May 16, 2013
Managing appetite, hunger and caloric intake is one noble approach to weight management, but equally important is burning calories. Metabolism within the body's cells creates heat and energy. This heat production, called thermogenesis, is a component of metabolism. Resting metabolic rate (RMR), the energy the body expends to perform necessary survival functions, can decrease with age and alongside declining lean body massincreased fat tissue causes RMR to slow, while increased muscle mass, which burns more energy, causes RMR to rise. Increasing thermogenesis in brown adipose tissue (BAT) via the diet and supplementation has been studied by natural products researchers for possible approaches to weight management.
The adrenal glands naturally produce the compound 3-acetyl-7-oxo-dehydroepiandrosterone, known as 7-oxo-DHEA or 7-keto. This substance affects several enzymes glycerol-3-phosphate dehydrogenase, malic enzyme and fatty acyl CoA oxidasecentral to thermogenesis. As a supplement, 7-oxo-DHEA (as 7-Keto®, from Humanetics) has been linked to substantial weight and body fat reduction, as well as increased RMR in adults on a calorie-restricted diet, compared to placebo.1,2,3
Citrus aurantium, known as bitter orange, increases thermogenesis by acting on certain beta-adrenoreceptors (beta-3), without stimulating the receptors (alpha-1 and -2, and beta-1 and -2) that affect heart rate and blood pressure, making C. aurantium different from stimulants such as ephedra. While confirming C. aurantium (as Advantra Z®, from Nutratech Inc.) supplementation in conjunction with a strict diet and exercise resulted in body fat reduction, Georgetown University Medical Center researchers concluded the supplement may be the best thermogenic substitute for ephedra, which was banned by FDA for safety reasons.4
Other research demonstrated Advantra Z as a meal replacement improved the thermogenic effect of food without affecting heart rate and blood pressureepinephrine excretion increased 2.4-fold.5 A thorough review of C. aurantium safety conducted by a multi-academic panel of experts and published in 2011 concluded evidence (89 clinical studies and other references) showed bitter orange and its active constituent synephrine-p are "exceedingly safe," with no attributable serious adverse effects.6
Studies on green tea have proven it delivers weight management benefits independent of its caffeine content, instead owing to thermogenesis. Caffeine impacts the uncoupling proteins involved in BAT thermogenesis, but Swiss researchers suggested an interaction between the tea catechin epigallocatechin gallate (EGCG) and caffeine may be the root of green tea's fat-burning activities.7
In healthy men, green tea extract (50 mg caffeine and 90 mg EGCG) significantly increased fat oxidation/metabolism and energy expenditure, compared to men taking just caffeine.8 In other research, EGCG alone increased fat oxidation in the first two days of supplementation.9 Further, a non-caffeinated green tea extract (as GreenSelect® Pyhtosome, from Indena) taken by obese adults on a calorie-restricted diet significantly reduced weight and BMI compared to the diet-only group.10 Lipid and insulin-related parameters also improved in the treatment group as did leptin levels.
In addition to its direct weight-loss effects, green tea's EGCG may improve compliance with dietary regimens. A University of Central Florida, Orlando, study investigating a blend of 100 mg EGCG and 170 mg N-oleyl-phosphatidylethanolamine (NOPE)as PhosphoLean, from Chemi Nutra) in conjunction with a low-calorie diet, moderate exercise found improved dietary compliance in the healthy overweight adult subjects (men and women) at four weeks, but not at eight weeks.11 While the supplement did not affect body mass or body fat, hunger and binge eating compared to placebo, there was improvement to mood score, feeling of fatigue and confusion, which speaks to the emotional factors in dieting stress.
Fucoxanthin, a carotenoid from brown algae, performs a similar action on white adipose tissue (WAT), where it promotes expression of uncoupling proteins, ramping up fat metabolism and energy production.12 The addition of medium-chain triacylglycerols (MCTs) or fish oil to fucoxanthin supplementation may amplify the UCP-1 expression and fat burn, according to animal research.13.14
A combination of fucoxanthin-rich brown seaweed extract and pomegranate oil (as Xanthigen, from P.L. Thomas) taken for 16 weeks by non-diabetic, obese premenopausal women with nonalcoholic fatty liver disease (NFALD) promoted weight loss, decreased body and liver fat content and improved liver function, in conjunction with increased resting energy expenditure.15
References are listed on the next page.
1. Zenk JL et al. HUM5007, a novel combination of thermogenic compounds and 3-acetyl-7-oxo-dehydroepiandrosterone: Each increase the resting metabolic rate of overweight adults." J Nutr Biochem. 2007;18:629-34.
2. Zenk JL et al. The effect of 7-Keto Naturalean on weight loss: A randomized, double-blind, placebo-controlled trial." Curr Ther Res. 2002;63:263-72.
3. Kalman DS et al. A randomized, double-blind, placebo controlled study of 3-acetyl-7-oxo-dehydroepiandrosterone in healthy overweight adults." Curr Ther Res. 2000;61:435-442.
4. Preuss HG et al. Citrus aurantium as a thermogenic, weight-reduction replacement for ephedra: an overview." J Med. 2002;33(1-4):247-64.
5. Gougeon R et al. Increase in the thermic effect of food in women by adrenergic amines extracted from citrus aurantium." Obes Res. 2005 Jul;13(7):1187-94.
6. Stohs SJ et al. The Safety of Citrus aurantium (Bitter Orange) and its Primary Protoalkaloid p-Synephrine." Phytother Res. 2011 Apr 8. doi: 10.1002/ptr.3490.
7. Dulloo AG et al. Green tea and thermogenesis: interactions between catechin-polyphenols, caffeine and sympathetic activity." Int J Obes Relat Metab Disord. 2000 Feb;24(2):252-8
8. Dulloo AG 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 Dec;70(6):1040-5.
9. Boschmann M and Thielecke F. The effects of epigallocatechin-3-gallate on thermogenesis and fat oxidation in obese men: a pilot study." J Am Coll Nutr. 2007 Aug;26(4):389S-395S.
10. Diepierro F et al. "Greenselect Phytosome as an adjunct to a low-calorie diet for treatment of obesity: a clinical trial." Altern Med Rev. 2009 Jun;14(2):154-60.
11. Mangine GT et al. "The effect of a dietary supplement (N-oleyl-phosphatidyl-ethanolamine and epigallocatechin gallate) on dietary compliance and body fat loss in adults who are overweight: A double-blind, randomized control trial." Lip health Dis.2012;11:127.
12. Maeda H et al. Seaweed carotenoid, fucoxanthin, as a multi-functional nutrient." Asia Pac J Clin Nutr. 2008;17 Suppl 1:196-9.
13. Maeda H et al. Effect of medium-chain triacylglycerols on anti-obesity effect of fucoxanthin." J Oleo Sci. 2007;56(12):615-21.
14. Maeda H et al. Dietary combination of fucoxanthin and fish oil attenuates the weight gain of white adipose tissue and decreases blood glucose in obese/diabetic KK-Ay mice." J Agric Food Chem. 2007 Sep 19;55(19):7701-6.
15. Abidov M et al. The effects of Xanthigen in the weight management of obese premenopausal women with non-alcoholic fatty liver disease and normal liver fat." Diabetes Obes Metab. 2010 Jan;12(1):72-81.
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