Losing bodyfat is a simple proposition: You simply take in fewer calories than you burn. All successful diets, no matter what the macronutrient ratios, are based on that simple principle. In practice, however, many other factors enter the metabolic picture. Examples include hormonal status, such as whether you’re insulin insensitive or whether your thyroid hormone factor is optimal. Another is how your fat cells respond to sympathetic hormone stimulation, which promotes fat-cell release and fat oxidation. Many people who have too much bodyfat show a blunted sympathetic response, as do those over age 40.
Since a decreased daily calorie intake is the cornerstone of any fat-loss plan, you must also consider the source of your calories. Dietary fat, at just over nine per gram, is the most concentrated source of calories. Protein and carbohydrates each have four per gram. Most mainstream dietitians suggest that dietary fat is the most expendable calorie source. Saturated fat offers few nutritional benefits and is linked to the onset of cardiovascular disease.
As far as real-world experience is concerned, many people get fat from eating not just too much fat but also too much carb. You can eat a significant amount of fat and not get fat if you exercise and keep your carb intake low. That’s the basis of popular diets such as the Atkins low-carb plan. But if you add high-fat intake to a high-carb intake, as most obese people do, the result is increased bodyfat.
Carbohydrates are the body’s preferred fuel, even though it has no actual nutritional requirement for carbs (they can be made in the liver from amino acids, glycerol, lactate and other sources), and when you eat fat with carbs, the fat is stored, not oxidized. Even worse, a high saturated-fat intake leads to insulin insensitivity, which further compounds the bodyfat-increasing effect.
Last month I discussed how hydroxycitrate is thought to act as a type of carbohydrate blocker, in the sense that it inhibits an enzyme that converts carbs into fat. The problem with hydroxycitrate is that it has no direct effect on fat. Another supplement, however, is reputed to be a potent fat blocker: chitosan.
What Is Chitosan?
Chitosan is a type of dietary fiber derived from chitin, which, in turn, is derived from the shells of shellfish. Chitin is a protein-sugar complex that the shellfish industry at one time considered merely a waste product, but when chitosan was discovered to have remarkable capacity for absorbing grease and fat, it found a niche in industrial applications as a means of soaking up grease. That property didn’t escape notice of the natural-foods industry, which began marketing chitosan as a fat blocker.
Chitosan can attract fat particles because it’s a positively charged compound and fat is negatively charged. The electrochemical difference makes fat adhere to it. Some studies show that chitosan can absorb four to six times its weight in fat, as well as cholesterol, which is not technically a fat. For every gram of chitosan you eat, you should prevent the absorption of four to six grams of fat. The obvious caveat here is that you must take in chitosan before you eat the fat for it to work, either at the same time as a fatty meal or right before.
Because of its ability to bind to bile acids’which would lower cholesterol’chitosan functions like soluble fiber. On the other hand, the body treats it as an insoluble fiber, since it isn’t digested and most of it winds up being excreted. In theory, chitosan should pull some fat out of the body with it.
The original studies with chitosan involved rats and investigated its cholesterol-lowering ability. They all indicated that chitosan does lower cholesterol, at least in rodents. The doses used, however, were far greater than any human would likely take. The question is, Does it work as well in a normal human body?
Chitosan and Fat Loss
When similar studies focused on humans, the cholesterol decline was far more modest, though many subjects showed a drop in potentially dangerous low-density lipoprotein (LDL) cholesterol.
Several studies involving human subjects have also evaluated chitosan for fat-loss purposes. The initial studies showed that chitosan appeared to be an effective adjunct to a decreased-calorie diet. The obvious problem here is whether the fat loss resulted from chitosan or the diet itself. Another study set out to answer that question by having subjects take chitosan as part of their normal diets.1 If chitosan blocked fat absorption, it should show some effect on any type of eating program, or so reasoned the authors. The study featured a randomized, double-blind protocol, meaning that neither the subjects nor the people administering the study initially knew who was taking chitosan or a placebo. For 28 days 34 overweight people took four 250-milligram capsules of either chitosan or a placebo twice daily.
At the end of four weeks neither group showed changes in body mass index or any effect on cholesterol, triglycerides or fat-soluble vitamins; however, vitamin K, a fat-soluble vitamin, did significantly increase in the chitosan group. As for side effects, six people in the chitosan group and two in the placebo group complained of constipation, which is curious, since chitosan acts as a fiber in the body.
That particular study is often cited as proof of the inefficacy of chitosan for fat-loss purposes. But there were several confounding factors. For example, the authors don’t say when the subjects took the chitosan. Unless they took it with the meal itself, or just before, the supplement would do absolutely nothing. The study also didn’t discuss the fat content of the average meal the subjects ate. Unless the meals were high in fat, chitosan wouldn’t offer any benefits. ALL Although the subjects’ total chitosan intake (two grams a day) was in the suggested range, it pales in comparison to the 15-to-22-times-higher dosages used in animal studies that did show fat blocking. That revelation smacks of the early anabolic steroid studies ‘proving’ that steroids were ineffective for building muscle. Years later researchers realized that the doses used in the studies were too small to help build huge muscle mass, a fact that athletes had known for years.
Finally, the capsules of chitosan the study used were mislabeled. The supplement distributor had stated that they contained 71 percent chitosan, but they actually contained 42 percent. That may not have made a major difference in the results, but it points up the notion that the dose was inadequate to have any significant effect on fat loss.
