Surprising Causes of Weight Gain and When to Worry

We’ve all been there — stepping on the scale followed by a sinking feeling when the numbers don’t add up. Sometimes, weight gain seems mysterious, even when you’re doing everything right. Dr. Jennifer Gabel, UnityPoint Health, shares some surprising culprits lurking behind those extra pounds.

What is Considered Overweight?

Body Mass Index, or BMI, is a quick way for your doctor to get an idea of your body composition. It’s calculated using your height and weight. A BMI between 25 and 29 is considered overweight. Anything over a BMI of 30 indicates obesity. However, BMI doesn’t always give an accurate picture of your health. “It doesn’t account for things like ethnicity, muscle mass, body fat percentage, visceral fat (the unhealthy fat surrounding your internal organs), age or gender. Ultimately, the breakdown of your body composition tells a much more detailed story about your health,” Dr. Gabel says.

Why am I Gaining Weight?

If you’re prioritizing eating healthy and exercise but still have unexplained weight gain, Dr. Gabel says there are several potential reasons for it, including:

• Fluid retention in the body: If you experience rapid weight gain, this signals underlying conditions that impact the heart, liver, and kidneys, as well as an adrenal problem, polycystic ovarian syndrome (PCOS) and hypothyroidism.
• Poor sleep: Not getting enough quality sleep leads to weight gain. Our body’s hunger hormones get out of whack, leading to increased hunger and cravings for high-calorie foods. Sleep apnea, for example, a sleep disorder characterized by pauses in breathing, causes weight gain.
• Stress: An increase in stress hormones, like cortisol, makes our body want to hang on to weight.
• Hidden calories: Empty calories in drinks can cause the pounds to creep up. If you’re tracking your caloric intake, make sure you’re accounting for what’s in your beverages, like those drive-through coffees every morning.
• Sugar substitutes: Artificial sweeteners, such as aspartame or sucralose, trick your brain into thinking it’s getting sugar even though it’s not. This confuses your brain’s neurotransmitters and can lead to changes in mood, energy and increased cravings for sweets.
• Moving to the U.S.: Adapting to an American diet can also lead to weight gain. This is because of our larger portion sizes, readily available processed foods and more sedentary lifestyle.

Why am I Not Losing Weight?

When you've hit a plateau in your weight loss journey, there are a few things to consider:

• Your body’s reached its setpoint: Our bodies naturally gravitate towards a certain weight, referred to as our "setpoint." This is the weight where hormones and neurotransmitters in the gut and brain are most comfortable. Sometimes, your setpoint falls within the overweight range, and you have to work against your body’s natural tendencies to lose weight.
• Your quality of sleep is poor: A common factor in weight gain and stalled weight loss is how well you’re sleeping. Dr. Gabel says, “If you don't get quality sleep, stress hormones trigger our bodies to hang on to energy, and fat cells are a form of energy for our body."
• You’re too focused on exercise instead of nutrition: “You must look at what you’re putting in your body. You can’t out-exercise a poor diet,” Dr. Gabel says.
• You aren't giving your gut a break: Giving your gut time to recover helps improve its function and supports weight-loss efforts. Specifically, rethink any snacking in the evening. “Allow your gut to relax during those overnight hours between dinner and when it's time for breakfast the next day," she says.

Why You’re Losing Inches but Not Weight

When your clothes fit better but the scale isn’t moving, you’re likely losing inches but not weight. While frustrating, don’t stress too much. It’s a sign you’re on the right track.

What’s happening to your physique is called “body recomposition," which means you're losing fat and gaining muscle. Since muscle weighs more than fat and takes up less space, you'll see a slimmer figure when you look in the mirror. However, dropping actual pounds takes some time.

Dr. Gabel says, “The frustrating thing about gaining muscle mass, which is accomplished with eating enough protein and strength training, is you won’t see an increase in your metabolism and breakdown of fat cells for about six months to a year. So, it takes time to see that number go down on the scale, but it will eventually if you stick with it.”

Subcutaneous Fat versus Visceral Fat

Not all fat is created equal — location matters. Visceral fat surrounds our internal organs, like the stomach and liver, on the inside of our abdomen. Subcutaneous fat sits underneath the skin. You can pinch it.

“Visceral fat commonly goes up during menopause and is much more metabolically unhealthy than subcutaneous fat. It also increases your risk of heart disease and type 2 diabetes,” Dr. Gabel says.

To combat age-related muscle loss, especially during menopause, strength training is crucial. It helps maintain muscle mass and a healthy metabolism.

