It's so they can have another excuse for their pile. They go to the gym maybe 2-3 times and waddle on the treadmill for 5 minutes. Then they spend half an hour taking very obviously posed selfies in full makeup and "workout" clothes. After finally realizing that just being in a gym doesn't carve 100s of lbs off their fatasses like a christmas ham, they stop going and toss it in the "I did all I could, but nothing changed" pile.   Losing weight is primarily done by eating less.  Eating is all they exist for so actually eating less and eating "better" would most likely give them a mental breakdown.