BACKGROUND This study explored the frequency of cardiac cachexia in Mexican patients, the role of anthropometric variables as predictors of its development and its association with food intake and physical activity. METHODS Seventy three patients with systolic heart failure were included in the study. Cardiac cachexia was defined as weight loss of >6.0% in 6 months. Anthropometric data, physical activity and dietary intake were evaluated by a 3-day questionnaire at the beginning of the study and 6 months later. RESULTS After 6 months of follow up, 14 (19%) patients developed cachexia with a mean weight loss of 12.1+/-3.4%. Significant decrease in the anthropometric variables were observed in patients which developed cachexia except in the waist to hip ratio, which increased in these patients due to bigger diminish of hip circumference than in the waist one. The subjects which developed cachexia had significant less physical activity after 6 months (-6.9%) in comparison with the non cachexic group. Reported energy intake did no differ among groups. Patients with cardiac cachexia showed greater prevalence of obesity and overweight, a high body fat percentage and a low arm circumference. CONCLUSIONS Cardiac cachexia development was not related with low energy intake or increase in the total energy expenditure (explained by the physical activity). The only variable related to cachexia development was lower physical activity.