Surprising Causes of Gaining Weight: Prescription Medications

Many medications, while effective in treating various health conditions, have unintended side effects like weight gain. It's a common issue, and understanding which medications contribute to weight gain can help you make informed decisions around nutrition and exercise to offset the impact.

Do Antidepressants Cause Weight Gain?

While it’s not a significant amount, some antidepressants cause weight gain and others actually help with weight loss.

• Gabapentin: Traditionally used to treat conditions like epilepsy, nerve pain and restless legs syndrome, Gabapentin is prescribed for anxiety or mood disorders, too. Some people gain weight on the medication. This is primarily due to Gabapentin’s ability to stimulate the appetite, cause fluid retention and fatigue.
• Lexapro: On average, Lexapro causes minimal weight gain — about 3.5 to 5 pounds after taking the medication for two consecutive years. Starting, stopping and restarting Lexapro many times over increases the risk of weight gain.
• Prozac: Prozac doesn't cause weight gain for most people. It tends to be a pretty weight-neutral antidepressant with no significant weight gain or loss as a side effect.
• Trazadone: Used to treat depression and insomnia, Trazadone is unlikely to cause weight gain. Weight loss is more common.
• Wellbutrin: Wellbutrin doesn’t cause weight gain. In fact, it aids in weight loss, although it’s minimal.
• Zoloft: Weight gain isn’t a notable side effect of Zoloft.

If you feel anxious or depressed, and your doctor prescribes an antidepressant, don't worry about potential weight gain. Focusing on your mental health is more important. Once your mood is stable, you're better equipped to tackle any physical health goals, including weight loss. Remember, things like stress and poor sleep can affect your weight more than medication.

Dr. Gabel says, “Because some antidepressants make you hungrier, be mindful of the food you’re putting in your body. Focus on getting enough protein each day, which helps you feel fuller longer."

Does Birth Control Make You Gain Weight?

A common concern for women when starting birth control is potential weight gain. Dr. Gabel says this is because, historically, birth control pills contained much higher doses of estrogen and progesterone, which caused weight gain. That changed decades ago, when the medical community realized birth control at much lower doses is still effective at preventing pregnancy.

The best birth control options to avoid weight gain are intrauterine devices (IUDs) and low-dose combination birth control pills.

“Where we do see weight gain that’s quite significant is with the Depo-Provera shot and Nexplanon, a little device inserted in the arm,” Dr. Gabel says

Does Estrogen Cause Weight Gain?

Estrogen itself isn’t a direct cause of weight gain.

“Everybody responds differently to these medications. The studies tell us, on average, what’s typical. Stay in tune with your body, and talk to your provider if you’re concerned,” Dr. Gabel says.

Hormonal Weight Gain

Fluctuating hormones can be a factor in weight changes, especially for women during perimenopause and menopause.

Dr. Gabel says, “Our metabolism slows down as we age. It’s especially noticeable during menopause when muscle mass begins to decrease and fat mass increases. You need to be mindful of the quality of food you’re eating, including adequate protein intake and be sure to participate in strength training 2-3 times per week to maintain your weight.”

In women, certain underlying conditions affecting the pelvic organs sometimes lead to weight gain, too. For example, PCOS can cause weight gain, but it's not guaranteed. Additionally, endometriosis causes bloating and discomfort, but it’s not typically associated with significant weight gain. Fibroids, unless they're extremely large, usually don't contribute to weight gain either.

Does Testosterone Make You Gain Weight?

Testosterone can help men maintain muscle mass and burn more calories.

“If your muscle mass improves, you could gain weight in a healthy way," Dr. Gabel says.

There are no adequate, large studies that show testosterone supplementation is safe in women for maintaining muscle mass.

Does Insulin Make You Gain Weight?

“Insulin is a medication commonly used to treat type 2 diabetes, especially if blood sugars are extremely high. It’s necessary to treat type 1 diabetes, because the pancreas can’t produce insulin itself. With type 2 diabetes, insulin may be required short term to quickly bring blood sugars down to a healthy range before other diabetes medications are started. While insulin can lead to weight gain, many other medications to treat diabetes aid weight loss,” Dr. Gabel says.

Insulin resistance is a medical condition commonly associated with PCOS. It occurs when the cells in our body don’t react appropriately and cause glucose to build up in our blood stream. This can lead to weight gain and other health problems, like type 2 diabetes.

“However, with a balanced diet, regular exercise and sometimes medications like metformin or GLP-1 agonists, many women with PCOS can manage their weight, reverse their insulin resistance and improve their overall health.”

