There are plenty of reasons why we gain weight and accumulate fat. As long as one is fine with the way they look and feel comfortable with themselves and their health, everything is perfect. But if you are worried that you are becoming unhealthy, here are some of the reasons why you may be gaining weight. A few like genetics and others can't be changed and require medical attention, but others can be controlled and you can get fit in no time! Also a common point to note, there are two types of fit: slim and regular. While two people can look so different in shape and size, they can still be fit. So don't confuse thick body type to being fat.