Fat Blockers: Do They Work?

March 25, 2011 6:28 am 5 comments

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By: Naoko Okuma and Mike Ormsbee, PhD, CSCS, CISSN
Date Published:
March 2011

Let’s be honest. When it comes to losing weight, more and more people look for the fastest and easiest way to shed those extra pounds. Currently, Americans spend more than 30 billion dollars on weight loss products and services each year(3). The traditional option of daily exercise and a balanced nutrition plan (read: it works, but not many people like to do it!) seems to be old news as the interest is geared towards other alternatives. The supplement industry is well aware of this desire to lose fat fast and there are a myriad of proposed solutions available that lure many people into investing in these products. However, the question remains…do any of these fat loss supplements actually work and what exactly are they doing to our bodies? Let’s find out.

The Fat Behind Fat

Simply put, fats carry many calories. At 9 kcals per gram, the amount of calories in 1 gram fat is higher than 1 gram of protein or carbohydrates. One pound of fat is roughly equal to 3500kcal! When we eat fat, whether it is the fat in a piece of pizza or a scoop of ice cream, your body must break down ingested fat so that it can be absorbed and used. Pancreatic lipase is the primary enzyme that breaks down these large fat droplets in the small intestine(2). Without this enzyme, fat will remain too fat for the body to absorb and will just end up being excreted.

Therefore, this is where the potential solution in weight loss and fat loss may lie!  What if there is a way to stop the ability for fat to be broken down, by inhibiting the action of pancreatic lipase, so fat is excreted rather than absorbed? The assumption that follows is if fat is not absorbed, then fat will not be stored in the body (read: hello six-pack).  With this background (albeit limited), let us see what fat loss products actually work.

Fat Loss Supplements


Chitosan derived supplements claim to absorb or trap fat and prevent fat from being absorbed in the body(4). Chitosan is a product found in the shells of crustaceans like shrimp and crabs and is thought to mix with fat in the stomach and then trap fat droplets in the small intestine, preventing it from being broken down by pancreatic lipase(12). The good news is that research shows that chitosan does in fact inhibit the activity of pancreatic lipase (the enzyme necessary for the breakdown of the large fat molecules into smaller products), preventing fat from being absorbed. Unfortunately, there is a catch.  The bad news is that the data linking chitosan to decreased fat absorption are based on animal studies that looked at rats that were given very large doses of chitosan – a dose of chitosan that would not be administered to humans(5,6). When chitosan was studied in humans, the effects seen in rats were not observed. In fact, short-term studies report no significant changes in body weight or fat binding capabilities when ingesting chitosan(8, 9). Other studies have observed the fat binding effects of chitosan in men, but no effects in women(7). However, the benefit was so minimal that it would take more than 7 months for a person to lose 1 lb of fat (7)!  Despite the lack of significant findings, other researchers have observed significant weight loss with only 28 days of chitosan intake in overweight or obese individuals(32), however, the weight loss may have been more due to the dietary restrictions involved, and not so much the chitosan supplementation(32). Although there may be some fat binding effect of chitosan in long-term consumption, the beneficial effects appear to be minimal, making the drastic weight loss claims for these chitosan-based supplements misleading at best.

FDA-approved Options


Many of you may have seen Alli®, a weight loss medication that can be bought at major supermarkets and drug stores. Alli® is a relatively new product released in 2007, but Alli® is simply the over-the-counter version of the stronger, prescription form, known as Xenical®(11). Interestingly, to add to the confusion, both Alli® and Xenical® are the trade names for the same pharacogical drug known as Orlistat.  What makes Alli® so special compared to other supplements is that it is the first over the counter diet drug that has been approved by the FDA(14).  Interestingly, since October 24th, 2009, the FDA has been conducting a safety review of Orlistat, because of adverse side effects associated with liver problems(13).

Does Orlistat work?

Nevertheless, research in non-human studies indicates that Orlistat does inhibit the action of the pancreatic lipase (16, 17). However, the same caveat applies that we saw earlier – does Orlistat work when used in humans? It appears so! Short-term Orlistat intake results in fat maldigestion in humans as well (18).  When 12 healthy men and women (18 to 45 years old) took Orlistat for 7 days, the result was a significant increase in the amount of fat excreted in the feces (Read: interesting but not pleasant)(9). But what about weight loss? A one-year study looked at the effects of Orlistat and weight loss in obese individuals, and it was observed that with a combination of a low calorie diet, more individuals who took Orlistat lost weight (an average of 5% more weight lost) than the individuals who just stuck to the low calorie diet. It is important to note that “more individuals” in this research is referring to 35% of the individuals who took Orlistat, whereas there were 21% of the individuals who did not take Orlistat who had significant weight loss (17).  It is also important to be aware that most of the research conducted looking into Orlistat and weight loss have been based on overweight and or obese individuals, and the weight loss effects of Orlistat in normal weight individuals is something that is still unknown.

