after adjustment for additive use. Coffee/tea drinkers who used artificial sweeteners had larger (p ≤ 0.05) BMIs than coffee/tea drinkers who did not use sweeteners (28.2 vs. 27.1 kg/m(2) in men, 28.4 vs. 27.1 kg/m(2) in women).

CONCLUSION

Frequency of coffee/tea consumption was not associated with measures of obesity because additive use explained the association between tea consumption and obesity in men. Artificial sweetener use within coffee/tea was associated with higher BMI.

Chitosan for overweight or obesity

BACKGROUND

Chitosan, a deacetylated chitin, is a dietary supplement reported to decrease body weight. It is widely available over the counter worldwide and although evaluated in a number of trials its efficacy remains in dispute.

OBJECTIVES

To assess the effects of chitosan as a treatment for overweight and obesity.

SEARCH STRATEGY

We searched electronic databases (MEDLINE, EMBASE, BIOSIS, CINAHL, The Cochrane Library), specialised web sites (Controlled Trials, IBIDS, SIGLE, Reuter's Health Service, Natural Alternatives International, Pharmanutrients), bibliographies of relevant journal articles, and contacted relevant authors and manufacturers.

SELECTION CRITERIA

Trials were included in the review if they were randomised controlled trials of chitosan for a minimum of four weeks duration in adults who were overweight or obese. Authors of included studies were contacted for additional information where appropriate.

DATA COLLECTION AND ANALYSIS

Details from eligible trials were extracted independently by two reviewers using a standardised data extraction form. Differences in data extraction were resolved by consensus. Continuous data were expressed as weighted mean differences and standard deviations. The pooled effect size was computed by using the inverse variance weighted method.

MAIN RESULTS

Fifteen trials including a total of 1219 participants met the inclusion criteria. No trial to date has measured the effect of chitosan on mortality or morbidity. Analyses indicated that chitosan preparations result in a significantly greater weight loss (weighted mean difference -1.7 kg; 95% confidence interval (CI) -2.1 to -1.3 kg, P < 0.00001), decrease in total cholesterol (-0.2 mmol/L [95% CI -0.3 to -0.1], P < 0.00001), and a decrease in systolic and diastolic blood pressure compared with placebo. There were no clear differences between intervention and control groups in terms of frequency of adverse events or in faecal fat excretion. However, the quality of many studies was sub-optimal and analyses restricted to studies that met allocation concealment criteria, were larger, or of longer duration showed that such trials produced substantially smaller decreases in weight and total cholesterol.

AUTHORS' CONCLUSIONS

There is some evidence that chitosan is more effective than placebo in the short-term treatment of overweight and obesity. However, many trials to date have been of poor quality and results have been variable. Results obtained from high quality trials indicate that the effect of chitosan on body weight is minimal and unlikely to be of clinical significance.

Coffee and health: a review of recent human research

Coffee is a complex mixture of chemicals that provides significant amounts of chlorogenic acid and caffeine. Unfiltered coffee is a significant source of cafestol and kahweol, which are diterpenes that have been implicated in the cholesterol-raising effects of coffee. The results of epidemiological research suggest that coffee consumption may help prevent several chronic diseases, including type 2 diabetes mellitus, Parkinson's disease and liver disease (cirrhosis and hepatocellular carcinoma). Most prospective cohort studies have not found coffee consumption to be associated with significantly increased cardiovascular disease risk. However, coffee consumption is associated with increases in several cardiovascular disease risk factors, including blood pressure and plasma homocysteine. At present, there is little evidence that coffee consumption increases the risk of cancer. For adults consuming moderate amounts of coffee (3-4 cups/d providing 300-400 mg/d of caffeine), there is little evidence of health risks and some evidence of health benefits. However, some groups, including people with hypertension, children, adolescents, and the elderly, may be more vulnerable to the adverse effects of caffeine. In addition, currently available evidence suggests that it may be prudent for pregnant women to limit coffee consumption to 3 cups/d providing no more than 300 mg/d of caffeine to exclude any increased probability of spontaneous abortion or impaired fetal growth.

