Sudden Weight Gain Causes, Diseases and Prevention

It is not uncommon to gain a few pounds after the festive seasons as most people are less active when not working and tend to overindulge in food. However, significant weight gain is not sudden, as in overnight. If or when sudden gain occurs, like within a 24 to 48 hour period, then it could be a sign of various diseases. It may require medical investigation, especially if it is accompanied by symptoms like swelling of the legs, excessive abdominal distension or difficulty breathing.

Reasons for Higher Body Weight

Most of us associate an increased body weight with a higher than normal body fat content. The body fat percentage does rise in cases of being overweight or obese. However, it is not fat alone that may be responsible. Food, feces and fluid are other factors that can contribute to weight gain. Furthermore the other body organs and structures also contribute to body weight. Most notably is the bones and in some diseases an increased bone density increases the body weight.

Abdominal Obesity

Fat, Food, Fluid or Feces

Obesity is a global problem. Being overweight or obese means that there is an accumulation of FAT. However, body weight can also suddenly change when:

  • FOOD: Large amounts of food is consumed and still held within the gut.
  • FLUID: Large amounts of fluid is consumed and retained within the body with some diseases.
  • FECES: Large amounts of feces retained within the bowels.

Video on Weight Loss Myths and Mistakes

The following video was produced by the Health Hype team.

Causes of Sudden Weight Gain

Fat accumulation does not explain overnight weight gain. Rising body weight due to fact accumulation occurs gradually, over weeks, months and even years. Therefore it is mainly food, fluid and feces that causes as sudden and excessive weight gain over a few days. This can be due to dietary or lifestyle changes, or it can also be due to certain diseases that can affect appetite, hamper bowel movements or impair urine output.


Overeating is one of the most common causes of sudden weight gain. It is not an uncommon habit for most people from time to time. The weight gain that will occur instantly will correlate to the weight of the food that was consumed in large meal. For example, a person will weigh approximately 2 pounds more after consuming 2 pounds of food and beverages.

abdominal pain after food

The breakdown of this food to produce energy or the loss of fluid through perspiration or in exhaled air is not sufficient to suddenly counteract the weight gain associated with the food consumption. Certain diseases may lead to an abnormally increased appetite and bingeing with certain eating disorders may also be considerations in sudden weight gain due to overeating.


Constipation is another common cause of sudden weight gain. With feces collecting in the bowels, a person may find that there body weight is increasing. The quantity of stool within the bowels can vary from 1 pound to 4 pounds. Therefore people who are constipated may find sudden weight loss after a large volume bowel movement.

Constipation is often related to dietary and lifestyle factors, like insufficient fluid intake, low dietary fiber and being sedentary. However, constipation can also be a symptom of several diseases and disorders. Many cases of constipation occur for no clearly identifiable reason.

Diarrhea Bowel Movement Pain with Stool

Impacted Feces

Feces can become a hard compressed mass. In this case the feces cannot be passed out and remains ‘stuck’ in the colon and rectum. This is known as fecal impaction. It can block the passage of stool higher up in the bowels that is not impacted. However, a person may not realize that fecal impaction is present since small amounts of watery stool which can move around the impaction may be expelled.


Edema is the medical term for swelling. It occurs when fluid accumulates in any part of the body like in the limbs (peripheral edema) or even in the abdominal cavity (ascites). Fluid can also occur in the lungs (pulmonary edema) or around the lungs (pleural effusion) or around the heart (pericardial effusion). Sometimes fluid accumulation can be generalized. This means it occurs all over the body which is known as anasarca.

Obesity Cancer Risk

Fluid retention in the body can occur for several reasons:

  • Kidney diseases.
  • Liver diseases.
  • Heart failure.
  • Malnutrition.
  • Iatrogenic – side effects of certain medication or excessive IV fluid administration.

How To Prevent Sudden Weight Gain?

Always consult with a doctor about treating sudden weight gain that may be linked to disorders or diseases. However, as certain dietary and lifestyle factors may be responsible, the following remedies may be helpful in preventing sudden weight gain.

  • Do not overeat. Practice moderation with food, particularly with quantity. If there is a wide choice of food, rather have small quantities of several foods. Stop before there is a stuffed feeling. Try to space small meals every few hours rather than having a few very large meals.
  • Consume fluids in moderation if there are underlying kidney or other diseases that may cause fluid retention. Always follow a doctor’s recommendation about the consumption of water and other beverages.
  • Beware when rehydrating after an episode of dehydration. By consuming fluids without the right balance of water and electrolytes, fluid may be retained which can then cause sudden weight gain. This is usually temporary but can be a problem for people with underlying kidney diseases.
  • Maintain regular bowel movements, preferably once or twice daily. Simple measures can help regulate bowel habit. This includes drinking plenty of water, eating high fiber foods, avoiding large amounts of diuretics like alcohol and caffeine and keeping physically active.
  • Use laxatives for constipation if and when prescribed by a health care professional. Always opt for dietary and lifestyle changes but laxatives may sometimes be needed for short periods to counteract the constipation.
  • Always inform a doctor when fluid retention occurs after starting new medication. This can be a side effect of the drug. Never stop the drug to prevent the fluid accumulation unless a doctor advises so.
  • Do not ignore symptoms of fluid retention. Consult with a doctor immediately and follow the prescribed treatment to minimize or prevent fluid retention that can occur with certain diseases.

Please note that any information or feedback on this website is not intended to replace a consultation with a health care professional and will not constitute a medical diagnosis. By using this website and the comment service you agree to abide by the comment terms and conditions as outlined on this page