Not wanting to get fat, Matt nodded his head furiously.
Tim administered the antidote to him, opening his mouth and emptying the whole bottle. Matt gulped down the mysterious liquid as fast as he could, despite the bitter taste. Finally, Tim removed the empty bottle and placed it aside. Matt sighed in relief as the pressure was removed from his waist.
"Much better," He remarked, rubbing his still swollen but no longer growing belly.
"Uh, Matt..." Tim muttered, scratching the back of his head, "There are some side effects of the antidote you may want to know about." Matt raised an eyebrow.
"Like what?" He inquired suspiciously. Tim shrugged lightly.
"Well," He replied "As I said, the original solution concentrated weight gain in the stomach area. All the antidote does is redistribute weight gain all over the body." Matt's eyes widened.
"You mean-" He started to say, before he was interrupted by a weird sensation flowing through his body. Fat deposits began to grow across the length of Matt, excluding his bloated belly. His thighs began to thicken with fat. Slowly and steadily, they expanded outwards, growing wider and heavier. Matt's fatty thighs cushioned out against the bed as the blubber grew and grew. Soon, his jeans became immensely tight as his fattened thighs pressed against them. His swollen legs began to rub together. His large thighs bulged ahead of Matt's torso. Pressure built up against the seams of his jeans and his underpants.
At the same time, Matt's ass began to expand. He already had a soft rear which curved out slightly from the back of his jeans. Now, a steady stream of fat was being pumped into it, causing his buttocks to balloon out. More and more fat built up until Matt's ass hang over the back of his fat thighs. Combined with the expansion of his thighs, Matt's fattening buttocks placed even more pressure on his jeans and underpants, as the former became taut and the latter rode up the curves of his large ass.
All over his body, a similar process occurred. Matt's arms became thick and heavy. His cheeks rounded out and his face became more cherubic. Fatty deposits spread out along his frame. Even his already substantial gut surged out a little further, forcing Matt to wrench off his belt as his sagging gut pushed downwards. Finally, the growing stopped, and Matt lay back on the bed, his fat body expanding inwards and outwards as he breathed heavily.