Does Levothyroxine Cause Weight Gain?

Prescribed to treat hypothyroidism, levothyroxine doesn’t cause weight gain. While starting it can stop the progression of weight gain, it won’t lead to weight loss.

Which Heart Medications Cause Weight Gain?

Heart medications can significantly improve cardiovascular health, but they sometimes lead to weight gain as a side effect.

• Spironolactone: Used to treat high blood pressure, heart failure and hormonal disorders, Spironolactone doesn’t cause weight gain. It helps regulate fluid balance in the body and decreases water weight. There’s no effect on increasing fat mass.
• Beta Blockers: Dr. Gabel says some older versions of beta blockers are linked to weight gain, but it's minimal. “It tends to happen within the first year, but as long as you stay on it, you won’t continue to gain weight,” she says. Newer beta blockers don’t have weight gain as a side effect.
• Statins: Statins, effective in lowering cholesterol levels, don’t have weight gain as a side effect.

Does Accutane Cause Weight Gain?

A commonly prescribed medication for treating stubborn acne, there aren't significant studies pointing to weight gain as a side effect. Sometimes, people experience a decrease in appetite.

Surprising Causes of Gaining Weight: Supplements

While supplements can offer a helpful boost, they're not a magical solution for weight loss.

• Creatine: While you may experience some initial water weight, creatine doesn’t make you gain weight and won’t cause an increase in fat. It's designed to support muscle mass, which leads to fat loss over time.
• Protein shakes: If it's low in carbohydrates and sugar, protein shakes don’t make you gain weight. Along with strength training, they support muscle mass.
• St. John’s Wart: There's no evidence St. John’s Wart causes weight gain. However, keep in mind supplements have side effects that may impact your weight in other ways, like affecting your sleep or mood.

Does Inflammation Cause Weight Gain?

Yes, inflammation leads to weight gain. Dr. Gabel says, “Inflammation and weight gain tend to feed off each other. Inflammation causes an increase in fat deposits, and fat cells cause more inflammation.”

If not addressed, this can lead to an endless cycle in the body.

Used to treat inflammation, steroids cause weight gain when used long-term. Prednisone, a type of steroid, may cause initial water weight when used in short bursts but won’t increase fat mass.

What Foods Make You Gain Weight the Fastest?

A diet high in simple carbohydrates, like what's found in processed foods and sugary drinks, fried food, alcohol and high fructose, significantly impacts weight gain. Additionally, artificial sweeteners, like aspartame, can make you gain weight by altering your brain chemistry and increasing cravings for sugary foods.

Does Diet Soda Make You Gain Weight?

Dr. Gabel has some bad news for diet soda lovers. “Most research shows diet soda can make you gain weight. In fact, people who drink diet soda versus regular soda consume more calories in a day and weigh more. This is because of how the artificial sweeteners, like aspartame, affect your brain and food cravings.”

Does Coffee Make You Gain Weight?

By itself, coffee won’t make you gain weight. In fact, Dr. Gabel says coffee has a ton of health benefits and can slightly increase your metabolism. “You just have to be careful of the amount of sugar and sweeteners you add to it. That’s where hidden calories creep in.”

Does Oatmeal Make You Gain Weight?

Oatmeal contains fiber and vitamins that are good for you. Eating it in moderation, and not adding too many sugary toppings, is good for weight loss.

Does Rice Make You Gain Weight?

White rice is a simple carbohydrate. If you eat a lot of white rice, it can increase the number of fat cells in your body and lead to weight gain.

Why Am I Gaining Weight After Working Out?

One potential reason for feeling heavier after a workout is increased water weight. When you exercise, your body loses fluids through sweat. As you rehydrate, you may retain water, leading to a temporary increase in weight. Additionally, as you gain muscle mass through strength training, you might see an increase on the scale, even if your body fat decreases. It's important to focus on body composition changes, rather than just weight, to get a full picture of your progress.

When to See a Doctor About Weight Gain

While it’s normal for weight to fluctuate throughout the day, sudden weight gain is alarming. Putting on five pounds in a week, or two to three pounds in 24 hours, is a good reason to talk to your doctor if nothing’s changed in your day-to-day.

“If you can’t get to the bottom of unexplained weight gain, talk to your doctor to make sure there’s nothing serious going on,” Dr. Gabel says.

Don’t sweat the daily ups and downs with your weight. When you eat, how much water you drink and even your bathroom habits can impact the numbers on the scale. If you’re feeling frustrated with your progress, schedule an appointment with your primary care provider to create a plan for success.