Side Effects

But wait! Although there seems to be enough data out there for weight loss associated with Orlistat, the problem may lie in potential adverse side effects. Although these side effects associated with Orlistat may only be mild to moderate gastrointestinal issues, they may become an inconvenience in the everyday lifestyle. Would you want oily stools, abdominal pain, nausea, diarrhea, flatulence and even hemorrhoids (9,11,17,20)? Moreover, with the recent FDA watch on Orlistat with potentially serious liver problems, the safety on Orlistat will have to wait until these issues are further investigated.

Another major side effect of taking Orlistat could be the shrinking of your wallet! Alli® is fairly expensive, ranging from around $50 to $70 per month, which will definitely add up over time. Additionally, much of the scientific research that has observed effective weight loss with Orlistat usually used the dosage of the prescription amount in Xenical (120mg of Orlistat); there is only half of this amount in Alli (60 mg of Orlistat)! One study found that weight loss associated with Orlistat was dose dependent, meaning that obese subjects lost more weight with a larger dose of Orlistat of 360 mg, than taking in smaller doses of 30 mg and 180 mg (19). Note that this 360mg of Orlistat is a huge dose even compared to the prescription Xenical. Although the weight loss has been scientifically documented, whether weight loss can be achieved with the small dose of Orlistat in Alli becomes questionable.

Natural Products

Good news for those not interested in pills or supplements! The inhibition of fat absorption does not just lie in the weight loss supplements mentioned above. Surprisingly, there are many natural products being proposed that may inhibit the actions of pancreatic lipase, which may eventually lead to the development of new anti-obesity drugs (20).

The Power of Tea

The health benefits of tea, especially green tea, have become somewhat of a recent phenomenon in western cultures. Still, many people remain unaware of another type of tea, called Oolong, which has health benefits similar to other teas, but is thought to be especially touted for its anti-obesity effects (21).  Research in rats has shown that partially fermented oolong tealeaves had some of the strongest weight reduction effects of teas. Not only that but it also may help to lower triglyceride levels in the blood (22).  It appears that the oolong tea polymerized potent polyphenols (plant compounds) in oolong tea possesses a strong inhibitory action on pancreatic lipase (23). In overweight and obese humans, those who drank 4 cups of oolong tea/day (8g of tea) for 8 weeks observed slight improvements in body weight and waist size without significant changes in diet (24).  In addition, the amount of excreted fat is greater when healthy adults consume a polyphenol enriched oolong tea with high-fat diets (26). This response is similar to using Orlistat! What’s more is that oolong tea increases metabolism and has resulted in a 12% increase in the fat oxidation (burning) with an intake of full-strength oolong tea (15g of tea) (25). This increase in metabolism has also been observed in studies looking into green tea, which may reflect similar health benefits associated with both green and oolong tea. Therefore, oolong tea consumption may carry a powerful punch as it not only may inhibit fat absorption to the body, but it may also increase fat burning, without the side effects associated with some of the weight loss supplements!

The Bottom Line

Be smart when coming across any weight loss product claiming rapid weight loss. Although it may be tempting if a product claims 10 to 15 lbs of weight loss in a week, just know that this is unhealthy, and rapid weight loss does not achieve long-term results (35).

Be critical when investing in weight loss supplements as the company’s claims and the real truth behind the scientific research may be inaccurate, misleading, and just plain crazy. Remember that the FDA assumes that the consumers buying these products are well aware of these products, so make sure to do exactly that. Research, read, and investigate what these weight loss products are really about and then make a decision of whether to take it or not. Do not forget that the excellent fat loss plan of proper nutrition and a regular intense exercise regime is scientifically proven and actually does work!


Mike Ormsbee Ph.D., CSCS, CISSN earned his doctorate from East Carolina University and is a certified sports nutritionist (CISSN) and strength and conditioning specialist (CSCS).  Dr. Ormsbee’s research and expertise has focused on training and eating to prevent obesity-related diseases, achieving optimal body composition and optimizing athletic performance. He currently teaches at Florida State University.


