Meeting Abstract
Frequent among nutritional websites and on-line discussions are the existence of ‘negative calorie foods’; foods (e.g., celery, iceberg lettuce, and watermelon) that require more energy to digest and assimilate compared to the calories it provides. Despite these reports, there have been no scientific studies to support or refute these claims. To determine the validity that there are foods that generate a negative balance of energy, we fed celery to omnivorous bearded dragons (Pogona vitticeps) and quantified net energy balance. Following the consumption of meals equaling 5% of lizard body mass, we measured rates of oxygen consumption to quantify specific dynamic action (SDA). Lizards responded with a 75% increase in metabolic rate and a SDA equivalent to 55% of meal energy (determined by bomb calorimetry). From the collection and bomb calorimetry of feces and urate, lizards lost 20% and 14.5% of meal energy, respectively, to feces and urate. After accounting for the loss to SDA and the apparent loss to feces and urate, lizards retain 10.5% of the energy from the celery meals to be allocated to metabolism and growth. Although the net energy gained from eating celery is relatively modest, these findings challenge the widespread claims that celery is a negative calorie food.
