Hi. I remember working on a project with a large pharma company around gamification for diabetics, and the core issue sounds similar.

The real question is what can I do with the points? In Crush they were mainly used for more lives to keep that addiction going. Sometimes for bonuses to get through a level. Are you doing the same purchase for the points, or is it mainly a leader board scale. Yours could be used to create and upgrade an avatar / virtual pet, which can be used to increase the self image of your players.

If those points are then also given later by a much more strenuous activity, i.e. x pounds, it may throw the game balance off. Multipliers could be used for the weight loss, to rebalance that grinding. Think about the behavioral feedback loop you want to reinforce with the player, and add the gratification at those peak moments of the cue, routine and reward.

Feel free to call if you would like to discuss the problem in more depth.