  1. US Food and Drug Administration. Dietary Supplement Health and Education Act of 1994. Available at: http://www.fda.gov/Food/DietarySupplements/default.htm. Accessed October 12, 2009.
  2. QuackWatch. How the Dietary Supplement Health and Education Act of 1994 Weakened the FDA. Available at: http://www.quackwatch.org/02ConsumerProtection/dshea.html (Accessed Octrober 12, 2009)
  3. FTC. Weight-loss advertising. An analysis of current trends: A Federal Trade Commission Staff Report (Sept. 2002). Available at: http://www.ftc.gov/bcp/reports/weightloss.pdf (Accessed October 12, 2009)
  4. Gades MD, Stern JS. Chitosan Supplementation and Fecal Fat Excretion in Men. Obes Res 11 (5): 683-688, 2003
  5. Sumiyoshi M, Yoshiyuki K. Low molecular weight chitosan inhibits obesity induced by feeding a high-fat diet long-term in mice. J Pharm Pharmacol 58 (2): 201-207, 2006
  6. Han LK, Kimura Y, Okuda H. Reduction in fat storage during chitin-chitosan treatment in mice fed a high-fat diet. Int J Obesity 23: 174-179, 1999
  7. Gades MD, Stern J. Chitosan supplementation and fat absorption in men and women. J Am Diet Assoc 105 (1): 72-77, 2005
  8. Pittler MH, Abbot NC, Harkness EF, Ernst E. Randomized, double-blind trial of chitosan for body weight reduction. Eur J Clin Nutr 53:379-381, 1999
  9. Guerciolini R, Radu-Radulescu L, Boldrin M, Dallas J, Moore R. Comparative evaluation of fecal fat excretion induced by Orlistat and chitosan. Obes Res 9 (6): 364-367.
  10. Mhurchu CN, Poppitt SD, McGill AT, Leahy FE, Bennett DA, Lin RB, Ormrod D, Ward L, Rogers A. The effect of the dietary supplement, Chitosan, on body weight: a randomized controlled trial in 250 overweight and obese adults.
  11. O’Meara S, Riemsma R, Shirran L, Mather L, Riet G. A rapid and systematic review of the clinical effectiveness and cost-effectiveness of Orlistat in the management of obesity. Health Technol Asses 5(18): 2001
  12. Kanauchi O, Deuchi K, Imasato Y, Shizukuishi M, Kobayashi E. Mechanism for the inhibition of fat digestión by chitosan and for the synergistic effect of ascorbate. Biosci Biotech Biochem 59 (5): 786-790, 1995
  13. Us Food and Drug Administration. Early communication about an ongoing safety review Orlistat (marketed as alli and xenical). Available at: http://www.fda.gov/Drugs/DrugSafety/PostmarketDrugSafetyInformationforPatientsandProviders/DrugSafetyInformationforHeathcareProfessionals/ucm179166.htm (Accessed October 13, 2009)
  14. Forrester MB. Pattern of Orlistat exposures in children aged 5 years or less. J Emerg Med: 1-4, 2007
  15. Tiss A, Lengsfeld H, Verger R. A comparative kinetic study on human pancreatic and thermomyces lanuginose lipases: inhibitory effects of tetrahydrolipstatin the the presence of lipid substrates. J Mol Catal B-Enzym: 1-8, 2009.
  16. Lookene A, Skottova N, Olivecrona G. Interaction of lipoprotein lipase with the active-site inhibitor tetrahydrolipstatin (Orlistat). Eur J Biochem 222: 395-403, 1994
  17. Finer N, James WPT, Kopelman PG, Lean MEJ, Williams G. One-year treatment of obesity: a randomized, double-blind, placebo-controlled, multicentre study of Orlistat, a gastrointestinal lipase inhibitor. Int J Obesity 24: 306-313, 2000
  18. Ashraf H, Hildebrand P, Meier R, Beglinger, Niklaus G. Induction of artificial fat maldigestion by tetrahydrolipstatin assessed by the 13C-heiolein breath test in healthy volunteers. Digestion 62: 159-163, 2000.