Dietary supplements and weight control in a middle-age population

OBJECTIVES

Obesity is rapidly becoming a health problem of epidemic proportions, bringing with it a host of health concerns. This study investigates the association of long-term (10-year) use of 14 nutritional supplements, marketed as weight-control aids, with weight change over the past 10 years among individuals age 53 to 57 years.

METHODS

Data are from the VITamins And Lifestyle (VITAL) cohort study of western Washington. Participants (n = 15,655) completed questionnaires about 10-year supplement use, diet, health habits, height, and present and former weights. The following supplements that are sometimes marketed for weight control or loss were examined: multivitamins; vitamins B6 and B12; chromium; coenzyme Q10, dehydroepiandrosterone, essential fatty acids (EFAs), fiber, garlic (Allium sativum), ginkgo (Ginkgo biloba), ginseng (Panax spp.), melatonin, soy, and St. John's wort (Hypericum perforatum). Linear regression was used to model 10-year change in weight from age 45 to ages 53-57, stratified by sex and body mass index (BMI, kg/m2) (normal, overweight, or obese) at age 45 years. Models were controlled for race/ethnicity, education, energy intake, physical activity, weight at age 45 years, and smoking.

RESULTS

Among overweight or obese men and women, long-term use of multivitamins, vitamins B6 and B12, and chromium were significantly associated with lower levels of weight gain. For example, with chromium, weight gain in the past 10 years for obese men was 11.7 lb for no use, 6.1 lb for <150 microg/day (10-year average), and a weight loss of 3.1 lb for > or = 150 microg/day (p for trend, <0.05). Among obese women, weight gain was 14.1 lb, 7.9 lb, and 3.2 lb for the three groups respectively (p for trend, <0.01).

CONCLUSIONS

These data suggest that long-term users of certain supplements experienced less weight gain than individuals who did not use the supplements. Further study is necessary before recommendations regarding these supplements can be made.

Complementary therapies for reducing body weight: a systematic review

The prevalence of obesity is increasing at an alarming rate and a plethora of complementary therapies are on offer claiming effectiveness for reducing body weight. The aim of this systematic review is to critically assess the evidence from randomized controlled trials (RCTs) and systematic reviews of complementary therapies for reducing body weight. Literature searches were conducted on Medline, Embase, Amed, and the Cochrane Library until January 2004. Hand-searches of relevant medical journals and bibliographies of identified articles were conducted. There were no restrictions regarding the language of publication. Trial selection, quality assessment and data abstraction were performed systematically and independently by two authors. Data from RCTs and systematic reviews, which based their findings on the results of RCTs, were included. Six systematic reviews and 25 additional RCTs met our inclusion criteria and were reviewed. The evidence related to acupuncture, acupressure, dietary supplements, homeopathy and hypnotherapy. Except for hypnotherapy, Ephedra sinica and other ephedrine-containing dietary supplements the weight of the evidence is not convincing enough to suggest effectiveness. For these interventions, small effects compared with placebo were identified. In conclusion, our findings suggest that for most complementary therapies, the weight of the evidence for reducing body is not convincing. Hypnotherapy, E. sinica and other ephedrine-containing dietary supplements may lead to small reductions in body weight. However, the intake of E. sinica and ephedrine is associated with an increased risk of adverse events. Interventions suggesting positive effects in single RCTs require independent replication.

