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Over the years, a great many weight loss products have come and gone. Each new weight loss season, a fresh crop of dragon slayers is announced and by the end of the year, most of these have slipped into well-deserved oblivion. Turnover on this level tends to obscure the fact there are some approaches that work and that the fundamentals of weight control are reasonably well established, even if products are not.

In his book, Good Calories, Bad Calories: Challenging the Conventional Wisdom on Diet, Weight Control and Disease, Gary Taubes responds concisely regarding the fundamental question of what regulates fat accumulation, which is to say, weight gain. Taubes answers simply, “This was elucidated by 1965 and has never been controversial. Insulin is the principle regulator of fat metabolism...”

Insulin and Weight Management
Insulin insensitivity and poor blood sugar control are at the root of excessive weight gain. Insulin regulates hunger (the perceived need to eat) and satiety (the degree and rate at which food relieves hunger), the ability to oxidize fat for energy, and the thermic effect of food, which in lean individuals expends approximately 10 percent of all calories consumed. Insulin insensitivity leads to volatile energy levels, excessive hunger, binge eating, a reduced rate of brain response to food ingestion and a reduced thermic effect of food. In the latter case, the insulation provided by excess tissue around the trunk also is important because a reduced ability to dissipate the heat from the thermic effect of food causes the body to inhibit thermogenesis in order to regulate core body temperature. From these points, it should be clear that unless the insulin response issue and the associated hindrance of fat metabolism are resolved, there cannot be lasting weight loss. Not surprisingly, despite the common finding of statistically significant greater 24-hour energy expenditure associated with the ingestion of green tea, capsicum extracts and other thermogenic supplements, there is almost never clinically significant weight loss with any of these items. They do not address the fundamental issue.

People who are overweight are hungry more often and desire to eat more often than those who are not overweight.1 Inasmuch as insulin sensitivity controls hunger/satiety, the ability to metabolize fat for energy and fat storage, improving insulin sensitivity by itself leads to slow, but steady weight loss. This is especially apparent when carbohydrates are restricted. After several decades of refusals in medical circles even to test the low carbohydrate diet hypothesis, the tide may be turning. Researchers conducting a recent trial concluded: “Reducing glycemic load may be especially important to achieve weight loss among individuals with high insulin secretion...”2 Other researchers were more direct after a short-term trial of diabetics on a very low carbohydrate diet: “When we took away the carbohydrates, the patients spontaneously reduced their daily energy consumption by 1,000 calories a day. Although they could have, they did not compensate by eating more proteins and fats and they weren’t bored with the food choices.”3

Tackling Insulin Resistance
It should be admitted immediately that although improving insulin sensitivity is necessary for achieving lasting weight loss, doing so does not lead to the immediate loss of lots of weight. Really fast weight loss requires caloric restriction in some form, but unless handled very carefully, this leads to a greater proportionate loss of lean tissue than fat and to weight rebound. Most dieters want to lose two to three pounds per week, something that many weight loss supplements promise to deliver, yet how many such products deliver in real life and how many of those who lose more than a pound per week for eight weeks keep that weight off for a year? Very few, and almost none for two years or longer.

There are several approaches for tackling weight issues due to overeating linked to insulin resistance. One is to accept that the brains of those who are overweight simply take longer to register satiation (“fullness”) during meals. Barbara Rolls’ “volumetrics” approach of having a low-calorie soup before meals to slow food consumption so the brain can catch up is a great idea and has been proven in practice. The success, such as it is, of most “satiety” supplements is dependent on some form of volumetrics, including pre-meal meals (such as munching celery and carrot sticks prior to meals, drinking one or more glasses of water), etc.

If a dieter can live with losing approximately three to perhaps four pounds per month for a year and keeping the weight off thereafter, then insulin sensitizers and mimetics can help quite a bit. The proof of this concept is that the diabetes drugs that reduce the rate of glucose entering the system, such as metformin (lowers liver release of glucose leading to improved insulin sensitivity) and Exenatide (slows the rate of gastric emptying leading to lower blood glucose leading to a lower demand for insulin) lead to moderate weight loss in the overweight, including in childhood obesity.4,5 In one study, approximately 80 percent of women who took metformin while following a modified carbohydrate diet lost about 10 percent of their body weight within a year and just over 90 percent of them had kept the weight off four years later.6,7 These results constitute a remarkable success and they come from improving glucose control and lowering insulin levels.