  19. Drent ML, Larsson I, William-Olsson T, Quaade F, Czubayko F, von Bergmann K, Strobel W, Sjostrom L, van der Veen EA. Orlistat (RO18-0647), a lipase inhibitor, in the treatment of human obesity: a multiple does study. Int J Obesity 19(4): 221-226, 1995.
  20. Birari RB, Bhutani KK. Pancreatic lipase inhibitors from natural sources: unexplored potential. Drug Discov Today 12(19/20): 879 – 889, 2007.
  21. Toyoda-Ono Y, Yoshimura M, Nakai M, Fukui Y, Asami S, Shibata H, Kiso Y, Ikeda I. Suppression of postprandial hypertriglyceridemia in rats and mice by oolong tea polymerized polyhenols. Biosci Biotechnol Biochem 71(4): 971-976, 2007.
  22. Kuo KK, Weng MS, Chiang CT, Tsai YJ, Lin-Shiau SY, Lin JK. Comparative studies on the hypolipidemic and growth suppressive effects of oolong, black, pu-erh, and green tea leaves in rats. J Agric Food Chem 53; 480-489, 2005.
  23. Nakai M, Fukui Y, Asami S, Toyoda-Ono Y, Iwashita T, Shibata H, Mitsunaga T, Hashimoto F, Kiso Y. Inhibitory effects of oolong tea polyphenols on pancreatic lipas in vitro. J Agric Food Chem 53: 4593-4598, 2005.
  24. He R, Chen L, Lin B, Matsui Y, Yao X, Kurihara H. Benefitical effects of oolong tea consumption on diet-induced overweight and obese subjects. Chin J Integr Med 2009 15(1): 34-41, 2009.
  25. Rumpler W, Seale J, Clevidence B, Judd J, Wiley E, Yamamoto S, Komatsu T, Sawaki T, Ishikura Y, Hosoda K. Oolong tea increases metabolic rate and fat oxidation in men. J Nutr 131 (11): 2848-2852, 2001
  26. Hsu TF, Kusumoto A, Abe K, Hosoda K, Kiso Y, Wang MF, Yamamoto S. Polyphenol-enriched oolong tea increases fecal lipid excretion. Eur J Clin Nutr 60: 1330 – 1336, 2006
  27. Bendsen NT, Hother AL, Jensen SK, Lorenzen JK, Astrup A. Effect of dairy calcium on fecal fat excretion: a randomized crossover trial. Int J Obesity 32 (12): 1816-1824, 2008
  28. Jacobsen R, Lorenzen JK, Toubro S, Kro-Mikkelsen I, Astrup A. Effect of short-term high dietary calcium intake on 24-h energy expenditure, fat oxidation, and fecal fat excretion. Int J Obesity 29 (3): 292-301, 2005
  29. Boon N, Hul GBJ, Stegen JHCH, Sluijsmans WEM, Valle C, Langin D, Viguerie N, Saris WHM. An intervention study of the effects of calcium intake on faecal fat excretion, energy metabolism and adipose tissue mRNA expression of lipid-metabolism related proteins. Int J Obesity 31 (11): 1704-1712, 2007
  30. Shahkhalili Y, Murset C, Meririm I, Duruz E, Fuinchard S, Cavadini C, Acheson K. Calcium supplementation of chocolate: effect on cocoa butter digestibility and blood lipids in humans. Am J Clin Nutr 73(2): 246-252, 2001
  31. Welberg JWM, Monkelbann JF, de Vries EFE, Muskiet FAJ, Cats A, Oremus E, Boersma-van Ek W, van Rijsbergen H, van der Meer F, Mulder NH, Kleibeuker JH. Effects of supplemental dietary calcium on quantitative and qualitative fecal fat excretion in man.
  32. Ernst E, Pittler MH. Chitosan as a treatment for body weight reduction? A meta-analysis. Perfusion 11(11): 461-465, 1998
  33. National Institute of Diabetes and Digestive and Kidney Diseases. Choosing a Safe and Successful Weight-loss Program. Available at http://win.niddk.nih.gov/publications/choosing.htm. Accessed November 3, 2009
  34. Laquatra, I. Nutrition for weight management. In: LK Mahan, S Escott-Stump (eds),  Krause’s food, nutrition, &diet therapy, Philipelphia (PA) : Saunders; 2004, 558-593
  35. National Institute of Health. The practical guide: identification, evaluation, and treatment of overweight and obesity in adults. October 2000. Available at http://www.nhlbi.nih.gov/guidelines/obesity/prctgd_c.pdf. Accessed November 3, 2009


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