The effects of a new soluble dietary fiber on weight gain and selected blood parameters in rats

This study was designed to investigate a new dietary fiber, alpha-cyclodextrin, marketed under the trade name FBCx (Wacker Biochem, Adrian, MI), for beneficial effects on weight reduction and the improvement of certain blood parameters in rats. Male Wistar rats were divided into 4 groups and fed ad libitum for a period of 6 weeks: (1) a normal low-fat diet (LF; 4% fat wt/wt); (2) an LF diet with FBCx added; (3) a high-fat diet (HF, 40% fat wt/wt); and (4) an HF diet with FBCx. The FBCx was added at the rate of 10% (wt/wt) of the fat in the diet. Body weight and food intake were recorded 3 times per week. Plasma constituent levels and liver and fecal lipid contents, as well as body composition were determined at sacrifice. Adding FBCx to the diet significantly reduced weight gain in rats fed with an HF diet relative to rats fed with the HF control diet (P < .05). FBCx also elicited a reduction in plasma triglyceride levels of 30%, total cholesterol of 9%, and increased the fat content of the feces in the rats fed with the HF diet with FBCx. In addition, the serum leptin levels were normalized, and the calculated insulin sensitivity was improved. No adverse effects were observed in the rats consuming FBCx. It would appear that FBCx might be effective in reducing body weight gain and improving metabolic syndrome.

Chitosan for overweight or obesity

BACKGROUND

Chitosan, a deacetylated chitin, is a dietary supplement reported to decrease body weight. It is widely available over the counter worldwide and although evaluated in a number of trials its efficacy remains in dispute.

OBJECTIVES

To assess the effects of chitosan as a treatment for overweight and obesity.

SEARCH STRATEGY

We searched electronic databases (MEDLINE, EMBASE, BIOSIS, CINAHL, The Cochrane Library), specialised web sites (Controlled Trials, IBIDS, SIGLE, Reuter's Health Service, Natural Alternatives International, Pharmanutrients), bibliographies of relevant journal articles, and contacted relevant authors and manufacturers. Last searches were completed in March 2004.

SELECTION CRITERIA

Trials were included in the review if they were randomised controlled trials of chitosan a minimum of four weeks duration in adults who were overweight or obese. Authors of included studies were contacted for additional information where appropriate.

DATA COLLECTION AND ANALYSIS

Details from eligible trials were extracted independently by two reviewers using a standardised data extraction form. Differences in data extraction were resolved by consensus. Continuous data were expressed as weighted mean differences and standard deviations. The pooled effect size was computed by using the inverse variance weighted method.

MAIN RESULTS

Fourteen trials including a total of 1131 participants met the inclusion criteria. No trial to date has measured the effect of chitosan on mortality or morbidity. Analyses including all trials indicated that chitosan preparations result in a significantly greater weight loss (weighted mean difference -1.7 kg; 95% confidence interval (CI) -2.1 to -1.3 kg; P < 0.00001), decrease in total cholesterol (-0.2 mmol/L; 95% CI -0.3 to -0.1; P < 0.00001), decrease in systolic (-5.9 mmHg; 95% CI -7.3 to -4.6; P < 0.0001) and diastolic (-3.4 mmHg; 95% CI -4.4 to -2.4; P < 0.00001) blood pressure compared with placebo. There were no clear differences between intervention and control groups in terms of frequency of adverse events or in faecal fat excretion. However, the quality of many studies was sub-optimal and analyses restricted to studies that met allocation concealment criteria, were larger, or of longer duration showed that such trials produced substantially smaller decreases in weight and total cholesterol.

AUTHORS' CONCLUSIONS

There is some evidence that chitosan is more effective than placebo in the short-term treatment of overweight and obesity. However, many trials to date have been of poor quality and results have been variable. Results obtained from high quality trials indicate that the effect of chitosan on body weight is minimal and unlikely to be of clinical significance.

