Fasting and restrictive diet to lose weight among cancer survivors: profiles, sources of nutritional information, knowledges and opinions: results from the NutriNet-Santé cohort
Résumé
Background and objectives: Cancer survivors need to get more actively involved in their disease, notably through their nutritional behavior. For instance restrictive diets may be considered, including fasting practice or restrictive diets to lose weight. For the moment, no previous study has investigated theses both types of restrictive diets among cancer survivors. Aims of this study were to describe profiles of patients having practiced fasting or restrictive diet to lose weight after cancer diagnosis and to investigate knowledges/opinions of these patients and their sources of nutritional information, among cancer survivors in a large web based cohort. Methods: In the NutriNet-Santé cohort, 10,309 cancer survivors received the “Sources of information and knowledges/opinions about nutrition” questionnaire in June 2016. Among them 2,942 completed it in October 2016. Associations were explored by multivariate logistic regression adjusted for socio-professional and lifestyle factors. Results: 4.5% of participants had already practiced fasting practices since their diagnosis. They were more likely to be women (p=0.01), youngers (p=0.03), with higher educational level (p=0.003), lower incomes (p=0.004), to use dietary supplements (p=0.03) and practice higher physical activity (p=0.01). 32.2% of patients had practiced restrictive diet to lose weight since diagnosis with higher proportion of women (p<0.0001), professionally active (p<0.05), breast cancer (p=0.0008), overweight (p<0.0001), and of patients using dietary supplements (p=0.0002). Logically, patients reporting believe to the effect of fasting on improved cancer prognosis were more likely to practice fasting (p<0.0001). Contrary, there was no relation between patient’s knowledges of the links between overweight and cancer prognosis and tendency to practice restrictive diet (p=0.4). Patients who practiced fasting after cancer diagnosis were less likely to have receive nutritional information by a healthcare professional (p=0.001) and less likely to be proposed nutritional monitoring (p=0.002). Patients who practiced diet after cancer diagnosis were less likely to have received nutritional information by a healthcare professional (p<0.0001) and less likely to be proposed nutritional monitoring (p=0.0002). Conclusions: These results show that fasting was practiced for its impact on their disease, while diet was not practiced to their cancer. Discussing this matter with a healthcare professional or following a nutritional program would have an impact on practicing a restrictive diet.