Excessive perspiration is called Hyperhidrosis, and it can be a primary condition in and of itself, or it can be a secondary condition that arises as a symptom of something else. In many milder cases, primary hyperhidrosis would not be treated, but if the condition is interfering with your work or your day-to-day life there are things that can be tried.
Primary hyperhidrosis that has been a mild problem can become more severe over time for various reasons. Weight gain is one such reason, but mild primary hyperhidrosis could also become more severe if a condition that causes secondary hyperhidrosis also occurs.
The thing to understand is that this is a medical problem, not a social one. It is important that you consult with your personal physician to go over your personal and family history, and to get some tests done and referrals to any specialists he or she deems appropriate.
In my case, weight loss helped a lot, but a drug that I’m taking for other reasons may also be helping to control my perspiration.