You Think You're Losing Fat, But You're Actually Losing Muscle?! Many People Overlook This Problem

A 38-year-old woman lost 10 kg on tirzepatide and strict dieting — but 3 kg of that was muscle. Body composition analysis reveals what the scale cannot: whether you're truly getting healthier or just getting lighter.

Not long ago in clinic, I saw a 38-year-old woman. Over the past few months, she had lost about 10 kg through injections of tirzepatide — a weight-loss medication that has become globally popular in recent years — combined with fairly strict dieting. But she was puzzled: she had gotten thinner, yet her overall condition hadn't noticeably improved. She felt more fatigued than before, her energy had declined, and even climbing just two flights of stairs left her breathless.

Looking at this woman whose BMI (Body Mass Index, used to assess whether weight falls within a normal range) had already fully reached the healthy target, I paused and arranged a body composition analysis for her (our center uses DEXA scanning).

The results were not encouraging. The report showed that despite a normal BMI, her body fat percentage was as high as 36%, placing her around the 90th percentile among women her age. At the same time, her muscle mass was significantly low — her ASMI (Appendicular Skeletal Muscle Index, reflecting limb muscle content) was only about 5.5, falling near the bottom 10% of her peers.

In other words, over the past few months she had indeed lost weight, but not in the right way. Of the weight she lost, in addition to fat, a substantial portion came from muscle. She had put in tremendous effort, yet she wasn't just 'losing fat' — she was also losing muscle.

And this is far from an isolated case. In the pursuit of weight loss, far too many people fall into the same trap — treating the number on the bathroom scale as the whole truth about their health.

The Right Weight Equals Health? That's the Biggest Misconception

In most people's minds, weight loss is a 'numbers game': if the number on the scale goes down, it's a victory; if it goes up, it's a failure. But the rules of this game have been wrong from the very start.

Modern medical research tells us clearly: body weight as a metric is neither precise nor scientific.