Stay in shape to ensure you can keep major health risks at bay. Find out how extra weight harms your organs. 

BMI, or Body Mass Index, is one of the most common ways to check if a person’s weight is healthy. The BMI scale classifies people as underweight, healthy, overweight, or obese. Many people ignore a little extra weight, especially after the festive season when rich food leads to slight weight gain. But dismissing even small weight increases can have serious effects. Those few extra kilos can strain the heart and other vital organs.

Health risks of extra weight

To explain how even mild weight gain affects health, Dr V Mohan, Chairman of Dr Mohan’s Diabetes Specialities Centre and President of the Madras Diabetes Research Foundation, spoke to HT Lifestyle. He said that extra weight raises the risk of type 2 diabetes, heart disease, and fatty liver.

Citing the 2025 World Heart Report, Dr Mohan noted that one in ten deaths from heart disease is linked to a high BMI or large waistline. This shows why ignoring weight gain can be dangerous and even life-threatening.

How obesity harms the heart

Dr Mohan explained, “Obesity puts extra strain on the heart and blood vessels, increasing the risk of heart disease. When fat builds up around the belly, it can raise blood pressure and cholesterol levels.”

Impact on gut, liver, and kidneys

The effects of excess weight are not limited to the heart. It also harms other organs, including the gut, liver, and kidneys. Dr Mohan explained that fat around internal organs, called visceral fat, is particularly harmful.

“In the liver, this fat can cause swelling and scarring. Kidneys have to work harder to filter blood, which can cause long-term damage. The gut is also affected, as extra weight disrupts the balance of good bacteria, leading to inflammation and poor digestion,” he said.

Metabolic effects

Extra weight also disrupts the body’s metabolism. “Weight gain doesn’t just add bulk,” Dr Mohan said. “It triggers changes like insulin resistance, which can lead to type 2 diabetes. Blood pressure rises, cholesterol levels fluctuate, and chronic inflammation sets in.”

Beyond BMI

While BMI is a common tool, Dr Mohan said it does not tell the full story. Waist size or waist-to-height ratio are better indicators of abdominal fat, which is closely linked to metabolic diseases. Advanced tests like body composition scans (DEXA, MRI) can give even more detailed information.

In short, BMI is only part of the picture. Combining it with other measurements gives a clearer view of overall health risks.