Food in the lab is a special kind of diet translated into natural science terms and parameters but also I find ‘food as nutrients' show itself as so much more than nourishment when prescribed or eaten as such. In this paper I interrogate the facts and measuring practices of nutritional scientists in the context of the 'ad libitum meal'. The analytical interest is thus what kind of eaters and bodies are enacted in the meal test and what ideas of prevention and treatment are embedded in their standards. Drawing from ongoing empirical work among Danish obesity researchers performing scientific meal tests I ask what make up food stuff and eaters in the meal tests? More specifically I explore a scientific testing of changes in taste preferences before and after weight-loss surgery using an ad libitum buffet with a selection of different foods and another testing the effect of exercise on appetite also using an ad libitum meal consisting of spaghetti bolognaise. I analyse the entanglement and concurrence of different knowledge practices and show how several scalings of appetite play out, one ex explaining the aim of the test, being to ”measure what your body would want the most” and hence producing an eater who: ”shouldn't restrain herself”. Practices of food and eating in the test meal I suggest, will allow us to tackle reductionism by showing the complex cultural context shaping clinical intervention.