Dietary Supplements in Weight Reduction

We summarize evidence on the role of dietary supplements in weight reduction, with particular attention to their safety and benefits. Dietary supplements are used for two purposes in weight reduction: (a) providing nutrients that may be inadequate in calorie-restricted diets and (b) for their potential benefits in stimulating weight loss. The goal in planning weight-reduction diets is that total intake from food and supplements should meet recommended dietary allowance/adequate intake levels without greatly exceeding them for all nutrients, except energy. If nutrient amounts from food sources in the reducing diet fall short, dietary supplements containing a single nutrient/element or a multivitamin-mineral combination may be helpful. On hypocaloric diets, the addition of dietary supplements providing nutrients at a level equal to or below recommended dietary allowance/adequate intake levels or 100% daily value, as stated in a supplement's facts box on the label, may help dieters to achieve nutrient adequacy and maintain electrolyte balance while avoiding the risk of excessive nutrient intakes. Many botanical and other types of dietary supplements are purported to be useful for stimulating or enhancing weight loss. Evidence of their efficacy in stimulating weight loss is inconclusive at present. Although there are few examples of safety concerns related to products that are legal and on the market for this purpose, there is also a paucity of evidence on safety for this intended use. Ephedra and ephedrine-containing supplements, with or without caffeine, have been singled out in recent alerts from the Food and Drug Administration because of safety concerns, and use of products containing these substances cannot be recommended. Dietitians should periodically check the Food and Drug Administration Web site ( www.cfsan.fda.gov ) for updates and warnings and alert patients/clients to safety concerns. Dietetics professionals should also consult authoritative sources for new data on efficacy as it becomes available ( ods.od.nih.gov ).

Effect of chitosan on weight loss in overweight and obese individuals: a systematic review of randomized controlled trials

This article aims to determine whether chitosan, a popular, over-the-counter, weight loss supplement, is an effective treatment for overweight and obesity. It is designed as a systematic review of randomized controlled trials. The data sources include the electronic databases Medline, EMBASE, Biosis, CINAHL and Cochrane Central Register of Controlled Trials (CCTR); the specialized websites Controlled Trials, International Bibliographic Information on Dietary Supplements (IBIDS), System for Information on Grey Literature in Europe (SIGLE), Reuter's Health Service, Natural Alternatives International and Pharmanutrients; and bibliographies of relevant journal articles. Included were randomized controlled trials of chitosan with a minimum duration of 4 weeks in adults who were overweight or obese and/or had hypercholesterolaemia at baseline. Fourteen trials involving a total of 1071 participants were included in the review. Analyses involving all trials indicated that chitosan preparations result in a small but statistically significant greater reduction in body weight (weighted mean difference -1.7 kg; 95% confidence interval -2.1, -1.3 kg, P < 0.00001) compared with placebo. Analyses restricted to high-quality studies showed that reductions in weight [-0.6 (-1.2, 0.1) kg, P = 0.11] were less than in lower quality studies [-2.3 (-2.7, -1.8) kg, P < 0.00001]. Results obtained from high-quality trials indicate that the effect of chitosan on body weight is minimal and unlikely to be of clinical significance.

The effect of the dietary supplement, Chitosan, on body weight: a randomised controlled trial in 250 overweight and obese adults

CONTEXT

Chitosan, a deacetylated chitin, is a widely available dietary supplement purported to decrease body weight and serum lipids through gastrointestinal fat binding. Although evaluated in a number of trials, its efficacy remains in dispute.

OBJECTIVE

To evaluate the efficacy of chitosan for weight loss in overweight and obese adults.

DESIGN AND SETTING

A 24-week randomised, double-blind, placebo-controlled trial, conducted at the University of Auckland between November 2001 and December 2002.

PARTICIPANTS

A total of 250 participants (82% women; mean (s.d.) body mass index, 35.5 (5.1) kg/m(2); mean age, 48 (12) y)

INTERVENTIONS

Participants were randomly assigned to receive 3 g chitosan/day (n=125) or placebo (n=125). All participants received standardised dietary and lifestyle advice for weight loss. Adherence was monitored by capsule counts.

MAIN OUTCOME MEASURES

The primary outcome measure was change in body weight. Secondary outcomes included changes in body mass index, waist circumference, body fat percentage, blood pressure, serum lipids, plasma glucose, fat-soluble vitamins, faecal fat, and health-related quality of life.

RESULTS

In an intention-to-treat analysis with the last observation carried forward, the chitosan group lost more body weight than the placebo group (mean (s.e.), -0.4 (0.2) kg (0.4% loss) vs +0.2 (0.2) kg (0.2% gain), P=0.03) during the 24-week intervention, but effects were small. Similar small changes occurred in circulating total and LDL cholesterol, and glucose (P<0.01). There were no significant differences between groups for any of the other measured outcomes.

