Implementation conditions for diet and physical activity interventions and policies: an umbrella review Horodyska, Karolina, Luszczynska, Aleksandra, Hayes, Catherine B., O'Shea, Miriam P., Langøien, Lars Jørun, Roos, Gun, van den Berg, Matthijs, Hendriksen, Marieke, De Bourdeaudhuij, Ilse, Brug, Johannes (2015)