by Thomas Incledon, PhD(c), RD, LD/LN, RPT, NSCA-CPT, CSCS
Introduction
It seems like more and more people are worried about fat loss these days. Unfortunately it seems like not enough of them are following a healthy lifestyle. The latest Center for Disease Control figures indicate that obesity is increasing faster than ever. We all know that exercise is part of a healthy lifestyle, but how do you keep the fat off when you can’t always make it to the gym? Luckily research has demonstrated that several different foods and supplements can help reduce body fat. Check out these brief reviews to find out which supplements are right for your individual needs.
Burning More Fat
One strategy to reduce body fat involves increasing the conversion of fat to heat. This process is called thermogenesis and while it can help reduce body fat quickly, it’s not a license to eat everything that you can get your hands on. Studies have shown that certain types of tea extracts stimulate thermogenesis [1-4]. The way this works is that a neurotransmitter called noradrenaline (NA) stimulates the production of a molecule within our cells called cyclic adenosine monophosphate (cAMP), which leads to increased thermogenesis. Certain tea extracts contain compounds called catechins along with caffeine. The catechins inhibit the enzyme that breaks down NA. The caffeine inhibits an enzyme that breaks down the cAMP. By drinking teas rich in catechins and caffeine (such as green tea) you prevent the breakdown of NA and cAMP, which means you spend more time burning fat for energy. While subtle, this effect can yield dramatic results. A green tea extract was shown to increase the number of calories burned in a day by about four percent [1]. The same extract also caused a reduction in the use of carbohydrate for energy and a ten percent increase in the use of fat for energy. These results could yield up to ten pounds of fat loss per year – without exercise!
As great as the above seems, it gets even better. Another type of tea called Oolong was actually shown to increase metabolism even more than green tea [5]. Oolong tea increased resting energy needs by ten percent compared to four percent for green tea. At first glance it might seem like drinking Oolong tea would be better than the green tea, but researchers found that the teas work for different reasons. Green tea is high in catechins and caffeine, while Oolong tea is high in polymerized polyphenols. The research suggests that by taking both teas, an even greater fat burning effect can be achieved.
Calcium for weight loss? As crazy as it sounds, it may actually be true. Research studies suggest that dietary calcium can have an anti-obesity effect [6]. Healthy sources of calcium include skim milk, fortified orange juice, sardines, beans, green leafy vegetables, and nuts. Calcium intakes of 1000 mg per day or greater are associated with lower levels of body fat [7]. Low calcium diets stimulate responses by our fat cells that result in higher levels of intracellular calcium. This leads to increased fat cell size, hypertension, diabetes, obesity, and other health problems. Higher levels of dietary calcium suppress this response so that fat cell intracellular calcium levels are lower. This serves to stimulate fat breakdown at the cellular level. Animal studies have demonstrated a reduction in body fat by 26-39% from higher calcium diets [8-10]. This is supported by human research showing that higher calcium diets are associated with lower levels of body fat, on the order of 25 pounds less body fat [8-10].
Stabilizing Blood Sugar
Insulin has become a new curse word in our every day language. Various diseases and conditions have been linked to this hormone and now everyone has jumped on the “slam insulin” bandwagon. What has escaped many people is that a number of different strategies exist that can reduce insulin levels. Many of these strategies involve stabilizing blood sugar levels so that body fat can be reduced, which leads to lower insulin levels. Both teas and coffees contain active compounds that can modify glucose levels. Black, Oolong, and green teas contain active components that inhibit the breakdown of starch in the mouth [11], exert insulin-like activity by increasing glucose use by cells, and delay glucose absorption [12]. While the various components act through different mechanisms, the end result is to lower blood glucose levels so that less glucose can be stored as body fat. Coffee contains chlorogenic acid, which slows down glucose absorption and shifts glucose absorption to distal parts of small intestine [13].
Banaba leaf is a lesser-known herb that contains a compound called corosolic acid. Animal studies have demonstrated that Banaba leaf extracts improve glucose entry into cells and can reduce body fat levels [14-17]. Similar results on glucose control have been reported for humans using an extract providing .48 mg of corosolic acid [18], which suggests that it can also reduce body fat. Another supplement that has research to support its glucose lowering actions is glucomannan. Glucomannan derived from the Konjac plant has received attention from physicians for controlling blood sugar since 1979 [19]. Several studies have shown that Konjac glucomannan can positively effect blood glucose levels [20-23] and this can lead to fat loss [24].
Blocking Fat Absorption
We all know that you need to eat less calories than you burn in order to lose weight. However science has shown that a slight modification of the “eat less than you burn” cliché can prove useful. For example, what if the fat you ingested couldn’t be broken down and absorbed? It sure would be a lot easier ( and more fun) to stay lean. A component of Oolong tea called teasaponin has actually been shown to inhibit the actions of an enzyme called pancreatic lipase that breaks down fat in the small intestine [4, 25]. By inhibiting this enzyme, the fat cannot be digested and absorbed. In this case you are not what you eat, but what you absorb.
