Why Some People Eat Less but Don't Lose Weight

You've probably met someone like this. Eats one meal a day. Barely any carbs. Steps on the scale every morning. And the number doesn't budge.

We asked Dr. Ma Jun, an endocrinologist in Shenzhen, what's going on.

"First thing I check is thyroid," he said. "Low T3, low T4—you can starve yourself and still not lose."

He also looks at insulin. Chronically high insulin tells the body to store, not burn. Even if calories are low.

"Then there's the muscle factor," Ma adds. "More muscle, higher resting burn. If someone's lost muscle over the years, their engine is smaller."

His advice? Get blood work done before you blame yourself. Know your numbers. Then build a plan that fits what's actually happening inside.