Weight gain is usually associated with a sedentary lifestyle, frequent consumption of junk food, or insufficient physical activity. However, when the numbers on the scale continue to rise despite mindful eating habits and regular movements, then the cause may be deeper, beyond behavioural or lifestyle factors.
To understand one of these unseen causes, HT Lifestyle connected with Dr Gaurav Jain, senior consultant of internal medicine at Dharamshila Narayana Superspeciality Hospital, Delhi. According to him, unexplained weight gain can often be linked to an imbalance in the thyroid gland, which plays a crucial role in regulating the body’s metabolism.
“When the thyroid becomes underactive, a condition known as hypothyroidism, the body’s metabolic processes slow down, leading to gradual and often confusing weight gain,” he explained.
How do you know if your weight gain is connected to a thyroid imbalance? Some subtle signs are often attributed to other causes, as they tend to overlap with common health issues. This is why paying closer attention to these symptoms is crucial so that you can distinguish and identify.
Dr Gaurav Jain shared 5 signs:
1. Weight gain despite normal eating habits
Dr Jain explained that weight gain is the first red flag with an underactive thyroid, particularly when there has been no major change in diet or lifestyle.Why does this happen? He explained, “A sluggish thyroid slows down the body’s calorie-burning rate, leading to fat accumulation, particularly around the abdomen.” Another key indicator that he informed is that weight is very hard to lose, even if you are regularly exercising.
2. Persistent fatigue and low energy levels
Exhaustion is generally linked to stress or burnout. In fact, fatigue overlaps with several mental and physical issues, which is why it is often overlooked. However, Dr Jain pointed out that persistent, unexplained fatigue can also be an early sign of an underactive thyroid, especially when it occurs alongside gradual weight gain and low energy levels.
He described why this happens: “ Thyroid hormones are essential for energy production. When levels drop, the body feels constantly tired and sluggish. This ongoing fatigue reduces physical activity, further contributing to weight gain and a feeling of heaviness in the body.”
3. Dry skin, hair fall and slow nail growth

Changes in the skin, hair, and nails may look like cosmetic issues that require you to change your skincare, haircare or manicure routine, but sometimes they can be associated with deeper health issues. Dr Jain cautioned that an underactive thyroid affects the skin’s ability to retain moisture, making makin it dry, rough, and less elastic.
He named some changes, “Hair fall is common, and hair may become thin or brittle. Nails often grow more slowly and may appear weak or ridged.”
4. Hormonal imbalance and menstrual changes in women
Thyroid health is closely linked to reproductive health, which means it can impact hormone levels and make women more likely to experience problems associated with hormonal disruptions when the thyroid is underactive.
Describing how the menstrual flow gets affected, “In women, hypothyroidism can disrupt menstrual cycles, making them irregular, heavy or painful.”
Dr Jain also elaborated that low thyroid hormone levels can disturb hormonal balance, leading to fluid retention and increased fat storage, which can result in unexplained weight gain.
5. Neck swelling, eye symptoms and digestive slowdown

Physical changes in the neck and eyes, along with digestive issues, can also point to thyroid dysfunction.
Dr Jain shared these 3 signs related to these areas:
- An enlarged thyroid may appear as a swelling in the neck and can sometimes cause difficulty in swallowing.
- Mild vision disturbances, blurred vision and puffy eyes may also be present.
- Digestion slows down, leading to bloating and constipation, which can add to weight gain and discomfort.
In conclusion, the doctor warned about a couple of important points. Firstly, unexplained weight gain and other subtle symptoms should not always be dismissed. Secondly, with the increasing use of non-iodised salts and changing dietary patterns, early and subclinical thyroid disorders are increasingly common.
Note to readers: This article is for informational purposes only and not a substitute for professional medical advice. Always seek the advice of your doctor with any questions about a medical condition.
