Why do people get fat in a short period of time?

The first thing most people associate with gaining weight is what a person eats and drinks. However, that is NOT always the case!

"Water weight" - Fluid Retention

The phrase "short period of time" should serve as a clue to the cause of weight gain. Weight gain put on rapidly over one day, several days, or within a month is most often fluid retention or "water weight". A small amount of fluid retention, held for a short period of time, can occur in healthy individuals. For examples: slight edema (swelling) around the ankles after standing for 8 hours; or fluid retention associated with a woman's menstrual cycle. When a worker or menstruating woman props their feet up or lies down, the fluid is more easily shuttled to the kidneys to be processed as waste.

However, in kidney and liver disease, a person can put on fluid weight extremely fast. Ascites, fluid in the abdomen, can make an otherwise slim person (man or woman) look 8 months pregnant. The faster that weight increases, kidneys and/or liver should be investigated as a cause. Also diseases of the heart can dramatically cause fluid retention overnight. For example, Congestive Heart Failure, which can be life threatening.

Cell and Tissue "Fat"

Both high blood glucose (hyperglycemia / Diabetes) and certain types of low blood glucose (hypOglycemia) can add fat cells, mostly to the abdomen (belly fat). This normally takes months to years. But anyone who puts on weight quickly, especially despite exercise and careful nutrition, should have an A1C blood test done for Diabetes. If negative, they should have a blood test done for Reactive Hypoglycemia.

Childbearing age teens and women

Some endocrine conditions can cause fat cell weight gain despite being active and eating right. The biggest cause is Hypothyroidism. When the thyroid condition is treated, the person might be able to lose weight.

Poycystic Ovarian Syndrome (POS) can also cause continuing weight gain despite being active and eating right. Fluid filled benign cysts grow on the ovaries. These interfere with how a woman's body uses the normal hormones the body produces. When a teenager or woman of "childbearing years" (age 13 to late 40s) has a large abdominal girth, whether gained slowly or rapidly, she should be checked for ovarian cysts. A simple ultrasound can show this.

Some cysts can grow to "grapefruit size" or larger. These need watched and evaluated for possible surgery.

Medications

YES, many medications can cause increased water weight, or increased eating leading to increased fat cell weight.

Depression and Other Mental Health medications

Many medications for mental illness can cause increased water weight, or increased eating leading to increased fat cell weight. As well, depression can cause increased eating, decreased activity, and low motivation.

"Then, there's just fat" - a person is overweight

Lastly, yes, inappropriate nutrition, excess calories and fat, and lack of exercise account for most cases of being overweight to obese.

However, no layperson should ever, ever automatically conclude that a person just "eats too much" or "is just lazy" if the person is overweight or obese. Only doctors can evaluate bloodwork and physical condition to say whether a person's weight is solely due to eating and inactivity.

So never jump to conclusions when you see someone who is overweight. Don't spread biases. Instead, use your knowledge about the different causes for fluid retention and "fat cell" increases in body weight.