Key Supplements
Unfortunately, it is quite difficult to find any dietary supplement that gives these types of results either in reducing insulin levels or improving weight loss. There are a couple of compounds discussed below that may deliver metformin-like results, but these are the exception. For instance, chromium, which improves insulin action in those who are chromium deficient, has, at best, a checkered record in weight loss trials. Weight loss benefits, if realized at all, probably require supplementation for six months or longer and are small,8 with some studies yielding null results.9

Similarly, fiber supplements often are suggested to reduce the rate at which glucose from meals enters the blood and to improve satiety, but for weight loss these supplements typically produce marginal results. For instance, out of 11 studies of glucomannan readily available on PubMed, six showed either no weight loss at all or weight loss no better than placebo. In one study, 200 overweight and obese patients received one gram of glucomannan either two or three times per day in a 16-week double-blinded, placebo controlled trial. Both doses produced approximately 4– 5 kg weight loss in four months, which was not significantly greater than that found with placebo.10 The record is no better for psyllium or guar gum than it is for glucomannan.11 In general, even when fiber supplements lead to statistically significant weight loss, the weight loss is not clinically significant.

One interesting potential alternative for weight loss is bitter melon (Momordica charantia). Half a decade ago, the similarities between the mechanisms of action of bitter melon and metformin were recognized. These include reducing excessive hepatic glucose output and reducing serum insulin.12 In the traditional systems of India, East Asia, the Caribbean and elsewhere, bitter melon as either a fresh vegetable or freshly pressed juice is widely recognized for preventing and treating diabetes as well as preventing excessive weight gain. Animal studies have confirmed these traditional uses over and over again.13,14 A recent interesting finding is that bitter melon inhibits the differentiation of primary human adipocytes.15

However, and this is a major obstacle with bitter melon, only freshly processed whole fruit, pressed juice and/or freshly produced extracts have tended to perform well. Moreover, studies on extracts from cultivars of bitter melon, which is to say, varieties deliberately selected and cultivated for commerciallydesired characteristics (usually involving table characteristics and yield), have raised doubts as to their utility in the therapy of glucose-insulin perturbations.

These problems may have been solved through use of wild genotypes of bitter melon in conjunction with special handling. In Okinawa, which is famous for good health and longevity, wild bitter melon is a great favorite and considered a premier health food. Scientific research tends to support this. For instance, one laboratory has published that extracts of bitter melon activate peroxisome proliferator receptors (PPARs) alpha and gamma; in a wild varietal, compounds capable of activating PPAR-alpha constituted as much as 7.1 g/kg of the dried material.16 PPAR-alpha increases the metabolism of fats for energy and may improve the processing of fat in the liver. In a new study, wild bitter melon was shown to rival metformin itself in regulating blood glucose in diabetic animals and also to be superior to two commercial extracts of cultivated bitter melon in areas such as nitric oxide generation and inhibition of the angiotensin-converting enzyme (ACE).17 These facts suggest that wild bitter melon, especially if properly extracted and preserved, may perform some of the other functions of metformin, as well, such as encouraging weight loss. Currently, the only Wild Bitter Melon ingredient available is Glycostat® from Glykon Technologies Group. Glycostat undergoes proprietary processing that stabilizes the material.

The great surprise, both for insulin regulation and for weight loss, is hydroxycitrate/hydroxycitric acid (HCA), just not in any of the forms that have been sold commercially until now. A highly superior form, as demonstrated in comparative and third party studies,18,19 is a specially manufactured potassiummagnesium hydroxycitrate from Glykon Technologies Group, LLC called MetaCore70™.

