There’s no better time then now to think about strategies to reduce a bulging waistline. Besides staying loyal to your exercise routine, a variety of diet supplements can help you achieve your weight loss goals. Here’s the latest research on the most common ingredients.
Green tea extract enhances weight loss
Green tea extract is a central ingredient in many diet formulas. It’s rich in bioactive polyphenols like EGCG (a natural catechin in green tea), which have been shown to increase thermogenesis and fat burning. The increase in energy expenditure is between 80 and 180 kcal per day, which could easily translate into improved weight loss over several months. In one study, men had two-fold greater weight loss and four-fold greater reductions in fat stores in the abdomen compared to placebo after 12 weeks of green tea supplementation (690 mg of catechins per day).
In a study just published, Italian researchers reported that EGCG supplementation resulted in better adherence to a dietary weight loss program as evidenced by fewer subjects (6%) dropping out of the program after 2 months compared to placebo (27%). In addition, feelings of fullness and satiety increased significantly while feelings of hunger decreased significantly in the EGCG group compared to the placebo group. The EGCG group also had a decrease in depressive symptoms, severity of binge eating and a decrease in insulin resistance.
These findings indicate that in addition to metabolic benefits, an EGCG-phospholipid supplement decreases the desire for food and food intake, thus improving compliance with a diet. Studies indicate that single doses up to 1,600 mg of EGCG are well tolerated and result in rapid circulating levels of EGCG. Higher doses of EGCG may not be necessary to elicit significant biological effects. One study showed a significant increase in 24-hour energy expenditure with a dose of 90 mg of EGCG, which was no different than the increase with 400 mg. In other studies, the effective doses ranged from 90 to 300 mg per day.
Bitter orange (Citrus aurantium) promotes fat breakdown
Citrus aurantium contains a potent phenolic compound called synephrine. Chemically, synephrine is similar to natural thermogenic hormones that stimulate the breakdown of fat in the body. Some research shows it specifically acts on beta-3 adrenergic receptors, which promote the use of fat, but has minimal or no stimulation of beta-1 and beta-2 adrenergic receptors, which are linked with cardiac effects. Thus, synephrine is expected to be associated with less stimulation of heart rate and blood pressure while still promoting fat breakdown and thermogenesis.
An extensive review of Citrus aurantium concluded that the evidence was promising as a weight loss agent. In one study, synephrine, in combination with ingredients like caffeine, resulted in greater weight loss and body fat loss and increased metabolic rate after 6 weeks compared to placebo. There were no reported side effects or adverse responses in markers of renal, liver and cardiovascular function.
In a published paper, healthy subjects ingested a supplement containing 21 mg of synephrine and 304 mg of caffeine before exercising. This combination supplement did not alter body temperature, fluid loss, oxygen consumption, heart rate or systolic blood pressure response to exercise, but diastolic blood pressure was slightly elevated by about 12% compared to placebo. A surprising finding was that subjects rated the exercise session easier when they ingested the combination supplement. The study provides evidence for the general safety of synephrine and caffeine and further shows they reduce the perception of effort during exercise.
Caffeine improves body weight
Similar to green tea extract, there is a solid base of research supporting positive metabolic effects of caffeine with green tea. Caffeine inhibits the enzyme phosphodiesterase, which breaks down cAMP in cells and therefore works together with EGCG to maintain the stimulatory effects of norepinephrine. Caffeine alone also increases thermogenesis and fat oxidation in a dosedependent manner. One recent study showed that moderate caffeine intake was associated with improved long-term body weight regulation and health.
Combination formulas increase metabolic rate
In many cases, diet ingredients are mixed in various combinations. Researchers tested a specialized coffee that contained added caffeine (450 mg) in combination with Garcinia cambogia (1,200 mg), Citrus aurantium extract (360 mg) and chromium polynicotinate (225 mcg). Metabolic rate and fat oxidation were assessed after ingestion of this thermogenic formula on one occasion and then during a separate trial, subjects drank a typical caffeinated coffee. Results showed that in 7 out of 10 subjects, there was a 12% increase in metabolic rate and an increase in the amount of fat burned for up to 3 hours after ingestion.
In another study, researchers tested a thermogenic supplement containing green tea extract, caffeine and an assortment of other nutrients or a non-caffeinated placebo and measured metabolic effects for 3 hours after ingestion. The most significant finding was that the thermogenic supplement raised metabolism by 106 kcal over the 3-hour period compared to placebo. This was associated with a greater increase in fatty acids in the blood, providing an indication of enhanced fat loss.
Water & protein increase thermogenesis
Another simple thing you can do to lose weight is drink more water. According to the results of two recent studies, drinking water increases thermogenesis. In one study, energy expenditure increased 23 kcal above resting over a 90-minute period after drinking about 2 cups of water. In a separate study, when 2 cups of water was consumed 30 minutes before breakfast, total calories consumed were 13% less. These studies show that simply consuming 500 milliliters of water has a dual effect of increasing thermogenesis and decreasing appetite and food consumption.
Finally, using a good protein shake or meal replacement powder is an excellent way to provide structure to your diet and stimulate metabolism. Protein is the most thermogenic nutrient, increasing metabolism by about 25% compared to modest effects of carbohydrate (8-10%) and fat (3-5%).
