Unexplained weight gain happens when people undergo or experience substantial accumulation of added pounds that cannot be attributed to dieting or overeating. This can actually happen both ways, unexplained weight changes can either see one losing or gaining a considerable amount of weight. For both cases, there may be certain factors involved.

Unexplained weight gain usually happens when people consumes more calories that they can use. This can be brought about by overeating but also through other means such as lack of physical activity, hormonal changes as well as mood swings. It would be easy if the weight gain can be attributed to one's diet that usually is composed of too much calories that the body can use for energy. This leads the body to convert the excess calories into fat cells and store it up in the body for later use, thus resulting in weight gain.

But there are instances that weight gain cannot be directly attributed to one's diet or overeating. Some people undergo weight changes even though they try to follow the same diet routine for the longest time to maintain their weight. Unexplained weight gain in this case can be attributed other means. Some may be caused by some underlying illness or disorder. Some can also be caused by changes that happen in the body or changes in lifestyles. Here are some of the known causes of unintentional or unexplained weight gain in people.

Aging

People going through aging may experience some gradual decrease in their metabolism. This decreases the body's capacity to burn calories more efficiently which results in an excess of calories which the body converts to fat for later use. The low metabolism brought about by aging may be a cause of weight gain for people above the age of 35. Elderly people may also experience bouts of weight loss since aging may also bring about loss of appetite.

Pregnancy and menstruation

In the part of women, unexplained weight gain may be caused by one's menstrual cycle or pregnancy. The hormonal changes that happen during a woman's menstruation may cause her to gain some weight. In a similar way, a pregnant woman may also experience adding up some weight which is natural with the development of the fetus inside the womb.

Tumors

Some tumors may also be the cause of unexplained weight gain. There are some tumors, especially those that release large amounts of serotonin and other substances may also bring about unexplained weight gain in people who may have them. Most of these weight gain causing tumors are those usually located in the bile duct, pancreas, intestinal tract, the lungs or the ovaries.

Medication

Some types of medication may also help in causing unexplained weight gain in people. Certain medications such as cannabinoids, corticosteroids, insulin, sulfonylureas, and antipsychotics may contribute to weight gain in people who are using them for treatment. People using such medication are advised to talk with their doctors first before halting their treatment because of the unexplained weight gain. Abruptly stopping some of these medications may prove to be dangerous.

Lifestyle Changes

Some lifestyle changes may also be the cause of some unexplained weight gain in people. Most notable of these changes is when one quits smoking. Quitting smoking would eventually see a person gaining a bit of weight due to the changes happening inside the body brought about by quitting a bad habit such as smoking.