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9 Underlying Causes of Weight Gain

a healthy meal weight gain

If you're having difficulty losing weight and you've tried everything, you're not alone and it's not all in your head. There can be many underlying causes of weight gain so it's important to get them checked out because addressing these causes may help you lose the weight more easily.

In this post I go over nine possible reasons for weight gain and how you can get them checked out.

Underlying Causes of Weight Gain

Hypothyroidism - The thyroid gland controls a lot of functions including your metabolism. Low thyroid function can slow down your metabolism making weight loss difficult. Your thyroid can be checked by doing a thyroid panel for TSH, free T3, and free T4. Checking for thyroid antibodies may also be helpful to see if the hypothyroidism is caused by an autoimmune disease called Hashimoto's.

Epstein Barr Virus (EBV) - This viral infection is also known as mononucleosis and can become reactivated if you experience trauma, stress or illness. A chronic viral infection like reactivated EBV puts stress on the body and causes systemic inflammation, both of which can lead to weight gain. It also makes you feel tired, can contribute to hypothyroidism and lead to depression. EBV can be checked by doing a blood test to look for specific antibodies for the virus. The stool test I do, GI-MAP by Diagnostic Solutions, also checks for this virus on their panel.

Insulin resistance or diabetes - Insulin is released when you eat so that cells know to take in the glucose in the blood. If your cells aren't responsive to insulin, the glucose stays in your bloodstream and can be stored as fat. Women in menopause can gain weight due to changes in their body's response to insulin. Blood sugar can be checked with a blood test looking at fasting insulin, fasting glucose, and hemoglobin A1c, which gives a picture of how you're blood sugar has been over the last 3 months.

Depression or anxiety - Both of these conditions can lead to poor sleep, increased appetite and reduced activity. If you're not sleeping well, not staying active and are eating to make yourself feel better, weight can increase easily. Your health care provider can ask you about certain symptoms to determine if you may be experiencing either depression or anxiety.

Heart, liver or kidney disease - Dysfunction in any of these organs can lead to poor circulation, low protein production and changes in electrolyte levels, which can lead to water retention. These can be checked with blood tests as well as imaging.

Not eating enough - If you're a long time dieter you've probably become accustomed to thinking that eating less means more weight loss. Yes, eating less calories can lead to weight loss, but if you eat too few, your body will hold onto the weight because it thinks you're in starvation mode. Track how many calories you're eating per day using apps like Lose It, My Fitness Pal or Carb Manager. Do this for 1-2 weeks without trying to change your eating habits. In general, you want to be eating at least 1200 calories per day and staying between 1200 - 1500 calories per day can result in weight loss, but this number can vary depending on your activity level.

Digestive issues - Having chronic gut infections or inflammation from food sensitivities can lead to weight gain because these put your body into a chronically stressed state. You're also not digesting well and may become malnourished. Reflux or GERD symptoms at night can interfere with sleep, leading to weight gain. Gut health can be determined by your symptoms, stool tests or imaging studies.

Chronic stress - When you're under long term stress, the adrenal glands pump out stress hormones like cortisol to keep you in that "fight or flight" state. This can be helpful short term, but detrimental to many aspects of your health if it becomes chronic. Stress continues the cycle by interfering with your sleep, appetite, and mood which can be contributing factors to weight gain. Adrenal function can be checked with blood tests like AM cortisol or saliva/urine tests that have you take samples throughout the day. I like to use the DUTCH test for this.

Poor sleep - Many important things happen when we sleep deeply. Our bodies repair muscle and tissue, produce hormones that regulate growth and appetite and take the information we encountered during the day and make long term memories. Deep, restful sleep is vital for our mood, immune system, weight management, blood sugar and heart health. If you snore, you may want to get checked out for a condition called sleep apnea that can be checked out with an overnight sleep study.


Weight gain can be caused by many underlying conditions that are worth looking into. This post goes over many causes and how you get them checked out by your healthcare provider. Nine causes of weight gain include hypothyroidism, EBV, diabetes, depression, anxiety, heart, liver or kidney disease, not eating enough, digestive issues, chronic stress, and poor sleep.

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In health,

Dr. Jamie

This website is not intended for the purpose of providing medical advice. All information, content, and material of this website is for informational purposes only and are not intended to serve as a substitute for the consultation, diagnosis, and/or medical treatment of a qualified physician or healthcare provider.


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