Der Gewichtsverlust zeigt den Röstgrad.

Because the two nouns are in different cases.

• der Gewichtsverlust is the subject of the sentence, so it is in the nominative case.
• den Röstgrad is the direct object of zeigt, so it is in the accusative case.

Both Gewichtsverlust and Röstgrad are masculine nouns, so their articles change like this:

• nominative masculine: der
• accusative masculine: den

That is why the sentence has der ... zeigt den ...

Yes. In German, it is very common to form compound nouns by writing several ideas as one word.

Gewichtsverlust = Gewicht + -s- + Verlust

• Gewicht = weight
• Verlust = loss
• the -s- is a linking element often used in compounds

So Gewichtsverlust literally means weight loss.

This is a very typical German pattern:

• Arbeitszeit = work time
• Lebensmittel = foodstuffs / groceries
• Jahresende = end of the year

The verb zeigen often means to show, to indicate, or to reveal, and it commonly takes a direct object in the accusative.

In this sentence:

• Der Gewichtsverlust = what does the showing/indicating
• zeigt
• den Röstgrad = what is shown/indicated

So the structure is:

subject + verb + accusative object

Examples:

• Die Anzeige zeigt die Temperatur. = The display shows the temperature.
• Das Ergebnis zeigt den Unterschied. = The result shows the difference.

Röstgrad is another compound noun:

• rösten = to roast
• der Grad = degree / level

So Röstgrad means degree of roasting or roast level.

This kind of word is common in coffee, cocoa, malt, and food-processing contexts. Depending on context, English translations could include:

• roast level
• degree of roast
• roasting level

Because all nouns are capitalized in German.

So in this sentence:

• Gewichtsverlust is capitalized because it is a noun
• Röstgrad is capitalized because it is a noun

This is one of the most noticeable differences from English.

The ö sound does not exist in the same way in standard English, so it can feel unfamiliar.

A rough guide:

• ö is a front rounded vowel
• It is somewhat similar to the vowel in French peu or deux
• For English speakers, one trick is: say eh or ay with your tongue forward, but round your lips

Very roughly:

• Röstgrad sounds something like RERST-graht or RURST-graht, but those are only approximations

Also:

• ö is not the same as o
• Rostgrad and Röstgrad would sound different

Because standard German main clauses usually follow the V2 rule: the finite verb comes in the second position.

Here the sentence is:

Der Gewichtsverlust | zeigt | den Röstgrad.

• Position 1: Der Gewichtsverlust
• Position 2: zeigt
• Then the rest: den Röstgrad

This is the normal word order for a simple statement.

You could also move another element to the front, but the verb still stays second:

• Den Röstgrad zeigt der Gewichtsverlust.

That version is grammatically possible, but much less neutral.

Often yes, but not always exactly. zeigen can mean:

• to show
• to indicate
• to demonstrate
• to reveal

In this sentence, indicates or shows both work well in English.

So zeigt here is not necessarily about physically displaying something on a screen. It can mean that the weight loss is an indicator of the roast level.

Yes, that is possible, but it means something slightly different in tone.

• zeigt den Röstgrad = directly shows / indicates the roast level
• weist auf den Röstgrad hin = points to the roast level / indicates it more indirectly

So zeigen sounds more direct and straightforward. hinweisen auf sounds a bit more like to point toward or to be an indication of.

In this sentence, the articles mainly show the case:

• der = nominative masculine
• den = accusative masculine

The nouns themselves, Gewichtsverlust and Röstgrad, do not need extra endings here.

This is very normal in German. Often the article carries the clearest case information, especially with masculine singular nouns.

It can be used in many contexts. It is not only medical.

For example:

• in medicine: ungewollter Gewichtsverlust = unintended weight loss
• in manufacturing or food processing: loss of mass during drying, roasting, or heating
• in everyday life: body weight loss

So in this sentence, Gewichtsverlust most likely refers to a technical or measurable reduction in weight, not necessarily a person losing body weight.