What causes weight gain?
LAST UPDATED: Jun 27, 2022
4 MIN READ
HERE'S WHAT WE'LL COVER
Discovering your favorite pair of jeans are a little too snug, or the zipper on that dress you planned to wear tonight doesn’t want to budge can be disheartening, especially when you are in the dark as to why this is happening. So what causes weight gain? You might be surprised to learn it comes down to more than just diet and exercise.
As we get older, the number on the scale can fluctuate with significant life events, health status, and lifestyle changes. So, pinpointing the cause of unexplained weight gain can be tricky. This article dives into the various causes of weight gain and steps you can take to reverse weight gain if that’s your goal.
Fad diets stop here
If appropriate, get effective weight loss treatment prescribed for your body.
5 common causes of weight gain
Body weight is affected by much more than the calories we consume. Medications, sleep, hormone changes, and certain medical conditions can affect how the body stores fat.
Keep reading to understand the most common causes of weight gain and when you should seek medical advice.
1. Medical conditions
Obesity and unexpected weight gain may be triggered by underlying medical conditions that alter metabolism and cause a chemical imbalance, leading to fluctuations in weight.
Hyperthyroidism is caused by an underactive thyroid leading to a slower metabolism.
Cushing’s syndrome is caused by the overproduction of the stress hormone cortisol leading to excess weight in the face, neck, trunk, and abdomen.
Polycystic ovary syndrome (PCOS) is an imbalance of reproductive hormones that creates problems in the ovaries, often resulting in unexpected weight gain.
Heart disease and heart failure can cause excess fluid stored in your body called edema resulting in swollen ankles, feet, legs, and abdomen.
Kidney disease can cause fluid retention, leading to high blood pressure, excess water weight, and bloating.
Menopause isn’t directly responsible for weight gain. Still, it is associated with decreased estrogen levels and changes in fat distribution, specifically in the abdomen, which can lead to weight gain.
Type 2 diabetes and some medications used to treat it are associated with weight gain.
A routine blood test can help healthcare professionals rule out these conditions as possible causes of unexpected weight gain.
2. Eating habits
The foods we consume keep our bodies working and provide us with energy. Eating more calories than you need, though, can contribute to weight gain. And too much of certain types of food can make this more likely.
One study found the following food categories led to long-term excess weight gain in adolescents (Dong, 2015):
Fat spreads (butter or margarine)
Coated poultry (breaded or battered)
Potatoes cooked in oil (french fries, potato chips)
Desserts and sweets
Sugar-sweetened beverages (soda, fruit drinks)
Another study found that ultra-processed foods make up 51% of total caloric intake, increasing levels of sodium, cholesterol, and fats resulting in long-term weight gain and higher body fat (Bielemann, 2015).
That doesn’t mean you can never eat these foods—no food is inherently bad. But primarily eating a diet rich in whole grains, vegetables, and fiber while minimizing snacking can reduce fluid retention and constipation and help promote a healthy weight.
3. Lack of physical activity
Daily life offers many opportunities for inactivity. Working at a desk, watching TV, and commuting long distances contribute to an increasingly sedentary lifestyle, which studies show causes chronic health conditions and weight gain (Ladabaum, 2014).
Controlling blood sugar and lowering the risk of type 2 diabetes
Reducing blood pressure
Preventing cardiovascular disease
Reducing stress, anxiety, and depression
Promoting weight loss
Helping to maintain a healthy body mass index (BMI)
If you have sudden or unexpected weight gain, it might be from a medication you take. Many drugs can cause weight gain when taken over a long period.
Studies have shown that the following classes of medications can contribute to weight gain (Domecq, 2015):
Drugs used to treat type 2 diabetes
Speak to your healthcare provider if you are concerned that your medication is causing sudden weight gain. There may be an alternative treatment plan available.
5. Sleep disturbances
Quality sleep is vital to mental and physical health. Studies show that one in three people don’t get enough sleep, leading to a rise in various health conditions, including weight gain and obesity (CDC, 2017).
One study found that people who had less than seven hours of sleep were more likely to have a higher BMI than those who got more sleep on average. People who got less sleep also had specific biomarkers associated with obesity, including salt retention, inflammatory markers, and decreased levels of leptin, a hormone that helps regulate appetite (Cooper, 2018).
Moderate to severe sleep apnea is also associated with sleep deprivation and weight gain. Sleep apnea can result in daytime sleepiness, leading to a lack of energy, less physical exercise, and poor diet choices (Nedeltcheva, 2010; Jehan, 2017).
What to do if you have sudden weight gain
Sometimes, we gain weight despite eating a healthy diet and exercising regularly. While it’s normal for weight to fluctuate over time, there are circumstances when you should seek help from a healthcare provider. Talk to a professional if you are experiencing any of the following in combination with sudden weight gain (Wilson, 2021; AHA, 2017):
Sudden excessive weight gain without a known cause
Uncontrolled hunger with sweating and heart palpitations
Feel colder than usual
Shortness of breath
Proven ways to lose weight
Losing weight is not easy, and different strategies work for other people. Eating right and increasing physical activity are proven strategies for weight loss.
A 2018 study found that dietary changes in people who successfully lost weight had three things in common: eating more vegetables, consuming less sugar, and eating more whole foods instead of processed foods (Gardner, 2018).
In addition to improving your eating habits and moving your body, other strategies to help you lose weight include (CDC, 2022):
Getting plenty of sleep
Drinking lots of water
Eating high-fiber foods
Tracking your eating
Setting realistic goals
Identifying resources for support and information
Making changes to your environment to limit overeating
Unexplained weight gain can be frustrating and stressful. It can be caused by several factors beyond diet and exercise, including certain medical conditions, medications, sleep quality, and stress.
See a healthcare provider If you experience sudden weight gain in conjunction with other health changes such as swollen feet, hair loss, vision changes, and uncontrolled hunger.
If you have any medical questions or concerns, please talk to your healthcare provider. The articles on Health Guide are underpinned by peer-reviewed research and information drawn from medical societies and governmental agencies. However, they are not a substitute for professional medical advice, diagnosis, or treatment.
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