Metabolic responses to the acute ingestion of two commercially available carbonated beverages: A pilot study

After giving informed consent, twenty healthy men and women were randomly assigned to ingest 12 ounces of Celsius？ and, on a separate day, 12 ounces of Diet Coke？. All subjects completed both trials using a randomized, counterbalanced design. Metabolic rate (via indirect calorimetry) and substrate oxidation (via respiratory exchange ratio) were measured at baseline (pre-ingestion) and at the end of each hour for 3 hours post-ingestion.Two-way ANOVA revealed a significant interaction (p < 0.001) between trials in metabolic rate. Scheffe post-hoc testing indicated that metabolic rate increased by 13.8% (+ 0.6 L/min, p < 0.001) 1 hr post, 14.4% (+0.63 L/min, p < 0.001) 2 hr post, and 8.5% (+0.37 L/min, p < 0.004) 3 hr post Celsius？ ingestion. In contrast, small (~4–6%) but statistically insignificant increases in metabolic rate were noted following Diet Coke？ ingestion. No differences in respiratory exchange ratio were noted between trials.These preliminary findings indicate Celsius？ has thermogenic properties when ingested acutely. The effects of repeated, chronic ingestion of Celsius？ on body composition are unknown at this time.Over the past few decades, rates of obesity in the United States and many industrialized countries have risen at alarming rates [1]. This is disconcerting given the vast measures that have been taken to counter this effect. For example, the government's Food Guide Pyramid has been overhauled [2]; companies have introduced and/or reformulated their food products to promote lower carbohydrate or lower fat alternatives; schools have begun to ban junk foods from their vending machines; and several professional organizations have published guidelines regarding physical activity levels to promote weight loss [3-6]. Despite these efforts, Americans continue to gain weight [1].Some experts have linked the increase in obesity to the consumption of sugar-containing soft drinks [7,8]. While it is well-known caffeine has a dose-dependent effect on metabo