It is my firm belief that the way to improve general health is through positive incentives.
Positive incentive require spending. If you're trying to reduce costs, inflation, etc. incentives may need to come in the form of penalty-avoidance. Avoiding higher premiums, costs, and/or loss of coverage is an incentive, even if you don't view it as a positive one.
If you give everyone the option of getting something for doing nothing if they fail to pursue the incentive, you are going to have people who don't bother with incentives and just take what they can get. That can drive up costs for everyone else.
Somehow connect with that basic human nature, the inner drive to obtain something desirable if it is dangled in front of their face, if you can tap into that, and i am not saying it is necessarily easy to do that, but if you can tap into that, then that's going to be the biggest driver of change you will ever see in your lifetime!
In a free market, incentives/deterrents aren't produced by intentional design. If prices rise beyond what you can afford, that is a de facto penalty. If they fall to levels that are affordable, that is a de facto incentive to buy in.
In the absence of subsidies or other market-controlling interventions, prices simply reflect interaction between supply and demand. If suppliers can provide a good or service at low cost/risk to themselves, they can make money by selling it at a low price. If, however, demand is competitive, it can push prices up because supplier have more leeway in how much they can charge while still making money. If suppliers realize they can make more money by lowering their prices, they will do so and the market price will come down to the benefit of buyers.
You see... many people dont perceive something such as losing weight as being something that is realistic.... but you dangle a wad of money in front of their nose, and all of a sudden that's something real!
A penny saved is a penny earned. If you can only qualify for low cost health insurance by achieving a certain target weight, along with other criteria; then that is an incentive. Even in the absence of insurance, achieving health saves you money, though people may be oblivious to it.
"oh i want that, but i have to lose a bit of weight, to get it, well, ok that's possible, its possible i can do that and its possible i can get that money, i can do that!"
Being overweight is an intrinsic penalty for not losing weight. Some people may just not care if they are heavy. There is perennial discussion over how to deal with obesity, and ultimately people are free to choose how to deal with their own diet/exercise/weight/health, but socializing/insuring care shifts the burden for the negative health effects of bad choices to others, so people should be able to pay more for health care that caters to their choices, if the market is willing to provide that service.
Another problem that can arise is that healthy, fit people may require so little care that there is no incentive for health providers to cater to them. They may only want to cater to unhealthy, sick people because there's more money in that. That is part of the reason why ACA was counterproductive in achieving affordability; i.e. because it gives sick people and their health care providers more power to extract more money from a wider funding base to provide expensive care to those who fail to take preventive action to reduce their health care expenses.
Ironically, there was a focus on preventive care, which was incentivized as you like, but incentives don't require people to take preventive action, so people could still shirk responsibility and be entitled to expensive care, which some people prefer because they feel more valued when they are receiving expensive care than when they are putting in personal effort to preventing the need for care.