Fat Loss Round-Up
There is an impressive amount of research steadily appearing in medical and physiological journals on the benefits of naturally occurring substances for increasing fat loss directly and/or indirectly by improving blood sugar levels. Green tea, Oolong tea, black tea, white tea, coffee (chlorogenic acid), calcium, Konjac (glucumannan), and Banaba (corosolic acid) appear to be promising compounds for the future. Taken together, these compounds may prove even more beneficial and help us keep that waist a little trimmer while we enjoy living.
References
1. Dulloo, A.G., et al., Efficacy of a green tea extract rich in catechin polyphenols and caffeine in increasing 24-h energy expenditure and fat oxidation in humans. Am J Clin Nutr, 1999. 70(6): p. 1040-5.
2. Dulloo, A.G., et al., Green tea and thermogenesis: interactions between catechin-polyphenols, caffeine and sympathetic activity. Int J Obes Relat Metab Disord, 2000. 24(2): p. 252-8.
3. Chantre, P. and D. Lairon, Recent findings of green tea extract AR25 (Exolise) and its activity for the treatment of obesity. Phytomedicine, 2002. 9(1): p. 3-8.
4. Han, L.K., et al., Anti-obesity action of oolong tea. Int J Obes Relat Metab Disord, 1999. 23(1): p. 98-105.
5. Komatsu, T., et al., Oolong tea increases energy metabolism in Japanese females. J Med Invest, 2003. 50(3-4): p. 170-5.
6. Moyad, M.A., The potential benefits of dietary and/or supplemental calcium and vitamin D. Urol Oncol, 2003. 21(5): p. 384-91.
7. Jacqmain, M., et al., Calcium intake, body composition, and lipoprotein-lipid concentrations in adults. Am J Clin Nutr, 2003. 77(6): p. 1448-52.
8. Zemel, M.B., et al., Regulation of adiposity by dietary calcium. Faseb J, 2000. 14(9): p. 1132-8.
9. Zemel, M.B., Regulation of adiposity and obesity risk by dietary calcium: mechanisms and implications. J Am Coll Nutr, 2002. 21(2): p. 146S-151S.
10. Zemel, M.B., Role of dietary calcium and dairy products in modulating adiposity. Lipids, 2003. 38(2): p. 139-46.
11. Zhang, J. and S. Kashket, Inhibition of salivary amylase by black and green teas and their effects on the intraoral hydrolysis of starch. Caries Res, 1998. 32(3): p. 233-8.
12. Hosoda, K., et al., Antihyperglycemic effect of oolong tea in type 2 diabetes. Diabetes Care, 2003. 26(6): p. 1714-8.
13. Johnston, K.L., M.N. Clifford, and L.M. Morgan, Coffee acutely modifies gastrointestinal hormone secretion and glucose tolerance in humans: glycemic effects of chlorogenic acid and caffeine. Am J Clin Nutr, 2003. 78(4): p. 728-33.
14. Hattori, K., et al., Activation of insulin receptors by lagerstroemin. J Pharmacol Sci, 2003. 93(1): p. 69-73.
15. Hayashi, T., et al., Ellagitannins from Lagerstroemia speciosa as activators of glucose transport in fat cells. Planta Med, 2002. 68(2): p. 173-5.
16. Kakuda, T., et al., Hypoglycemic effect of extracts from Lagerstroemia speciosa L. leaves in genetically diabetic KK-AY mice. Biosci Biotechnol Biochem, 1996. 60(2): p. 204-8.
17. Suzuki, Y., et al., Antiobesity activity of extracts from Lagerstroemia speciosa L. leaves on female KK-Ay mice. J Nutr Sci Vitaminol (Tokyo), 1999. 45(6): p. 791-5.
18. Judy, W.V., et al., Antidiabetic activity of a standardized extract (Glucosol) from Lagerstroemia speciosa leaves in Type II diabetics. A dose-dependence study. J Ethnopharmacol, 2003. 87(1): p. 115-7.
19. Doi, K., et al., Treatment of diabetes with glucomannan (konjac mannan). Lancet, 1979. 1(8123): p. 987-8.
20. Chen, H.L., et al., Konjac supplement alleviated hypercholesterolemia and hyperglycemia in type 2 diabetic subjects—a randomized double-blind trial. J Am Coll Nutr, 2003. 22(1): p. 36-42.
21. McCarty, M.F., Glucomannan minimizes the postprandial insulin surge: a potential adjuvant for hepatothermic therapy. Med Hypotheses, 2002. 58(6): p. 487-90.
22. Vuksan, V., et al., Konjac-mannan (glucomannan) improves glycemia and other associated risk factors for coronary heart disease in type 2 diabetes. A randomized controlled metabolic trial. Diabetes Care, 1999. 22(6): p. 913-9.
23. Vuksan, V., et al., Beneficial effects of viscous dietary fiber from Konjac-mannan in subjects with the insulin resistance syndrome: results of a controlled metabolic trial. Diabetes Care, 2000. 23(1): p. 9-14.
24. Gallaher, D.D., et al., A glucomannan and chitosan fiber supplement decreases plasma cholesterol and increases cholesterol excretion in overweight normocholesterolemic humans. J Am Coll Nutr, 2002. 21(5): p. 428-33.
25. Han, L.K., et al., Anti-obesity effects in rodents of dietary teasaponin, a lipase inhibitor. Int J Obes Relat Metab Disord, 2001. 25(10): p. 1459-64.
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