If you are an avid user of social media, particularly Instagram, I'm sure you will have come across varying fitness models/bloggers who frequently post about 'tea' products they have used to help sculpt out their body.
Now I must admit, usually when I see this I roll my eyes because my thinking is 'are they really selling this shit as the reason they have such low body fat percentages rather than the strict diet and training plan they stick to'? However, I'm not one to judge without doing my research first so I've taken a look at a very recent Review Article from the American Journal of Clinical Nutrition and I must admit, the outcome has opened my mind somewhat. If you want to check out the article here's the link: http://ajcn.nutrition.org/content/98/6/1682S.long
The study looked at three types of tea - green tea, oolong tea and white tea - all of which come from the leaves of the Camellia sinesis L species of plant. All three teas contain several polyphenolic (the components of food which have no energy giving roles but exert effects on the body in different ways).
The researchers had a primary interest in two components of the tea products, the catechins and caffeine. Catechin polyphenols have been reported to have an effect on body weight whilst caffeine, which is actually quite abundant in tea, possesses thermogenic effects and can help stimulate the breakdown of fat by stimulating our central nervous systems.
The authors list several supporting studies detailing the various effects which both caffeine and catechins may have on body weight. I won't go through them all here for risk of putting you to sleep, however I will mention the headlines.
The habitual tea consumption may have positive effects on body composition variables as shown by Wu et al. Habitual tea drinkers for 10 years showed a 19.6% reduction in body fat percentage and a 2.1% reduction in waist:hip ratio compared with non habitual tea drinkers. Another study looked at a group who had followed a 1200kcal diet/day for 4 weeks and then received a green tea treatment of 8 weeks. After the intervention, subjects not only maintained their body weight but they lost 5.8 kg and showed a decrease in fat percentage of 4.7% and preservation of lean body mass. The placebo group did not show any significant changes in anthropometric variables.
The most beneficial effects may come when combining caffeine and catechins as seen in green tea, oolong tea and white tea. These have been studied in quite some detail over the long term with weight loss and weight maintenance as the key outcomes. In the short term, the combined effects on energy expenditure and fat usage are quite promising and have beneficial effects on weight loss and weight maintenance. For example, Vieira Senger and colleagues, observed a significant weight loss of 1.2 kg in 24 elderly subjects who consumed green tea for 60 days compared with a control group of 21 age-matched subjects who did not lose weight.
Metabolic variables have also been studied as outcome markers with serum cholesterol, insulin, glucose, and triglycerides being studied in healthy and overweight/obese subjects. It was concluded, catechins in combination with caffeine may be able to improve biomarkers of the metabolic syndrome such as HDL cholesterol, LDL cholesterol, total cholesterol, insulin, and glucose.
The author also looked at catechins either in combination with caffeine or alone with respect to exercise endurance capacity and exercise tolerance. In chronic studies, catechins, in combination with moderate-intensity exercise, may change anthropometric variables to a greater extent than exercise alone. Also, in athletes, it has been shown that fat mass was reduced after a combination of catechins and exercise.
The reason for such benefits include catechins and caffeine rich tea simulating the cellular mechanism responsible for fat oxidation, an increase in energy expenditure through stimulation of brown fat pathways, a reduction of glucose metabolism allowing fat to be used instead, an increase in adrenaline (which helps to increase body fat usage) and a reduction of fat absorption when storing energy in the body.
Before recommendations can be made about dosage and definitive conclusions can be drawn from the data, further research is needed. For my best efforts, I was unable to read all of the studies referenced and the authors failed to include the inclusion and exclusion criteria to which they used for referenced studies. Therefore, the quality of the studies mentioned throughout the study could be questionable and may not be consistent with each other. As a result, conclusions may be misleading and not applicable in a real world setting. Many studies have been conducted in animals which are not always applicable to human subjects and therefore may indicate a lack of quality in study design. Furthermore, different study designs and types of catechins and caffeine products were used throughout the data and thus varying effects have been observed.
It is also vital to stress that such benefits, although promising, are not a replacement for a healthy balanced diet and cannot be used in isolation for significant weight loss effects. Instead, tea supplementation may complement a healthy diet and regular physical activity regime but it will not be the difference between success and failure. Therefore, I would still recommend caution when being promised miracle weight loss products but I do concede the research is interesting.
Hurdle, R and Westerterp-Plantenga, M., S. Catechin- and caffeine-rich teas for control of body weight in humansAm J Clin Nutr 2013;98(suppl):1682S–93S.
Hughes LA, Arts IC, Ambergen T, Brants HA, Dagnelie PC, Goldbohm RA, van den Brandt PA, Weijenberg MP. Higher dietary flavone, flavonol, and catechin intakes are associated with less of an increase in BMI over time in women: a longitudinal analysis from the Netherlands Cohort Study. Am J Clin Nutr 2008;88:1341–52.
Vieira Senger AE, Schwanke CH, Gomes I, Valle Gottlieb MG. Effect of green tea (Camellia sinensis) consumption on the components of metabolic syndrome in elderly. J Nutr Health Aging 2012;16:738–42.
Wu CH, Lu FH, Chang CS, Chang TC, Wang RH, Chang CJ. Relationship among habitual tea consumption, percent body fat, and body fat distribution. Obes Res 2003;11:1088–9)