zat yes the weight gain is always the probability .In our case ,having cruised 27 times ,we actually loose weight .Here is the secret ,we do not eat bread ,potatoes ,sugar--ala rich deserts ,ie .There is such a great variety of good foods offered that we find many temptations in those good foods .We also go to the gym daily & swim daily .The combination of eating right & exercise always works well .The ultimate benefits are health ,energy & ultimately ,a longer & productive life .