Another hint about dosage inadequacy was chitosan’s null effect on cholesterol. Other studies with human subjects have shown reductions in cholesterol ranging from 5.8 to 42.6 percent, with LDL drops averaging 15.1 to 35.1 percent.2,3
A double-blind, placebo-controlled randomized study presented at the 11th European Congress of Obesity noted the discrepancies in existing research on chitosan and sought to determine its effectiveness. The subjects were 50 obese women, randomly assigned to either a chitosan group or a placebo group. Those in the chitosan group took two chitosan capsules three times daily before each meal, with each capsule containing 750 milligrams of chitosan. Both groups ate the same diet, containing only 1,000 calories a day.
After six months those in the chitosan group lost 12.3 kilograms of bodyfat compared to 7.4 kilograms in the placebo group. The women in the chitosan group also showed a significant decline in blood pressure, which may be related to the overall weight loss, although the drop in blood pressure in the placebo group was considerably lower. Neither group showed any changes in fat-free mass. The authors note that the results obtainable from chitosan may depend on such factors as product solubility, molecular weight and viscosity, which implies that cheap chitosan may not work.
Chitosan’s fat-blocking effect came into question with the publication of another study involving seven obese men who were put on a high-fat diet (120 grams of fat daily) for 12 days.4 On days six to nine they took a total of 15 chitosan capsules, or 5.25 grams, prior to meals. They also took a charcoal marker to determine fat excretion. The results showed no increase in fat excretion.
The authors noted that in animal studies showing chitosan to be effective for fat-blocking purposes, the chitosan was actually mixed into the animal feed so it would interact with the fat content before the meal was consumed. In the human study, although the subjects got the chitosan prior to high-fat meals, it may not have mixed with the fat sufficiently or long enough to cause a significant effect.
A more recent study appears to have confirmed the ineffectiveness of chitosan capsules for fat blocking.5 In this study 15 men ate five meals a day for 12 weeks, with no energy restrictions, meaning they ate whatever they wanted. During a four-day control period they took no supplements. During another four-day period they took two capsules five times a day, containing a total of 4.5 grams of chitosan, 30 minutes before meals.
The subjects got an average 132 grams of fat daily. According to the claims made by advertisers, they should have excreted 44 grams of fat. In actuality, however, they excreted only 1.1 grams. Based on that, the actual fat-binding capacity of chitosan was calculated to be 0.25 grams of fat per gram of ingested chitosan. Thus, to get a 50 percent reduction in fat digestibility, the men would have needed to take 264 grams of chitosan, or 587 capsules, a day. Put another way, with the 10 capsules a day they were getting in the study, it would take 778 days to lose one kilogram (2.2 pounds) of fat.
A drug currently being promoted for weight loss, orlistat (Xenical), does inhibit fat absorption by inhibiting lipase, a fat-digesting enzyme. The suggested dose is calculated to prevent digestion of 30 percent of any fat in a meal.
A study comparing orlistat to chitosan assigned seven men and five women randomly to either an orlistat group getting 120 milligrams or a chitosan group getting 890 milligrams, which participants took three times daily for one week.6 They all ate a 2,500-calorie diet containing 30 percent fat for the entire 21-day study. After a week the groups switched supplements. While orlistat significantly worked as advertised, chitosan had no effect.
Some evidence shows that combining chitosan with vitamin C makes it work better. On the other hand, chitosan could block the absorption of such fat-soluble vitamins as A, D, E and K, as well as carotenoids like beta-carotene and lycopene. Chitosan may also adversely affect the uptake of flavonoids and zinc. People with allergies to shellfish of any kind need to completely avoid chitosan supplements. Add it all up, and you’ve got to conclude that chitosan’s weight-loss effects are mild at best, as are its effects on decreasing elevated blood lipids, such as cholesterol. The main problem with chitosan isn’t so much its effectiveness as the way it’s been overhyped. Advertisements imply that simply taking it prior to a high-fat meal will ‘neutralize’ the fat, thereby enabling you to eat what you want with impunity.
The sad truth is that no such dieting panacea exists. Perhaps one day it will be developed, but in the meantime the only known way to get rid of fat is by burning it through the blood, sweat and sometimes tears of hard, regular training and dieting.
1 Pittler, M., et al. (1999). Randomized, double-blind trial of chitosan for body weight reduction. Eur J Clin Nutr. 53:379-81.
2 Ylitalo, R., et al. (2002). Cholesterol-lowering properties and safety of chitosan. Arzneimittelforschung. 52:1-7.
3 Bokura, H., et al. (2003). Chitosan decreases total cholesterol in women: randomized, double-blind, placebo-controlled trial. Eur J Clin Nutr. 57:721-5.
4 Gades, M.D., et al. (2002). Chitosan supplementation does not affect fat absorption in healthy males fed a high-fat diet, a pilot study. Int J Obesity. 26:119-22.
5 Gades, M.D., et al. (2003). Chitosan supplementation and fecal fat excretion in men. Obesity Res. 11:683-88.
6 Guerciolini, R., et al. (2001). Comparative evaluation of fecal fat excretion induced by orlistat and chitosan. Obes Res. 9:364-67. IM