A few years ago, I was moved to a new position internally, under a new manager. Said new manager really lived the Peter Principle, being an excellent developer but lacking leadership skills and being awful at deadlines.

Eventually a shared project missed a deadline, and I was thrown under the bus for his screw up. I voiced my concern, and I started getting left out of team gatherings and social activities.

Halloween came around, and he's in the team area talking about all the exercise and diets his wife is making him do. He'd been very successful, losing somewhere around 30 lbs and was confident if he stuck to it loosely he could stay under 210. I bring in candy for the holiday season, as we occasionally have children in the office. I find he cannot resist Sour Patch Kids.

Bingo

He would eat 5-7 small packs of these things a day. I kept restocking the bowl and would make sure the SPK were front-and-center so every time he'd pass he would see them and grab 1-2. I never pushed them onto him, merely made an opportunity for him to screw up.

After Halloween, I started bringing in baked goods every few days (pumpkin bars, coffee cake, etc). Slowly but surely, I started undoing his diet and exercise. He'd gone over his 210 mark, his wife was calling him during the day and stressing him, and the cold weather finally rolled through limiting his morning runs.

February rolled around, and I'd kept at this since early October. I was moving positions, and my old supervisor (who had connected the dots) said, at my going-away lunch, how I'd sabotaged his weight loss. He'd never gotten back to his 210 mark all winter, and was already over what he'd started at before the dieting/exercise. He didn't speak to me the rest of my last day.