Westerners are too obese, and presumably part of that's to do with the enjoyment people get from unhealthy foods.
Whereas if you can't taste anything food's basically differently textured fuel of varying temperatures. You'd have to desire to eat e.g. yogurt with added sugar over one without.
So in your mind, there are alternative, inexpensive 6- and 12-packs of plain, unsugared yogurt sitting in national grocery chains, just waiting to be consumed by people with no sense of taste at scale?
Edit: also keep in mind that people who have lost 40% of their sensory input are apt to go through a depression, and that being sedentary has a lot of risk factors that overlap with the risks from obesity.
Some people might with diminished (but not completely eliminated) senses of smell might compensate by eating more of certain flavors that they CAN taste. Also worth noting that there are tons downsides, ignoring the obvious lack of sensory pleasure most people get from food. They are less likely to smell rotten and spoiled food, smell smoke from a nearby fire, etc.