CONCLUSION

In this 24-week trial, chitosan treatment did not result in a clinically significant loss of body weight compared with placebo.

Dietary supplements for body-weight reduction: a systematic review

BACKGROUND

Compliance with conventional weight-management programs is notoriously poor, and a plethora of over-the-counter slimming aids are sold with claims of effectiveness.

OBJECTIVE

The objective of the study was to assess the evidence from rigorous clinical trials, systematic reviews, and meta-analyses on the effectiveness of dietary supplements in reducing body weight.

DESIGN

The study was a systematic review. Literature searches were conducted on Medline, Embase, Amed, Cinahl, and the Cochrane Library until March 2003. Hand searches of medical journals, the authors' own files, and bibliographies of identified articles were conducted. There were no restrictions regarding the language of publication. The screening of studies, selection, validation, data extraction, and the assessment of methodologic quality were performed independently by the 2 reviewers. To be included, trials were required to be randomized and double-blind. Systematic reviews and meta-analyses of dietary supplements were included if they were based on the results of randomized, double-blind trials.

RESULTS

Five systematic reviews and meta-analyses and 25 additional trials were included and reviewed. Data on the following dietary supplements were identified: chitosan, chromium picolinate, Ephedra sinica, Garcinia cambogia, glucomannan, guar gum, hydroxy-methylbutyrate, plantago psyllium, pyruvate, yerba maté, and yohimbe. The reviewed studies provide some encouraging data but no evidence beyond a reasonable doubt that any specific dietary supplement is effective for reducing body weight. The only exceptions are E. sinica- and ephedrine-containing supplements, which have been associated with an increased risk of adverse events.

CONCLUSIONS

The evidence for most dietary supplements as aids in reducing body weight is not convincing. None of the reviewed dietary supplements can be recommended for over-the-counter use.

The eating disorders medicine cabinet revisited: a clinician's guide to appetite suppressants and diuretics

OBJECTIVE

This article explores the frequencies of use of alternative medications, available products, and their potential toxicities.

METHOD

Survey data were gathered from 39 consecutive patients diagnosed with bulimia nervosa who were seeking treatment. A survey of area outlets (health food stores, pharmacies, grocery stores) was conducted to establish a database of available agents. Putative active ingredients were identified. MEDLINE literature searches, as well as reviews of specialized texts, were performed to identify the potential toxicities of the ingredients.

RESULTS

Diet pill use was found in 64% of patients; 18 % reported use in the past month. The survey identified 167 products. Diuretic use was found in 31% of patients; 21% reported use in the past month. Twenty-five diuretic products were identified.

DISCUSSION

Alternative medicines are frequently used in the population of patients seeking treatment for bulimia nervosa. An abundance of products are available with potentially significant toxicities.

Chromium picolinate for reducing body weight: meta-analysis of randomized trials

The aim of this meta-analysis was to assess the evidence of chromium picolinate for reducing body weight. Literature searches were conducted on Medline, Embase, The Cochrane Library, Amed and Ciscom. Nine experts and four manufacturers of commercial preparations containing chromium picolinate were asked to contribute published and unpublished studies. There were no restrictions regarding the language of publication. The screening of studies, selection, data extraction, validation and the assessment of methodological quality were performed independently by two reviewers. To be included, studies were required to state that they were randomized, double-blind and placebo-controlled, and report on body weight. Ten trials met all inclusion criteria and provided data, which were suitable for statistical pooling. For body weight a significant differential effect was found in favour of chromium picolinate (weighted mean difference: -1.1 kg; 95% confidence interval (CI): -1.8 to -0.4 kg, n=489). Sensitivity analysis suggests that this effect is largely dependent on the results of a single trial (weighted mean difference: -0.9 kg; 95% CI: -2.0 to 0.2 kg, n=335). Three of the reviewed trials reported on adverse events, indicating their absence in the treatment groups. In conclusion, our meta-analysis suggests a relatively small effect of chromium picolinate compared with placebo for reducing body weight. The clinical relevance of the effect is debatable and the lack of robustness means that the result has to be interpreted with caution.

