This study have been designed in order to compare the prognostic biomarkers and indicators related to cachexia in two groups of Gastric adenocarcinoma patients which consume a “very low carbohydrate high fat MCT oil supplemented diet” and a “standard diet”. Study design: randomized, single-center, controlled trial without blinding. Methods: after signing the informed consent 20 patients with gastric adenocarcinoma in 0-4 ECOG score which have not been gastrectomized, will be allocated randomly into control and intervention groups (intervention=10 N, control=10 N). Exclusion criteria are consist of: Diabetes, recipients of insulin or any anabolic drugs, less than 90% adherence of diets, and incidence of hypoglycemia during the intervention. Patients in intervention group are recipients of an Isocaloric low carbohydrate high fat MCT oil supplemented diet. The control group will be given an Isocaloric standard diet without changing the normal dietary components. In both groups the intervention lasts up to 6 weeks. Information will be collected at the beginning and end of the study. These variables are: weight, body mass index, resting energy expenditure, and body composition measurements. In order to evaluate the patients' performance status changes the Karnofsky scale and ECOG scoring observational methods will be used. Twenty cc of blood samples will be collected in two steps (in the beginning day and 42 days later) to evaluate ca 19-9, CEA, high sensitivity C-reactive protein, ketone bodies, fasting blood glucose, serum insulin, complete blood count and differential, serum lactate, and serum albumin.