1. Nagao T, Hase T, Tokimitsu I. A green tea extract high in catechins reduces body fat and cardiovascular risks in humans. Obesity (Silver Spring). 2007 Jun;15(6):1473-83.
2. Rondanelli M, Opizzi A, Solerte SB, Trotti R, Klersy C, Cazzola R. Administration of a dietary supplement ( N-oleyl-phosphatidylethanolamine and epigallocatechin-3-gallate formula) enhances compliance with diet in healthy overweight subjects: a randomized controlled trial. Br J Nutr. 2008 Jul 1:1-8. [Epub ahead of print]
3. Chow HH, Cai Y, Hakim IA, Crowell JA, Shahi F, Brooks CA, Dorr RT, Hara Y, Alberts DS. Pharmacokinetics and safety of green tea polyphenols after multiple-dose administration of epigallocatechin gallate and polyphenon E in healthy individuals. Clin Cancer Res. 2003 Aug 15;9(9):3312-9.
4. Ullmann U, Haller J, Decourt JP, Girault N, Girault J, Richard-Caudron AS, Pineau B, Weber P. A single ascending dose study of epigallocatechin gallate in healthy volunteers. J Int Med Res. 2003 Mar-Apr;31(2):88-101.
5. Bérubé-Parent S, Pelletier C, Doré J, Tremblay A. Effects of encapsulated green tea and Guarana extracts containing a mixture of epigallocatechin-3-gallate and caffeine on 24 h energy expenditure and fat oxidation in men. Br J Nutr. 2005 Sep;94(3):432-6.
6. Haaz S, Fontaine KR, Cutter G, Limdi N, Perumean-Chaney S, Allison DB. Citrus aurantium and synephrine alkaloids in the treatment of overweight and obesity: an update. Obes Rev. 2006 Feb;7(1):79-88. Review.
7. Colker CM, Kalman DS, Torina GC, Perlis T, Street C. Effects of Citrus aurantium extract, caffeine, and St. John’s Wort on body fat loss, lipid levels, and mood states in overweight healthy adults. Current Therapeutic Res 1999; 60: 145–153.
8. Bui LT, Nguyen DT, Ambrose PJ. Blood pressure and heart rate effects following a single dose of bitter orange. Ann Pharmacother. 2006 Jan;40(1):53-7. Epub 2005 Nov 29.
9. Haller CA, Duan M, Jacob P 3rd, Benowitz N. Human pharmacology of a performance-enhancing dietary supplement under resting and exercise conditions. Br J Clin Pharmacol. 2008 Jun;65(6):833-40. Epub 2008 Mar 13.
10. Dulloo AG, Geissler CA, Horton T, Collins A, Miller DS. Normal caffeine consumption: influence on thermogenesis and daily energy expenditure in lean and postobese human volunteers. Am J Clin Nutr. 1989 Jan;49(1):44-50.
11. Acheson KJ, Zahorska-Markiewicz B, Pittet P, Anantharaman K, Jéquier E. Caffeine and coffee: their influence on metabolic rate and substrate utilization in normal weight and obese individuals. Am J Clin Nutr. 1980 May;33(5):989-97.
12. Acheson KJ, Gremaud G, Meirim I, Montigon F, Krebs Y, Fay LB, Gay LJ, Schneiter P, Schindler C, Tappy L. Metabolic effects of caffeine in humans: lipid oxidation or futile cycling? Am J Clin Nutr. 2004 Jan;79(1):40-6.
13. Astrup A, Toubro S, Cannon S, Hein P, Breum L, Madsen J. Caffeine: a double-blind, placebo-controlled study of its thermogenic, metabolic, and cardiovascular effects in healthy volunteers. Am J Clin Nutr. 1990 May;51(5):759-67.
14. Racotta IS, Leblanc J, Richard D. The effect of caffeine on food intake in rats: involvement of corticotropin-releasing factor and the sympatho-adrenal system. Pharmacol Biochem Behav. 1994 Aug;48(4):887-92.
15. Lopez-Garcia E, van Dam RM, Rajpathak S, Willett WC, Manson JE, Hu FB. Changes in caffeine intake and long-term weight change in men and women. Am J Clin Nutr. 2006 Mar;83(3):674-80.
16. Hoffman JR, Kang J, Ratamess NA, Jennings PF, Mangine G, Faigenbaum AD. Thermogenic effect from nutritionally enriched coffee consumption. J Int Soc Sports Nutr. 2006 Jun 5;3:35-41.
17. Dalbo VJ, Roberts MD, Stout JR, Kerksick CM. Acute effects of ingesting a commercial thermogenic drink on changes in energy expenditure and markers of lipolysis. J Int Soc Sports Nutr. 2008 Feb 20;5:6.
18. Boschmann M, Steiniger J, Franke G, Birkenfeld AL, Luft FC, Jordan J. J Am Diet Assoc. 2008 Jul;108(7):1236-9. Water drinking induces thermogenesis through osmosensitive mechanisms. J Clin Endocrinol Metab. 2007 Aug;92(8):3334-7. Epub 2007 May 22.
19. Davy BM, Dennis EA, Dengo AL, Wilson KL, Davy KP. Water consumption reduces energy intake at a breakfast meal in obese older adults. J Am Diet Assoc. 2008 Jul;108(7):1236-9.