AIIMS, Stanford-trained doctor explains why some gain weight eating little while others stay lean despite eating more

Dr Sethi highlights that metabolism, not willpower, dictates weight gain, stating that a slower BMR and lower muscle mass result in fewer calories burned.

Have you ever wondered why some people eat small meals to control their weight, still gain it, while others eat without any portion control and manage to stay lean? Dr Saurabh Sethi revealed the reason behind this phenomenon in a recent Instagram post.

According to the gastroenterologist, individuals with fewer muscles tend to burn fewer calories as compared to those who have more. (Freepik)

On December 9, Dr Sethi, a gastroenterologist and hepatologist trained at AIIMS, Stanford, and Harvard Universities, highlighted that it is your metabolism that determines how much weight you gain after eating meals, not your willpower to consume more or less food. Here's how:

Why do some people lose weight even after eating less?

According to the gastroenterologist, everyone's engine is different. He explained, “Basal Metabolic Rate (BMR) is the energy your body burns just staying alive, breathing, thinking, digesting, and pumping blood. Some people are born with a faster BMR - due to genetics, thyroid function, hormones, or higher muscle mass.”

So, how do people fail to stay lean even when they control what they eat? Dr Sethi highlighted that it is because they have a slower BMR, so they burn fewer calories even at rest.

Less muscle = fewer calories burned

Moreover, the gastroenterologist noted that individuals with fewer muscles tend to burn fewer calories at baseline. “This happens after crash diets, long calorie restriction, or muscle loss with age,” he added.

Whereas muscles burn 3 to 5 times more calories than fat, even while resting, he noted. Therefore, more ‘muscle equals higher burning of calories 24x7.’

Explaining how people benefit from having more muscles (from regular activity or exercise), Dr Sethi shared that they can eat more without gaining weight.

“Hormonal imbalances like insulin resistance make it easier to store fat and harder to burn it. Common in fatty liver, PCOS, prediabetes, and diabetes,” he added.

People who gain weight, ‘eating little’ often have:

• Slowed metabolism
• Low muscle mass
• Hormonal imbalance
• High cortisol / hidden stress
• Poor sleep
• Post-diet metabolic adaptation (It's not laziness - it's physiology.)

Those who ‘eat anything’ but stay lean usually have:

• Higher metabolic rate
• Better insulin sensitivity
• More daily movement
• More muscle mass
• Small daily movement adds up more than people think.

Lastly, Dr Sethi highlighted that the goal isn't to eat less, but to optimise how your body burns through more muscle, stable hormones, better sleep, and consistent movement.

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.

This report is based on user-generated content from social media. HT.com has not independently verified the claims and does not endorse them.