Losing weight can be a lifelong challenge. Researchers who study obesity consider it a chronic health condition that must be managed much like high blood pressure or high cholesterol. That means there's no easy cure.

Losing just 5% to 10% of your total weight can lower blood pressure, improve cholesterol profile, prevent diabetes, improve blood sugar control if you already have diabetes, and reduce the risk of developing osteoarthritisof the knee.1-6

A combination of improved diet and regular exercise might be the best way to lose weight and keep it off.

Although prior weight-loss drugs, such as amphetamines and fen-phen, have had a patchy safety record, sibutramine (Meridia) appears to be safe and modestly effective for weight loss. New drugs currently in development will likely offer greater benefits.

It is commonly stated that the high-fructose corn syrup added to many foods is a major cause of obesity. However, while there is little doubt that, in general, excess intake of calories promotes obesity, the specific relationship of this substance to weight gain remains questionable.210

Chromium

Chromium is a mineral the body needs in only small amounts, but it's important to human nutrition.

Although it has principally been studied for improving blood sugar control in people with diabetes, chromium has also been tried for reducing total weight and body fat percentage, with some success. Both of these potential benefits involve chromium's effects on insulin. Before we can explain how chromium may help, we need to provide some background information on how the body controls its blood sugar levels.

The body needs a constant level of glucose (sugar) in the blood. When you digest a carbohydrate meal, glucose levels rise. Protein meals have the same effect, although to a lesser extent. Your body responds by secreting insulin. Insulin causes the cells of your body to absorb glucose out of the blood, thereby reducing circulating blood sugar.

Once cells have taken in glucose, they can burn it for energy or convert it to a storage form. Liver and muscle cells can store a limited amount of glucose as glycogen. Fat cells can convert unlimited amounts of glucose into energy stored as fat.

The process also goes the opposite way. When your body has used up the food from its last meal, blood glucose levels drop. Just as the body doesn't like it when glucose levels are too high, low glucose levels also cause problems. So your body applies its control mechanisms to raise blood sugar levels. It does so by reducing its output of insulin and also by raising levels of another hormone called glucagon. The net effect is that energy storage depots are mobilized. Glycogen is converted back into glucose. In addition, fat cells release their contents into the bloodstream to supply an alternate energy source.

In summary, high insulin levels build fat, while low insulin levels break down fat.

Based on this push-pull effect, if you want to lose weight you'd probably rather keep your insulin levels low.

Dieting is the most obvious method of reducing insulin. When you don't take in enough calories to supply your body's daily needs, insulin levels fall and your body breaks down fat cells. Exercising is another method; by increasing your body's energy requirements, exercise causes insulin levels to fall and fat cells to break down.

But it's difficult to consistently use more energy than you take in. Hunger takes over, and you start wanting to eat. If there were some way to trigger fat breakdown without going hungry, it would make weight loss much easier.

There's another important connection between insulin and weight to consider. Individuals who weigh too much often develop insulin resistance. In this condition, certain cells of the body become less sensitive to insulin. The body senses this, and increases insulin production until it overcomes the resistance. It is possible that fat cells respond to these increased levels of insulin by storing even more fat.

Chromium is thought to improve the body's responsiveness to insulin. Combining this fact with the insulin-weight connections just described, some researchers have proposed that chromium may assist in decreasing weight or improving body composition (the ratio of fatty tissue to lean tissue).

Their main argument goes like this: chromium increases insulin sensitivity. This causes levels of insulin to fall.88 With reduced amounts of insulin in the blood, fat cells are less inclined to store fat, and weight loss may become easier.

In addition, there is some evidence that chromium partially blocks insulin's effects on fat cells, interfering with its fat-building effect.89This could also promote weight loss. And another small study suggests that chromium may work by influencing the brain and its role in appetite and food cravings.242

There are several flaws in these arguments, though. For example, even very small amounts of insulin in the blood effectively suppress fat breakdown.90-94Another problem is that during insulin resistance, fat cells also appear to become resistant to insulin.95-98 Insulin resistance, in other words, might be a natural method of keeping the lid on weight gain. Chromium supplements might have the undesired effect of increasing the ability of fat cells to respond to insulin, helping them store fat better!

However, theory only takes one so far. It is more important to review the results of studies in which people were given chromium supplements to reduce their weight.

