Why Am I Gaining Weight: 7 Underlying Causes

If you find yourself asking “why am I gaining weight when I’m not doing anything different,” you may have unintentional weight gain. Keep reading to learn all about it and the possible causes.

RELATED: How To Maintain Weight Loss In A Healthy Way

7 Reasons for Unintentional Weight Gain: Why Am I Gaining Weight?

1. Aging

As you age, your metabolism naturally slows down. In fact, your body’s resting metabolic rate declines as you age.

What is a resting metabolic rate? This is the rate at which your body burns calories while it’s at an inactive or resting state.

Lower resting metabolic rates are mostly due to a decrease in fat-free mass and muscle mass—both of which also tend to decrease as you age. This loss of fat-free mass and muscle mass is usually seen in the abdominal area.

It’s important to remember aging doesn’t usually cause sudden weight gain. It usually happens over time, so rapid weight gain may be caused by other medical or lifestyle issues.

2. Poor Sleep Quality

When you don’t get enough sleep at night, you can also cause some unwanted weight gain. It usually boils down to two factors:

  • Late-night snacking
  • Hormonal changes

When you’re burning the midnight oil, you’re more likely to snack on junk food to help keep you up. But even if you aren’t snacking, skimping on sleep can cause hormonal changes in the long run.

When you’re sleep-deprived, there’s a decrease in leptin and an increase in ghrelin. Leptin is the hormone responsible for regulating satiety or feeling full.

On the other hand, ghrelin is the hormone responsible for regulating hunger. So when you don’t get enough sleep, you need to eat more to feel full and you get hungry more often—both of which can lead to weight gain.

3. Chronic Stress

Your body releases cortisol to respond to stress. Cortisol is a stress hormone which activates the fight or flight response and it can also increase your appetite.

However, short-term or acute stress doesn’t usually cause weight gain. In fact, it causes your body to mobilize your energy stores to respond to the stressful event.

Chronic stress is a different story. When you’re always stressed, your body goes into survival mode.

It can promote the constant acquisition of energy stores—or, in other words, chronic stress can encourage overeating. Worse, stress can also negatively impact your regular diet because it increases your cravings for “comfort foods” which are usually high in fat and sugar.

4. Going Cold Turkey on Smoking

Smoking is addictive and it can increase your risk for a variety of cardiovascular and lung issues. So it’s always a good idea to stop smoking.

Unfortunately, one of the unwanted effects of giving up smoking is weight gain. Different studies report different rates of weight gain for successful quitters.

On average, people who successfully give up smoking can gain 2-5 kgs each year compared to those who continue smoking.

When you quit smoking, you’re also quitting nicotine. Nicotine can increase satiety and decrease your appetite.

So when you quit, you may feel hungry more often. On top of that, some people need to substitute the “hand to mouth” habit with something else—usually eating.

These effects are usually felt the most during the first few weeks after quitting. Over time, your appetite should begin to stabilize and you can work on losing the weight you put on.

RELATED: What Are The Symptoms Of Hormonal Imbalance?

5. Hormonal Changes

Hormones tell your body what it’s supposed to do and when it’s supposed to do it. If there are any drastic hormonal changes, it can have an effect on your overall health, daily functioning, and even your body weight.

Here are examples of conditions which can cause hormone-related weight gain:


During menopause, the body produces less estrogen, which can cause weight gain in women, especially in the hips and abdominal region.

Polycystic Ovary Syndrome (PCOS)

PCOS is a condition wherein women have higher levels of male hormones and develop insulin resistance. When your body is more resistant to insulin, it’s less effective in converting sugar or glucose into energy.

Over time, glucose and insulin can build up in the bloodstream. The body responds to this by producing more androgen, a male hormone which causes body hair growth, irregular periods, and weight gain.


Hypothyroidism is a condition wherein the thyroid gland isn’t producing enough thyroid hormones. If you don’t have enough thyroid hormones, your metabolism becomes slower which may lead to more weight gain.

Cushing’s Syndrome

Cushing’s syndrome is a condition wherein the body produces too much cortisol for an extended period of time. This chronic exposure leads to weight gain in the abdomen, face, neck, and upper back.

6. Medications

Weight gain may also be the result of certain medical treatments and medications.

Here are a few conditions which are treated with drugs that may cause weight gain:

  • Depression
  • Schizophrenia
  • Bipolar disorder
  • Migraines
  • Seizures
  • High blood pressure
  • Diabetes
  • Rheumatoid arthritis
  • Asthma
  • Systemic lupus erythematosus

Antidepressants, antipsychotics, and steroidal drugs can cause weight gain. Women taking hormonal birth control pills can sometimes feel like they’re gaining weight as well, but this is most likely due to short-term fluid retention.

7. Kidney Disease

Weight gain and swelling are symptoms of kidney damage. The kidney’s main job is to help your body filter waste by transforming it into urine.

If your kidneys aren’t working properly, the body may retain waste and fluid in the tissue. This can lead to weight gain and swelling in the legs, feet, and ankles.

Weight gain can be explained by a change in eating habits, calorie intake, general physical activity, or exercise routines. If you haven’t been making any drastic changes in these areas, something else may be causing it.

It’s best to talk to a healthcare professional to uncover the underlying causes. Contact LIV Health today and they can connect you with an integrative health specialist who can help you with your weight-loss goals and other health concerns.

What are the steps you’ve taken to manage unintentional weight gain? Share them with us in the comments section below.

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