Nathan began to never let Charles skip a meal. Even his lukewarm complaints and excuses of having 'something important to do' became quieter and less common. Nathan stayed present if at all possible as well, fixating on the plates disappearing before his eyes. He liked to eat as well and would accompany Charles with his own huge servings. And this was just for his meals proper. Snacks went from few and far between to constantly stashed in Charles' desk and in his pockets. Nathan made sure of this.
Charles grew accustom to these daily stuffing sessions. His already full stomach would be so swollen he'd enter barely functional status by lunch if he were lucky. He had no clue how it felt to skip a meal or feel hunger of any kind past a tinge of discomfort. Nathan didn't just make sure he packed on a healthy amount of weight like he assured them both he would. He was rapidly packing a dozen or so pounds on Charles on a monthly basis throughout the year without a break. The year anniversary of Charles' returning had come to pass with a grand total of 150lbs of fat. This brought him to double his original weight. The 15lbs Charles had lost during his disappearance, which worried Nathan so, was brought back tenfold.
Pants never lasted two months on Charles' rapidly expanding waistline. He became so well aware yet unable to do anything to retaliate at his bulging form. It seemed like the fatter he got the more food became available to him, or maybe that was due to his expanding appetite that learned to know no bounds. The morning he reached 350lbs he ashamedly folded his biggest pair of trousers back into his wardrobe and opted for 3X sweatpants. The sweatpants he bought to wear for his 'exercise routine' that he swore up and down he'd start the beginning of this week.
Three servings of heavy breakfast foods and the post-meal bloating left Charles unable to consider moving from his seat. Once a slave to the strict routine of perfecting his body; the only routine he was able to adhere to was his (over) eating schedule. He was well aware that it was either hop on board with saving his physique now or forever grow into larger clothes and lose every bit of athleticism. Exercise was inevitably postponed until further notice.
Nathan made sure that exercise stayed on the back burner and didn't have a chance of interrupting Charles steady gain into irreversible obesity.