What Is the Scientific Evidence That Chromium Aids Weight Loss?

About ten reasonably well designed double-blind, placebo-controlledtrials have evaluated chromium’s potential benefit for weight loss.138

In the largest study, 219 people were given either placebo, 200 mcg of chromium picolinate daily, or 400 mcg of chromium picolinate daily.7 Participants were not advised to follow any particular diet. Over a period of 72 days, individuals taking chromium experienced significantly greater weight loss than those not taking chromium, over 2-½ pounds versus about ¼ pound. Interestingly, individuals taking chromium actually gained lean body mass, so the difference in loss of fatty tissue was greater: over 4 pounds versus less than ½ pound. However, a very high dropout rate makes the results of this study somewhat unreliable.

In a smaller double-blind study by the same researcher, 130 moderately overweight individuals attempting to lose weight were given either placebo or 400 mcg of chromium daily.8 Although hints of benefit were seen, they were too slight to be statistically significant.

Several other small double-blind, placebo-controlled studies also failed to find evidence of the benefit of chromium picolinate as an aid to weight loss.9-14,99,136, 211,243 One study failed to find benefit with a combination of chromium and conjugated linoleic acid.225

When larger studies find positive results and smaller studies do not, it often indicates that the treatment under study is only weakly effective. This may be the case with chromium as a weight-loss treatment.138

For more information, including dosage and safety issues, see the full Chromium article.

Pyruvate

Pyruvate supplies the body with pyruvic acid, a natural compound that plays important roles in the manufacture and use of energy. Theoretically, taking pyruvate might increase the body's metabolism, particularly of fat.

Several small studies enrolling a total of about 150 people have found evidence that pyruvate or DHAP (a combination of pyruvate and the related substance dihydroxyacetone) can aid weight loss and/or improve body composition.21-25,115

For example, in a 6-week, double-blind, placebo-controlled trial, 51 people were given either pyruvate (6 g daily), placebo, or no treatment.115 All participated in an exercise program. In the treated group, significant decreases in fat mass (2.1 kg) and percentage body fat (2.6%) were seen, along with a significant increase in muscle mass (1.5 kg). No significant changes were seen in the placebo or nontreatment groups.

Another placebo-controlled study (blinding not stated) used a much higher dose of pyruvate, 22 g to 44 g daily depending on total calorie intake.21 In this trial, 34 slightly overweight people were put on a mildly weight-reducing diet for 4 weeks. Subsequently, half were given a liquid dietary supplement containing pyruvate. Over the course of 6 weeks, people in the pyruvate group lost a small amount of weight (about 1-½ pounds) while those in the placebo group did not lose weight. Most of the weight loss came from fat.

Another interesting placebo-controlled study evaluated the effects of DHAP when people who had previously lost weight increased their calorie intake.23 Seventeen severely overweight women were put on a restricted diet as inpatients for 3 weeks, during which time they lost approximately 17 pounds. They were then given a high-calorie diet. Approximately half of the women also received 15 g of pyruvate and 75 g of dihydroxyacetone daily. The results found that after 3 weeks of this weight-gaining diet, individuals receiving the supplements gained only about 4 pounds, as compared to about 6 pounds in the placebo group. Close evaluation showed that pyruvate specifically blocked regain of fat weight.

While all these studies are intriguing, we really need large studies (100 participants or more) to establish the benefits of pyruvate for weight loss.

For more information, including dosage and safety issues, see the full Pyruvate article.

Fiber

Dietary fiber is important to many intestinal tract functions including digestion and waste excretion. It also appears to have a mild cholesterol-lowering effect and might help reduce the risk of some kinds of cancer (although the current evidence is a bit contradictory).

Fiber might also be useful for losing weight. It's thought to work in a simple way by filling the stomach and causing a feeling of fullness, while providing little to no calories. Fiber might also interfere with absorption of fat.

There are two kinds of fiber: soluble fiber, which swells up and holds water, and insoluble fiber, which does not. Soluble fiber is found in psyllium seed (sold as a laxative), apples, and oat bran. Most other plant-based foods contain insoluble fiber.

Fiber supplements may contain a variety of soluble or insoluble fibers from grain, citrus, vegetable, and even shellfish sources.

