The study investigated the impact of a multi-ingredient nutritional supplement (MINS) on resting metabolic rate and energy expenditure. The supplement contained a combination of factors that are normally administered in isolation (32 g protein, 8.4 g CHO, 1.7 g fibre, 105 mg caffeine and 21 mg green tea extract with 10.5 mg catechins, per 50 g serving. 18 subjects participated in the study (10 males, 8 females), mean age 21.8 yrs. Following overnight fasting, subjects ingested either MINS or an isocaloric maltodextrin placebo. Resting oxygen uptake was determined by gas analysis measuring VCO2 produced and VO2 consumed. 7 days later, the protocol was repeated using a randomised twotreatment crossover design so each individual subject’s response to both placebo and supplement was assessed. Results showed mean resting Respiratory Exchange Ratios were 0.77 ± 0.03 after supplementation, compared with 0.93 ± 0.03 after placebo (P<0.05), indicating a shift in contribution of fat to metabolism from 24 ± 2.5% (Control) to 79 ± 1.9% (MINS). Mean resting metabolic rate was found to be 3.69 ml per kg.min-1 O2 after supplementation, compared with 3.45 ml per kg.min-1 O2 after placebo. Whilst this difference is not statistically significant, it impacts on the absolute amount of fat metabolised at rest, increasing from 0.3 kcal.min-1 (Control) to 1.0 kcal.min-1 (MINS) (P<0.05). These findings may have significant implications for individuals involved in weight loss or weight management programmes.