- People with slower BMR burn fewer calories at rest due to genetics or hormones
- Muscle mass boosts calorie burn 3–5 times more than fat even during rest
- Insulin resistance and hormonal imbalances contribute to easier fat storage
We all know someone like this. They say they “barely eat” but still gain weight. And then there is that one friend who seems to eat all day and never puts on a kilo. It feels unfair and confusing. But weight gain is not just about willpower. It is not just about eating less. The body is more complex than simple calorie math.
Saurabh Sethi, MD, MPH, a gastroenterologist trained at AIIMS, Harvard, and Stanford University, explains this clearly on Instagram. He speaks about Basal Metabolic Rate, or BMR. That is the energy your body burns just to stay alive.
Why Some People Gain Weight Easily
Some people are born with a slower BMR. This can be due to genetics, thyroid function, hormones, or lower muscle mass. A slower metabolism means fewer calories burned at rest.
The health expert also points out that muscle matters a lot. Muscle burns 3–5 times more calories than fat, even when you are resting. Less muscle means lower calorie burn all day.
This often happens after:
- Crash diets
- Long-term calorie restriction
- Muscle loss with age
Hormonal issues also play a role. Insulin resistance makes it easier to store fat and harder to burn it. This is common in fatty liver, PCOS, prediabetes and diabetes.
People who gain weight “eating little” often have:
- Slowed metabolism
- Low muscle mass
- Hormonal imbalance
- High cortisol or hidden stress
- Poor sleep
- Post-diet metabolic adaptation
“It's not laziness. It's physiology,” Dr Sethi explains.
Why Some People Stay Lean Easily
On the other hand, those who seem to “eat anything” and stay lean usually have:
- Higher metabolic rate
- Better insulin sensitivity
- More muscle mass
- More daily movement
Even small daily movements, like walking, standing and fidgeting, adds up. It all burns energy.
The Real Goal
The answer is not extreme dieting. The goal is to improve how your body burns energy.
That means:
- Building muscle
- Improving sleep
- Managing stress
- Supporting hormone health
- Moving consistently
Weight is not just about how much you eat. It is about how your body uses what you eat.
Disclaimer: This content including advice provides generic information only. It is in no way a substitute for a qualified medical opinion. Always consult a specialist or your own doctor for more information. NDTV does not claim responsibility for this information.
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