As those familiar with hydroxycitric acid will know already, none of the calcium-containing hydroxycitric acid salts exhibit significant effects on insulin metabolism at physiologically relevant doses, an observation verified by the fact that no one marketing them was making claims for them for insulin or blood glucose regulation. Indeed, HCA vendors have felt it necessary to add chromium and even Gymnemna sylvestre to their ingredients in order to influence blood sugar regulation. Therefore, it came as a shot out of the blue when back in 2005 results were published showing that a potassium hydroxycitrate salt and a predominantly potassium hydroxycitrate salt stabilized with a small amount of magnesium hydroxycitrate profoundly influenced insulin metabolism even though in the same tests potassium-calcium hydroxycitrate exhibited no effect.20 One startling finding in an animal model consuming both high fat and high sugar was that the same blood glucose regulation was achieved with only 50 percent of the normal level of circulating insulin.21

In 2005 it was revealed that some major Japanese researchers had abandoned the use of calcium-containing HCA salts because of lack of efficacy.22 Likewise, European researchers comparing full potassium, partial potassium and potassiumcalcium HCA salts in an animal model found that the efficacy of the salt was in proportion to the monovalent cation, i.e., calcium interfered with the efficacy of the product. An excellent review of the topic can be found in Frank Greenway, “Garcinia,” in the Encyclopedia of Dietary Supplements, 2nd Edition, 2010.

Beyond Weight Maintenance and Beyond Supplements
Visceral or belly fat can exert a major impact on health even in those who are only mildly overweight. Visceral fat is more closely linked to insulin resistance, glucose intolerance, high triglycerides and inflammation. In women, fat accumulation in the upper region of the body is common in polycystic ovary syndrome (PCOS) and is associated with metabolic complications.24 An interesting new finding is that being overweight with insulin resistance, low high-density lipoprotein cholesterol level and visceral adiposity may adversely influence adolescent bone mass.25 Continuing human studies indicate that insulin resistance and diabetes are associated with greater risk of osteoporosis.26

Diet is essential to realize greater and more enduring benefits. For weight loss, a high protein/low carbohydrate diet (40 percent calories from protein, 20–25 percent from carbohydrate and 35–40 percent from fats) with adequate omega-3 fatty acids and also adequate gammalinolenic acid (GLA) repeatedly has been shown to be more successful than low fat/restricted calorie diets. The key to using this diet successfully is to consume plenty of vegetables (one half of the plate should always be devoted to vegetables, excluding corn and potatoes, which are starches). As long as vegetables and essential fatty acids are included, this diet pattern has been proven not only to support proper weight, but also good health. After weight loss, maintenance diets in which carbohydrates account for less than 40 percent of calories and protein is in the range of 25–30 percent of calories have proven to be successful.27,28

Look Carefully at Product Validation Many weight loss products are advertised with no more than puffery. A good recent example is the vast marketing success and weight loss fiasco of acai berry. Acai berry may offer some real benefits, but those who care to investigate can quickly discover two facts. First, in Brazil, the country of origin of the berry, the fruit is used for weight gain in anemia, not weight loss. Second, at the time that acai was introduced as a weight loss agent, there were no good animal studies available, let alone any human studies. Even today, PubMed only lists 67 papers under “acai berry,” the first of which was published in 2004 and involved the fruit as a contrast agent for magnetic resonance imaging of the GI-tract. At the beginning of 2011, there is not one paper available on PubMed that looks at acai and weight loss, not even in animals. Even today, one looks in vain for a validating human weight loss trial.28 Given this recent record of deception, there are excellent grounds for consumers questioning weight loss product claims. Clinical trials are a necessary step in validation.

Conclusion One of the primary tie-ins between excessive weight and other health issues is insulin sensitivity. Savvy readers will recognize this as an aspect of Metabolic Syndrome with its manifestations of overweight, high blood pressure, central obesity, and so forth. For those of us who have strayed into the zone of excessive weight, supplements, such as the more efficacious forms of wild bitter melon and (–)-hydroxycitrate (HCA) as described above can be very helpful.


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Dallas Clouatre, PhD

Dallas Clouatre, Ph.D. earned his A.B. from Stanford and his Ph.D. from the University of California at Berkeley. A Fellow of the American College of Nutrition, he is a prominent industry consultant in the US, Europe, and Asia, and is a sought-after speaker and spokesperson. He is the author of numerous books. Recent publications include "Tocotrienols in Vitamin E: Hype or Science?" and "Vitamin E – Natural vs. Synthetic" in Tocotrienols: Vitamin E Beyond Tocopherols (2008), "Grape Seed Extract" in the Encyclopedia Of Dietary Supplements (2005), "Kava Kava: Examining New Reports of Toxicity" in Toxicology Letters (2004) and Anti-Fat Nutrients (4th edition).