Quick weight loss: sorting fad from fact

This article reviews popular diets for their ability to produce effective weight loss. Most of the "evidence" for fad diets is based on anecdotal findings, theories and testimonials of short term results. The most prominent elements of fad diets are those of ritual and sacrifice. These diets offer quick and painless weight loss while allowing consumption of favourite or tasty foods, but place severe restrictions on certain other foods or food categories. Fad diets often work in the short term because they are low-kilojoule diets in disguise; that is, energy intake as a result of the diet is lower than the person's requirements. Successful long term weight loss depends on the consumption over a long period of time of less energy than is expended. The ideal approach is to increase physical activity while modifying eating behaviour to achieve a nutritionally balanced intake.

The safety and efficacy of pharmaceutical and herbal caffeine and ephedrine use as a weight loss agent

Since passage of the Dietary Supplement Health and Education Act of 1994, the sale of herbal dietary supplements containing caffeine and ephedrine for weight loss has become widespread in the United States. Reports of adverse events associated with the use of these non-prescription supplements have raised concerns in the United States regulatory community. Restricting the use of these products is now being considered. Such restriction should be based upon controlled clinical trials. This review of the literature in Medline relative to the use of caffeine and ephedrine in the treatment of obesity concludes that caffeine and ephedrine are effective in causing weight loss. Caffeine and ephedrine give equivalent weight loss to Diethylpropion and superior weight loss compared to dexfenfluramine. Caffeine and ephedrine have a long history of safe, non-prescription use. The adverse events accompanying acute dosing are mild and transient. Adverse events with caffeine and ephedrine reach and remain at placebo levels after 4-12 weeks of continuous treatment, but data from randomized trials up to 6 months only are available. Obesity is chronic, requires chronic treatment, its incidence is increasing and it has few effective treatments. The benefits of caffeine and ephedrine in treating obesity appear to outweigh the small associated risks. Restriction of dietary herbal supplements containing caffeine and ephedrine, often with other ingredients, should be based on controlled clinical trials of these products.

Guar gum for body weight reduction: meta-analysis of randomized trials

PURPOSE

To determine the efficacy of the dietary fiber guar gum as a therapeutic option for reducing body weight by conducting a meta-analysis of randomized controlled trials.

METHODS

Literature searches were performed on the electronic databases Medline, Embase, Biosis, Amed, and the Cochrane Library. Manufacturers of commercial guar gum preparations and experts on the subject were contacted to provide any published or unpublished trials. For inclusion, trials had to state that they were randomized, double blinded, and placebo controlled, used guar gum monopreparations, and reported body weight as an endpoint. No language restrictions were imposed. Two reviewers independently extracted data in a standardized manner according to predefined criteria and evaluated methodological quality using the scoring system developed by Jadad. Discrepancies were settled through discussion.

RESULTS

Thirty-four trials were identified and 20 could be included. Eleven trials provided data that were suitable for statistical pooling. The meta-analysis indicated a nonsignificant difference in patients receiving guar gum compared with patients receiving placebo (weighted mean difference -0.04 kg; 95% confidence interval (CI): -2.2 to 2.1). Analysis of six trials with similar methodologic features corroborates these findings (weighted mean difference -0.3 kg; 95% CI: -4.0 to 3.5). Adverse events most frequently reported were abdominal pain, flatulence, diarrhea, and cramps. Overall, 11 patients (3%) dropped out owing to adverse events.

CONCLUSIONS

This meta-analysis suggests that guar gum is not efficacious for reducing body weight. Considering the adverse events associated with its use, the risks of taking guar gum outweigh its benefits for this indication. Therefore, guar gum cannot be recommended as a treatment for lowering body weight.