If you can smell something does that mean that this thing loses molecules? When you can smell something there must be some molecules in your nose which signalize the smell in your nose. Does that mean, that e.g. a cheese is losing molecules which fly into your nose?
And does that effect the weight or amount significantly?
Yes, the thing you smell surely does lose some molecules, and consequently some weight. It can be said that it slowly evaporates or sublimates. But the strength of smell varies greatly in different compounds, as does the rate of evaporation (sublimation). Some compounds may be gone completely in a few minutes, and some would stay for years, or even decades.