Several double-blind, placebo-controlled studies have evaluated fiber supplements as a weight-loss aid. The results have been somewhat inconsistent, but in general it appears that some forms of fiber may slightly enhance weight loss.

In one of the largest studies, 97 mildly overweight women on a strict low-calorie diet were given either placebo or an insoluble fiber (type not stated) 3 times daily for 11 weeks.26 Women given fiber lost almost 11 pounds compared to about 7 pounds in the placebo group. Participants using the fiber reported less hunger.

Researchers weren't finished with their subjects! For an additional 16 weeks, their diet was changed to one that supplied more calories. As expected, participants regained some weight during this period. Nonetheless, by the end of the 16 weeks, individuals taking fiber were still 8 pounds lighter than at the beginning of the study, while those taking placebo were only 6 pounds lighter.

Another study evaluated whether the benefits of dietary fiber endure over 6 months of dieting. This double-blind trial of 52 overweight individuals found that use of an insoluble, dietary fiber product (made from beet, barley, and citrus) almost doubled the degree of weight loss as compared to placebo.27 Once more, participants using the fiber supplement reported less hunger.

Two other double-blind, placebo-controlled studies evaluated a similar insoluble fiber product.28,116The first enrolled 60 moderately overweight women and put them on a 1,400-calorie diet along with placebo or fiber for a period of 2 months. The other study was similar, but enrolled only 45 women and followed them for 3 months. The results of both studies again showed improved weight loss and reduced feelings of hunger in the treated groups. However, a 24-week study of 53 moderately overweight individuals found no difference in effect between placebo and 4 g of insoluble fiber daily.117Another study failed to find benefit with either of two soluble fiber supplements (methylcellulose or pectin plus beta glucan) in terms of weight, hunger, or satiety.149

Glucomannan, a source of soluble dietary fiber from the tubers of Amorphophallus konjac,has also been tried for weight loss, with positive results in adults. In a double-blind, placebo-controlled trial of 20 overweight individuals, researchers found that use of glucomannan significantly improved weight loss over an 8-week period.29Benefits were also seen in a double-blind, placebo-controlled trial of 28 overweight individuals who had just experienced a heart attack.30However, another trial studied the effectiveness of glucomannan as a weight-loss agent in 60 overweight children, and found no benefit.31

An 8-week, double-blind, placebo-controlled trial of 59 overweight people evaluated the effects of chitosan, a mostly insoluble fiber from crustaceans, taken at a dose of 1.5 g prior to each of the two biggest meals of the day.32No special diets were assigned. The results showed that, on average, participants in the placebo group gained more than 3 pounds over the course of the study, while those taking chitosan lost more than 2 pounds. However, a subsequent 24-week, double-blind, placebo-controlled study of 250 people using the same dosage of chitosan failed to find benefit.150 Negative results were also seen in an 8-week, double-blind, placebo-controlled trial of 51 women given 1,200 mg twice daily 118and in a 28-day, double-blind trial of 30 overweight people using 1 g twice daily.33Although benefits have shown up in other studies, the balance of evidence indicate that chitosan probably does not work.170,205,241Further argument against the use of chitosan comes from the fact that chitosan supplements may at times contain toxic levels of arsenic.151

A few trials have only evaluated effects on hunger and satiety rather than weight loss. One study found that the soluble fiber pectin (from apples) reduces hunger sensations.34Another found that the soluble fiber guar gum slows stomach emptying and increases the sensation of fullness.35However, a more recent study evaluated the effects of guar gum in 25 women undergoing a weight-loss program, and found no influence on hunger.36In another study, consuming fiber from barley caused an increase in calorie consumption.209

Dosage

The optimum dose of fiber and the proper time to take it have not been determined.

In the first three studies described previously, insoluble fiber supplements were given 20 to 30 minutes prior to each meal at a dose of about 2.3 g, along with a large glass of water. For additional dosage information, see the full articles on Glucomannan and Chitosan.

Safety Issues

Fiber supplements must be taken with water; otherwise, they may block the digestive tract. Even when used properly, mild gastrointestinal side effects such as gas and bloating may occur.

As a kind of positive side effect, fiber supplements may reduce cholesterol and blood pressurelevels.37-41

For other important safety issues, see the full articles on chitosan and glucomannan.