A few years ago, more or less with the prodding of my mother and paleo sister, I made some life style changes.
I stopped eating most forms of sugarcane. And I stopped using aluminum based* deodorant.
These are hard things to do. Assuming that you're stopping from a normal American lifestyle, chances are your system is used to being chock full of sugar, and ditto for aluminum under your arms.
There's a detox period. It's horrible. If you're giving up aluminum, something in your body overcompensates for the sudden lack of the metal. The result is a terrible personal stench. It goes away after a few weeks as the microbe ecosystem that is your sweat glands recalibrates itself. But the in the meantime, you're standing 10 feet away from everyone and avoiding all stressful situations. I used to try to time this with spring break or winter holiday when I was in college. It took more than one try to drop it completely.
For sugar, it's also a few week adjustment period of insatiable cravings and irritability.
But! Once your over both of these and your body has recalibrated to be sugar cane / aluminum free, strange cool science shit happens. You can smell when you eat sugar!! My BO changes, not in a good or bad way, it just smells a bit sweeter the day after having a slice of cake. Same goes with veganism and meat. My diet makes me smell different. I find this amazingly cool.
The smell changes, to me, are a bigger indication of the impact diet has on your body composition. What I eat matters for more than how I feel, or how much the scale says I weigh**. It also matters for the dude sitting next to me on the bus.
What a sweet feedback loop!
*Aluminum is an antiperspirant. You can buy deodorant that doesn't contain aluminum.
**Weighing yourself is a sloppy proxy measuring health.